Gene Summary

Gene:MUTYH; mutY DNA glycosylase
Aliases: MYH
Summary:This gene encodes a DNA glycosylase involved in oxidative DNA damage repair. The enzyme excises adenine bases from the DNA backbone at sites where adenine is inappropriately paired with guanine, cytosine, or 8-oxo-7,8-dihydroguanine, a major oxidatively damaged DNA lesion. The protein is localized to the nucleus and mitochondria. Mutations in this gene result in heritable predisposition to colon and stomach cancer. Multiple transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Jul 2008]
Databases:OMIM, VEGA, HGNC, Ensembl, GeneCard, Gene
Protein:A/G-specific adenine DNA glycosylase
Source:NCBIAccessed: 06 August, 2015


What does this gene/protein do?
Show (18)

Cancer Overview

Research Indicators

Publications Per Year (1990-2015)
Graph generated 06 August 2015 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • Signal Transducing Adaptor Proteins
  • Penetrance
  • Adenomatous Polyposis Coli Protein
  • Asian Continental Ancestry Group
  • Genetic Predisposition
  • Genetic Testing
  • Phosphoric Monoester Hydrolases
  • Colonoscopy
  • Nuclear Proteins
  • Chromosome 1
  • APC
  • Germ-Line Mutation
  • Childhood Cancer
  • DNA Repair Enzymes
  • DNA Glycosylases
  • Microsatellite Instability
  • Base Sequence
  • DNA Mismatch Repair
  • Breast Cancer
  • Heterozygote
  • Case-Control Studies
  • DNA Mutational Analysis
  • DNA Damage
  • Adenomatous Polyposis Coli
  • DNA-Binding Proteins
  • Cancer Gene Expression Regulation
  • Alleles
  • Adolescents
  • ras Proteins
  • Genetic Variation
  • Genotype
  • DNA Repair
  • Genetic Association Studies
  • Single Nucleotide Polymorphism
  • Cohort Studies
  • Risk Assessment
  • Hereditary Nonpolyposis Colorectal Cancer (HNPCC)
  • Intestinal Polyposis
  • Age of Onset
  • Adenoma
  • Colorectal Cancer
Tag cloud generated 06 August, 2015 using data from PubMed, MeSH and CancerIndex

Specific Cancers (5)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: MUTYH (cancer-related)

Chubb D, Broderick P, Frampton M, et al.
Genetic diagnosis of high-penetrance susceptibility for colorectal cancer (CRC) is achievable for a high proportion of familial CRC by exome sequencing.
J Clin Oncol. 2015; 33(5):426-32 [PubMed] Related Publications
PURPOSE: Knowledge of the contribution of high-penetrance susceptibility to familial colorectal cancer (CRC) is relevant to the counseling, treatment, and surveillance of CRC patients and families.
PATIENTS AND METHODS: To quantify the impact of germline mutation to familial CRC, we sequenced the mismatch repair genes (MMR) APC, MUTYH, and SMAD4/BMPR1A in 626 early-onset familial CRC cases ascertained through a population-based United Kingdom national registry. In addition, we evaluated the contribution of mutations in the exonuclease domain (exodom) of POLE and POLD1 genes that have recently been reported to confer CRC risk.
RESULTS: Overall mutations (pathogenic, likely pathogenic) in MMR genes make the highest contribution to familial CRC (10.9%). Mutations in the other established CRC genes account for 3.3% of cases. POLE/POLD1 exodom mutations were identified in three patients with family histories consistent with dominant transmission of CRC. Collectively, mutations in the known genes account for 14.2% of familial CRC (89 of 626 cases; 95% CI = 11.5, 17.2).
CONCLUSION: A genetic diagnosis is feasible in a high proportion of familial CRC. Mainstreaming such analysis in clinical practice should enable the medical management of patients and their families to be optimized. Findings suggest CRC screening of POLE and POLD1 mutation carriers should be comparable to that afforded to those at risk of HNPCC. Although the risk of CRC associated with unexplained familial CRC is in general moderate, in some families the risk is substantive and likely to be the consequence of unidentified genes, as exemplified by POLE and POLD1. Our findings have utility in the design of genetic analyses to identify such novel CRC risk genes.

Spier I, Holzapfel S, Altmüller J, et al.
Frequency and phenotypic spectrum of germline mutations in POLE and seven other polymerase genes in 266 patients with colorectal adenomas and carcinomas.
Int J Cancer. 2015; 137(2):320-31 [PubMed] Related Publications
In a number of families with colorectal adenomatous polyposis or suspected Lynch syndrome/HNPCC, no germline alteration in the APC, MUTYH, or mismatch repair (MMR) genes are found. Missense mutations in the polymerase genes POLE and POLD1 have recently been identified as rare cause of multiple colorectal adenomas and carcinomas, a condition termed polymerase proofreading-associated polyposis (PPAP). The aim of the present study was to evaluate the clinical relevance and phenotypic spectrum of polymerase germline mutations. Therefore, targeted sequencing of the polymerase genes POLD1, POLD2, POLD3, POLD4, POLE, POLE2, POLE3 and POLE4 was performed in 266 unrelated patients with polyposis or fulfilled Amsterdam criteria. The POLE mutation c.1270C>G;p.Leu424Val was detected in four unrelated patients. The mutation was present in 1.5% (4/266) of all patients, 4% (3/77) of all familial cases and 7% (2/30) of familial polyposis cases. The colorectal phenotype in 14 affected individuals ranged from typical adenomatous polyposis to a HNPCC phenotype, with high intrafamilial variability. Multiple colorectal carcinomas and duodenal adenomas were common, and one case of duodenal carcinoma was reported. Additionally, various extraintestinal lesions were evident. Nine further putative pathogenic variants were identified. The most promising was c.1306C>T;p.Pro436Ser in POLE. In conclusion, a PPAP was identified in a substantial number of polyposis and familial colorectal cancer patients. Screening for polymerase proofreading mutations should therefore be considered, particularly in unexplained familial cases. The present study broadens the phenotypic spectrum of PPAP to duodenal adenomas and carcinomas, and identified novel, potentially pathogenic variants in four polymerase genes.

Yong KJ, Milenic DE, Baidoo KE, Brechbiel MW
Impact of α-targeted radiation therapy on gene expression in a pre-clinical model for disseminated peritoneal disease when combined with paclitaxel.
PLoS One. 2014; 9(9):e108511 [PubMed] Free Access to Full Article Related Publications
To better understand the molecular basis of the enhanced cell killing effected by the combined modality of paclitaxel and ²¹²Pb-trastuzumab (Pac/²¹²Pb-trastuzumab), gene expression in LS-174T i.p. xenografts was investigated 24 h after treatment. Employing a real time quantitative PCR array (qRT-PCR array), 84 DNA damage response genes were quantified. Differentially expressed genes following therapy with Pac/²¹²Pb-trastuzumab included those involved in apoptosis (BRCA1, CIDEA, GADD45α, GADD45γ, GML, IP6K3, PCBP4, PPP1R15A, RAD21, and p73), cell cycle (BRCA1, CHK1, CHK2, GADD45α, GML, GTSE1, NBN, PCBP4, PPP1R15A, RAD9A, and SESN1), and damaged DNA repair (ATRX, BTG2, EXO1, FEN1, IGHMBP2, OGG1, MSH2, MUTYH, NBN, PRKDC, RAD21, and p73). This report demonstrates that the increased stressful growth arrest conditions induced by the Pac/²¹²Pb-trastuzumab treatment suppresses cell proliferation through the regulation of genes which are involved in apoptosis and damaged DNA repair including single and double strand DNA breaks. Furthermore, the study demonstrates that ²¹²Pb-trastuzumab potentiation of cell killing efficacy results from the perturbation of genes related to the mitotic spindle checkpoint and BASC (BRCA1-associated genome surveillance complex), suggesting cross-talk between DNA damage repair and the spindle damage response.

Horpaopan S, Spier I, Zink AM, et al.
Genome-wide CNV analysis in 221 unrelated patients and targeted high-throughput sequencing reveal novel causative candidate genes for colorectal adenomatous polyposis.
Int J Cancer. 2015; 136(6):E578-89 [PubMed] Related Publications
To uncover novel causative genes in patients with unexplained adenomatous polyposis, a model disease for colorectal cancer, we performed a genome-wide analysis of germline copy number variants (CNV) in a large, well characterized APC and MUTYH mutation negative patient cohort followed by a targeted next generation sequencing (NGS) approach. Genomic DNA from 221 unrelated German patients was genotyped on high-resolution SNP arrays. Putative CNVs were filtered according to stringent criteria, compared with those of 531 population-based German controls, and validated by qPCR. Candidate genes were prioritized using in silico, expression, and segregation analyses, data mining and enrichment analyses of genes and pathways. In 27% of the 221 unrelated patients, a total of 77 protein coding genes displayed rare, nonrecurrent, germline CNVs. The set included 26 candidates with molecular and cellular functions related to tumorigenesis. Targeted high-throughput sequencing found truncating point mutations in 12% (10/77) of the prioritized genes. No clear evidence was found for autosomal recessive subtypes. Six patients had potentially causative mutations in more than one of the 26 genes. Combined with data from recent studies of early-onset colorectal and breast cancer, recurrent potential loss-of-function alterations were detected in CNTN6, FOCAD (KIAA1797), HSPH1, KIF26B, MCM3AP, YBEY and in three genes from the ARHGAP family. In the canonical Wnt pathway oncogene CTNNB1 (β-catenin), two potential gain-of-function mutations were found. In conclusion, the present study identified a group of rarely affected genes which are likely to predispose to colorectal adenoma formation and confirmed previously published candidates for tumor predisposition as etiologically relevant.

Chan N, Ali M, McCallum GP, et al.
Hypoxia provokes base excision repair changes and a repair-deficient, mutator phenotype in colorectal cancer cells.
Mol Cancer Res. 2014; 12(10):1407-15 [PubMed] Related Publications
UNLABELLED: Regions of acute and chronic hypoxia exist within solid tumors and can lead to increased rates of mutagenesis and/or altered DNA damage and repair protein expression. Base excision repair (BER) is responsible for resolving small, non-helix-distorting lesions from the genome that potentially cause mutations by mispairing or promoting DNA breaks during replication. Germline and somatic mutations in BER genes, such as MutY Homolog (MUTYH/MYH) and DNA-directed polymerase (POLB), are associated with increased risk of colorectal cancer. However, very little is known about the expression and function of BER proteins under hypoxic stress. Using conditions of chronic hypoxia, decreased expression of BER proteins was observed because of a mechanism involving suppressed BER protein synthesis in multiple colorectal cancer cell lines. Functional BER was impaired as determined by MYH- and 8-oxoguanine (OGG1)-specific glycosylase assays. A formamidopyrimidine-DNA glycosylase (Fpg) Comet assay revealed elevated residual DNA base damage in hypoxic cells 24 hours after H2O2 treatment as compared with normoxic controls. Similarly, high-performance liquid chromatography analysis demonstrated that 8-oxo-2'-deoxyguanosine lesions were elevated in hypoxic cells 3 and 24 hours after potassium bromate (KBrO3) treatment when compared with aerobic cells. Correspondingly, decreased clonogenic survival was observed following exposure to the DNA base damaging agents H2O2 and MMS, but not to the microtubule interfering agent paclitaxel. Thus, a persistent downregulation of BER components by the microenvironment modifies and facilitates a mutator phenotype, driving genetic instability and cancer progression.
IMPLICATIONS: Aberrant BER is a contributing factor for the observed genetic instability in hypoxic tumor cells.

Castillejo A, Vargas G, Castillejo MI, et al.
Prevalence of germline MUTYH mutations among Lynch-like syndrome patients.
Eur J Cancer. 2014; 50(13):2241-50 [PubMed] Related Publications
BACKGROUND AND AIMS: Individuals with tumours showing mismatch repair (MMR) deficiency not linked to germline mutations or somatic methylation of MMR genes have been recently referred as having 'Lynch-like syndrome' (LLS). The genetic basis of these LLS cases is unknown. MUTYH-associated polyposis patients show some phenotypic similarities to Lynch syndrome patients. The aim of this study was to investigate the prevalence of germline MUTYH mutations in a large series of LLS patients.
METHODS: Two hundred and twenty-five probands fulfilling LLS criteria were included in this study. Screening of MUTYH recurrent mutations, whole coding sequencing and a large rearrangement analysis were undertaken. Age, sex, clinical, pathological and molecular characteristics of tumours including KRAS mutations were assessed.
RESULTS: We found a prevalence of 3.1% of MAP syndrome in the whole series of LLS (7/225) and 3.9% when only cases fulfilling clinical criteria were considered (7/178). Patients with MUTYH biallelic mutations had more adenomas than monoallelic (P=0.02) and wildtype patients (P<0.0001). Six out of nine analysed tumours from six biallelic MUTYH carriers harboured KRAS-p.G12C mutation. This mutation was found to be associated with biallelic MUTYH germline mutation when compared with reported series of unselected colorectal cancer cohorts (P<0.0001).
CONCLUSIONS: A proportion of unexplained LLS cases is caused by biallelic MUTYH mutations. The obtained results further justify the inclusion of MUTYH in the diagnostic strategy for Lynch syndrome-suspected patients.

Shinmura K, Goto M, Tao H, et al.
Impaired 8-hydroxyguanine repair activity of MUTYH variant p.Arg109Trp found in a Japanese patient with early-onset colorectal cancer.
Oxid Med Cell Longev. 2014; 2014:617351 [PubMed] Free Access to Full Article Related Publications
PURPOSE: The biallelic inactivation of the 8-hydroxyguanine repair gene MUTYH leads to MUTYH-associated polyposis (MAP), which is characterized by colorectal multiple polyps and carcinoma(s). However, only limited information regarding MAP in the Japanese population is presently available. Since early-onset colorectal cancer (CRC) is a characteristic of MAP and might be caused by the inactivation of another 8-hydroxyguanine repair gene, OGG1, we investigated whether germline MUTYH and OGG1 mutations are involved in early-onset CRC in Japanese patients.
METHODS: Thirty-four Japanese patients with early-onset CRC were examined for germline MUTYH and OGG1 mutations using sequencing.
RESULTS: Biallelic pathogenic mutations were not found in any of the patients; however, a heterozygous p.Arg19∗  MUTYH variant and a heterozygous p.Arg109Trp MUTYH variant were detected in one patient each. The p.Arg19∗ and p.Arg109Trp corresponded to p.Arg5∗ and p.Arg81Trp, respectively, in the type 2 nuclear-form protein. The defective DNA repair activity of p.Arg5∗ is apparent, while that of p.Arg81Trp has been demonstrated using DNA cleavage and supF forward mutation assays.
CONCLUSION: These results suggest that biallelic MUTYH or OGG1 pathogenic mutations are rare in Japanese patients with early-onset CRC; however, the p.Arg19∗ and p.Arg109Trp MUTYH variants are associated with functional impairments.

Kurian AW, Hare EE, Mills MA, et al.
Clinical evaluation of a multiple-gene sequencing panel for hereditary cancer risk assessment.
J Clin Oncol. 2014; 32(19):2001-9 [PubMed] Free Access to Full Article Related Publications
PURPOSE: Multiple-gene sequencing is entering practice, but its clinical value is unknown. We evaluated the performance of a customized germline-DNA sequencing panel for cancer-risk assessment in a representative clinical sample.
METHODS: Patients referred for clinical BRCA1/2 testing from 2002 to 2012 were invited to donate a research blood sample. Samples were frozen at -80° C, and DNA was extracted from them after 1 to 10 years. The entire coding region, exon-intron boundaries, and all known pathogenic variants in other regions were sequenced for 42 genes that had cancer risk associations. Potentially actionable results were disclosed to participants.
RESULTS: In total, 198 women participated in the study: 174 had breast cancer and 57 carried germline BRCA1/2 mutations. BRCA1/2 analysis was fully concordant with prior testing. Sixteen pathogenic variants were identified in ATM, BLM, CDH1, CDKN2A, MUTYH, MLH1, NBN, PRSS1, and SLX4 among 141 women without BRCA1/2 mutations. Fourteen participants carried 15 pathogenic variants, warranting a possible change in care; they were invited for targeted screening recommendations, enabling early detection and removal of a tubular adenoma by colonoscopy. Participants carried an average of 2.1 variants of uncertain significance among 42 genes.
CONCLUSION: Among women testing negative for BRCA1/2 mutations, multiple-gene sequencing identified 16 potentially pathogenic mutations in other genes (11.4%; 95% CI, 7.0% to 17.7%), of which 15 (10.6%; 95% CI, 6.5% to 16.9%) prompted consideration of a change in care, enabling early detection of a precancerous colon polyp. Additional studies are required to quantify the penetrance of identified mutations and determine clinical utility. However, these results suggest that multiple-gene sequencing may benefit appropriately selected patients.

Liao DX, Li B, Du XM, et al.
Two Chinese pedigrees for adenomatous polyposis coli: new mutations at codon 1309 and predisposition to phenotypic variations.
Fam Cancer. 2014; 13(3):361-8 [PubMed] Related Publications
Familial adenomatous polyposis (FAP) is an autosomal dominant inherited disease caused by a mutation in the adenomatous polyposis coli (APC) gene. Some studies have attempted to correlate mutations at codon 1309 with classic FAP (≥100 colorectal polyps). We report two Chinese FAP pedigrees with new frameshift mutations at codon 1309, in which affected individuals manifest phenotypic variations. Comprehensive physical examinations were performed for all living individuals and the medical data of deceased patients were collected. Screening of the APC and human mutY homolog (MUTYH) genes for germline mutations was conducted by direct polymerase chain reaction (PCR) sequencing. In two pedigrees, a heterozygous deletion in exon 16 of the APC gene was present in all FAP patients but absent in the unaffected individuals. There were no changes to the MUTYH gene. The first pedigree, with a new frameshift mutation at c.3926_3930 del AAAAG (p. Glu1309Aspfs X4), exhibited obvious differences in the polyp number such that the proband manifested only three colorectal polyps, whereas another patients showed the symptoms of classic FAP. The second pedigree, also traced a new mutation at c.3922_3925 del AAAG (p. Glu1309Argfs X11). Although all of the patients presented with classic polyposis, one of them exhibited a delayed onset of colorectal cancer in his 50s. Two novel mutations at codon 1309 in two Chinese families suffering from FAP could enrich the germline mutation spectrum of the APC gene. Families of individuals might manifest different phenotypes, even with an identical codon 1309 mutation, unlike in previous studies.

Grasso F, Giacomini E, Sanchez M, et al.
Genetic instability in lymphoblastoid cell lines expressing biallelic and monoallelic variants in the human MUTYH gene.
Hum Mol Genet. 2014; 23(14):3843-52 [PubMed] Related Publications
The MUTYH DNA glycosylase counteracts mutagenesis by removing adenine misincorporated opposite DNA 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG). Biallelic germline mutations in MUTYH cause the autosomal recessive MUTYH-associated polyposis (MAP). The impact on genetic instability of the p.Tyr179Cys and p.Arg245His MUTYH variants was evaluated in lymphoblastoid cell lines (LCLs) derived from MAP patients and their relatives in comparison to wild-type LCLs. No difference in MUTYH expression was identified between wild type and LCLs with the p.Tyr179Cys, while the p.Arg245His mutation was associated with an unstable MUTYH protein. LCLs homozygous for the p.Tyr179Cys or the p.Arg245His variant contained increased DNA 8-oxodG levels and exhibited a mutator phenotype at the PIG-A gene. The extent of the increased spontaneous mutation frequency was 3-fold (range 1.6- to 4.6-fold) in four independent LCLs carrying the p.Tyr179Cys variant, while a larger increase (6-fold) was observed in two p.Arg245His LCLs. A similar hypermutability and S-phase delay following treatment with KBrO3 was observed in LCLs homozygous for either variant. When genetic instability was investigated in monoallelic p.Arg245His carriers, mutant frequencies showed an increase which is intermediate between wild-type and homozygous cells, whereas the mutator effect in heterozygous p.Tyr179Cys LCLs was similar to that in homozygotes. These findings indicate that the type of MUTYH mutation can affect the extent of genome instability associated with MUTYH inactivation. In addition, the mild spontaneous mutator phenotype observed in monoallelic carriers highlights the biological importance of this gene in the protection of the genome against endogenous DNA damage.

Khrunin AV, Khokhrin DV, Moisseev AA, et al.
Pharmacogenomic assessment of cisplatin-based chemotherapy outcomes in ovarian cancer.
Pharmacogenomics. 2014; 15(3):329-37 [PubMed] Related Publications
AIM: Cisplatin and its analogs are potent antitumor agents. However, their use is restricted by significant variability in tumor response and toxicity. There is a great need to identify genetic markers to predict the most important adverse events and patient outcomes.
MATERIALS & METHODS: We have evaluated the association between polymorphisms in 106 genes involved mainly in xenobiotic metabolism, DNA repair, the cell cycle and apoptosis, and outcomes in 104 ovarian cancer patients receiving cisplatin-cyclophosphamide chemotherapy. Arrayed primer extension technology was used to genotype 228 SNPs.
RESULTS: Ten SNPs in nine genes were found to be associated with one or more of the assessed clinical end points. SNPs in TPMT and NQO1 were significantly associated with progression-free survival. Polymorphisms in ERCC5, RAD52, MUTYH and LIG3 correlated with the occurrence of severe neutropenia. SNPs in NAT2 and EPHX1 were associated with anemia and nephrotoxicity, respectively. A SNP in ADH1C was correlated with complete tumor response.
CONCLUSION: The results obtained suggest that SNPs in different genes involved in drug metabolism can be important in identifying patients at risk for nonresponse to or toxicity from cisplatin-based treatment.

Morak M, Heidenreich B, Keller G, et al.
Biallelic MUTYH mutations can mimic Lynch syndrome.
Eur J Hum Genet. 2014; 22(11):1334-7 [PubMed] Article available free on PMC after 01/11/2015 Related Publications
The hallmarks of Lynch syndrome (LS) include a positive family history of colorectal cancer (CRC), germline mutations in the DNA mismatch repair (MMR) genes, tumours with high microsatellite instability (MSI-H) and loss of MMR protein expression. However, in ∼10-15% of clinically suspected LS cases, MMR mutation analyses cannot explain MSI-H and abnormal immunohistochemistry (IHC) results. The highly variable phenotype of MUTYH-associated polyposis (MAP) can overlap with the LS phenotype, but is inherited recessively. We analysed the MUTYH gene in 85 'unresolved' patients with tumours showing IHC MMR-deficiency without detectable germline mutation. Biallelic p.(Tyr179Cys) MUTYH germline mutations were found in one patient (frequency 1.18%) with CRC, urothelial carcinoma and a sebaceous gland carcinoma. LS was suspected due to a positive family history of CRC and because of MSI-H and MSH2-MSH6 deficiency on IHC in the sebaceous gland carcinoma. Sequencing of this tumour revealed two somatic MSH2 mutations, thus explaining MSI-H and IHC results, and mimicking LS-like histopathology. This is the first report of two somatic MSH2 mutations leading to an MSI-H tumour lacking MSH2-MSH6 protein expression in a patient with MAP. In addition to typical transversion mutations in KRAS and APC, MAP can also induce tumourigenesis via the MSI-pathway.

Cragun D, Radford C, Dolinsky JS, et al.
Panel-based testing for inherited colorectal cancer: a descriptive study of clinical testing performed by a US laboratory.
Clin Genet. 2014; 86(6):510-20 [PubMed] Article available free on PMC after 01/11/2015 Related Publications
Next-generation sequencing enables testing for multiple genes simultaneously ('panel-based testing') as opposed to sequential testing for one inherited condition at a time ('syndrome-based testing'). This study presents results from patients who underwent hereditary colorectal cancer (CRC) panel-based testing ('ColoNext(™) '). De-identified data from a clinical testing laboratory were used to calculate (1) frequencies for patient demographic, clinical, and family history variables and (2) rates of pathogenic mutations and variants of uncertain significance (VUS). The proportion of individuals with a pathogenic mutation who met national syndrome-based testing criteria was also determined. Of 586 patients, a pathogenic mutation was identified in 10.4%, while 20.1% had at least one VUS. After removing eight patients with CHEK2 mutations and 11 MUTYH heterozygotes, the percentage of patients with 'actionable' mutations that would clearly alter cancer screening recommendations per national guidelines decreased to 7.2%. Of 42 patients with an 'actionable' result, 30 (71%) clearly met established syndrome-based testing guidelines. This descriptive study is among the first to report on a large clinical series of patients undergoing panel-based testing for inherited CRC. Results are discussed in the context of benefits and concerns that have been raised about panel-based testing implementation.

Guarinos C, Juárez M, Egoavil C, et al.
Prevalence and characteristics of MUTYH-associated polyposis in patients with multiple adenomatous and serrated polyps.
Clin Cancer Res. 2014; 20(5):1158-68 [PubMed] Related Publications
PURPOSE: The present study aimed to determine the prevalence of MUTYH mutations in patients with multiple colonic polyps and to explore the best strategy for diagnosing MUTYH-associated polyposis (MAP) in these patients.
EXPERIMENTAL DESIGN: This study included 405 patients with at least 10 colonic polyps each. All cases were genetically tested for the three most frequent MUTYH mutations. Whole-gene analysis was performed in heterozygous patients and in 216 patients lacking the three most frequent mutations. Polyps from 56 patients were analyzed for the KRAS-Gly12Cys and BRAF V600E somatic mutations.
RESULTS: Twenty-seven (6.7%) patients were diagnosed with MAP, of which 40.8% showed serrated polyps. The sensitivity of studying only the three common variants was 74.1%. Of 216 patients without any monoallelic mutation in common variants, whole-gene analysis revealed biallelic pathogenic mutation in only one. G396D mutation was associated with serrated lesions and older age at diagnosis. There was a strong association between germinal MUTYH mutation and KRAS Gly12Cys somatic mutation in polyps. BRAF V600E mutation was found in 74% of serrated polyps in MUTYH-negative patients and in none of the polyps of MAP patients.
CONCLUSIONS: We observed a low frequency of MUTYH mutations among patients with multiple adenomatous and serrated polyps. The MAP phenotype frequently included patients with serrated polyps, especially when G396D mutation was involved. Our results show that somatic molecular markers of polyps can be useful in identifying MAP cases and support the need for the complete MUTYH gene analysis only in patients heterozygous for recurrent variants.

Win AK, Dowty JG, Cleary SP, et al.
Risk of colorectal cancer for carriers of mutations in MUTYH, with and without a family history of cancer.
Gastroenterology. 2014; 146(5):1208-11.e1-5 [PubMed] Article available free on PMC after 01/11/2015 Related Publications
We studied 2332 individuals with monoallelic mutations in MUTYH among 9504 relatives of 264 colorectal cancer (CRC) cases with a MUTYH mutation. We estimated CRC risks through 70 years of age of 7.2% for male carriers of monoallelic mutations (95% confidence interval [CI], 4.6%-11.3%) and 5.6% for female carriers of monoallelic mutations (95% CI, 3.6%-8.8%), irrespective of family history. For monoallelic MUTYH mutation carriers with a first-degree relative with CRC diagnosed by 50 years of age who does not have the MUTYH mutation, risks of CRC were 12.5% for men (95% CI, 8.6%-17.7%) and 10% for women (95% CI, 6.7%-14.4%). Risks of CRC for carriers of monoallelic mutations in MUTYH with a first-degree relative with CRC are sufficiently high to warrant more intensive screening than for the general population.

Casper M, Acalovschi M, Lammert F, Zimmer V
The MUTYH hotspot mutations p.G396D and p.Y179C do not cause substantial genetic susceptibility to biliary cancer.
Fam Cancer. 2014; 13(2):243-7 [PubMed] Related Publications
Inflammation-associated oxidative stress and DNA damage are involved in malignant transformation of cholangiocytes. Defective DNA repair mechanisms may predispose to cholangiocarcinoma (CCA) formation, and an elevated CCA risk for MutY human homologue (MUTYH) germline mutation carriers has been proposed previously. The aim of this study was to re-evaluate the MUTYH hotspot mutations p.Y179C (rs34612342) and p.G396D (rs36053993) as genetic susceptibility factors in a large CCA cohort. The study population consisted of 219 Caucasian CCA patients (66.2 ± 11.9 years, 130 males, 89 females; 43 intrahepatic and 176 extrahepatic tumours; tissue diagnosis in 77.6 %) and 355 healthy controls (61.0 ± 11.0 years; 158 males, 197 females). MUTYH hotspot variants were genotyped using TaqMan assays. Four CCA patients were monoallelic mutation carriers (3 p.G396D; 1 p.Y179C) whereas 6 control subjects were heterozygotes (5 p.G396D; 1 p.Y179C). None of the patients carried a biallelic hotspot mutation. The observed allele frequencies did not differ significantly between cases and controls (p > 0.05) and association tests did not provide evidence for an involvement of p.Y179C (OR 1.6 [95 % CI 0.1-26.0]) or p.G396D (OR 1.0 [95 % CI 0.2-4.1]) in the susceptibility to CCA. Power analysis identified a sufficient power only for large effect sizes (>90 % for OR > 5.8 for p.G396D and OR > 18.5 for p.Y179C). Monoallelic MUTYH hotspot mutations do not act as major genetic susceptibility factors causing a substantial CCA risk in the Caucasian population. Due to the low statistical power for the identification of small effect sizes, much larger studies will be needed to detect such effects of minor clinical significance.

Kong F, Han XY, Luan Y, et al.
MUTYH association with esophageal adenocarcinoma in a Han Chinese population.
Asian Pac J Cancer Prev. 2013; 14(11):6411-3 [PubMed] Related Publications
Adenocarcinoma of esophagus (AE) is a complex disease, affected by a variety of genetic and environmental factors. Much evidence has shown that the MutY glycosylase homologue (MUTYH) plays a key role in the pathogenesis of many cancers. However, there have been no reports on influence on AE in the Han Chinese population. The objective of this study was to investigate this issue. A gene-based association study was conducted using three single nucleotide polymorphisms(SNPs) reported in previous studies. The three SNPs (rs3219463, rs3219472, rs3219489) were genotyped in 207 unrelated AE patients and 249 healthy controls in a case-control study using polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP). The results revealed that the genotype distribution of rs3219472 differed between the case and control groups (OR=1.66,95%CI=1.11-2.48, P=0.012 ), indicating that an association may exist between MUTYH and AE. These findings support a signifcant role for MUTYH in AE pathogenesis in the Han Chinese population.

Yang L, Huang XE, Xu L, et al.
Role of MYH polymorphisms in sporadic colorectal cancer in China: a case-control, population-based study.
Asian Pac J Cancer Prev. 2013; 14(11):6403-9 [PubMed] Related Publications
PURPOSE: Biallelic germline variants of the 8-hydroxyguanine (8-OG) repair gene MYH have been associated with colorectal neoplasms that display somatic G:C?T:A transversions. However, the effect of single germline variants has not been widely studied, prompting the present investigation of monoallelic MYH variants and susceptibility to sporadic colorectal cancer (CRC) in a Chinese population.
PATIENTS AND METHODS: Between January 2006 and December 2012, 400 cases of sporadic CRC and 600 age- and sex-matched normal blood donors were screened randomly for 7 potentially pathogenic germline MYH exons using genetic testing technology. Variants of heterozygosity at the MYH locus were assessed in both sporadic cancer patients and healthy controls. Univariate and multivariate analyses were performed to determine risk factors for cancer onset.
RESULTS: Five monoallelic single nucleotide polymorphisms (SNPs) were identified in the 7 exon regions of MYH, which were detected in 75 (18.75%) of 400 CRC patients as well as 42 (7%) of 600 normal controls. The region of exon 1 proved to be a linked polymorphic region for the first time, a triple linked variant including exon 1-316 G?A, exon 1-292 G?A and intron 1+11 C?T, being identified in 13 CRC patients and 2 normal blood donors. A variant of base replacement, intron 10-2 A?G, was identified in the exon 10 region in 21 cases and 7 controls, while a similar type of variant in the exon 13 region, intron 13+12 C?T, was identified in 8 cases and 6 controls. Not the only but a newly missense variant in the present study, p. V463E (Exon 14+74 T?A), was identified in exon 14 in 6 patients and 1 normal control. In exon 16, nt. 1678-80 del GTT with loss of heterozygosity (LOH) was identified in 27 CRC cases and 26 controls. There was no Y165C in exon 7 or G382D in exon 14, the hot- spot variants which have been reported most frequently in Caucasian studies. After univariate analysis and multivariate analysis, the linked variant in exon 1 region (p=0.002), intron 10-2 A?G (p=0.004) and p. V463E (p=0.036) in the MYH gene were selected as 3 independent risk factors for CRC.
CONCLUSIONS: According to these results, the linked variant in Exon 1 region, Intron 10-2 A?G of base replacement and p. V463E of missense variant, the 3 heterozygosity variants of MYH gene in a Chinese population, may relate to the susceptibility to sporadic CRC. Lack of the hot-spot variants of Caucasians in the present study may due to the ethnic difference in MYH gene.

Yurgelun MB, Hornick JL, Curry VK, et al.
Therapy-associated polyposis as a late sequela of cancer treatment.
Clin Gastroenterol Hepatol. 2014; 12(6):1046-50 [PubMed] Article available free on PMC after 01/11/2015 Related Publications
Survivors of childhood cancers are at increased risk of developing secondary gastrointestinal cancers, including colorectal cancer, later in life, possibly from exposure to abdominopelvic radiotherapy and/or alkylating chemotherapy. Profuse gastrointestinal polyposis is associated with rare, inherited colorectal cancer predisposition syndromes, most commonly caused by mutations in the adenomatous polyposis coli (APC) or mutY homolog (MUTYH) genes. We describe 5 patients who developed gastrointestinal polyposis many years after radiotherapy and chemotherapy for a childhood cancer. Genetic analysis of all 5 subjects did not identify pathogenic germline mutations in APC or MUTYH. Chemotherapy and/or radiotherapy therefore might cause gastrointestinal polyposis in some patients by undiscovered mechanisms.

Hwang BJ, Shi G, Lu AL
Mammalian MutY homolog (MYH or MUTYH) protects cells from oxidative DNA damage.
DNA Repair (Amst). 2014; 13:10-21 [PubMed] Article available free on PMC after 01/11/2015 Related Publications
MutY DNA glycosylase homologs (MYH or MUTYH) reduce G:C to T:A mutations by removing misincorporated adenines or 2-hydroxyadenines paired with guanine or 8-oxo-7,8-dihydroguanine (8-oxo-G). Mutations in the human MYH (hMYH) gene are associated with the colorectal cancer predisposition syndrome MYH-associated polyposis. To examine the function of MYH in human cells, we regulated MYH gene expression by knockdown or overproduction. MYH knockdown human HeLa cells are more sensitive to the killing effects of H2O2 than the control cells. In addition, hMYH knockdown cells have altered cell morphology, display enhanced susceptibility to apoptosis, and have altered DNA signaling activation in response to oxidative stress. The cell cycle progression of hMYH knockdown cells is also different from that of the control cells following oxidative stress. Moreover, hMYH knockdown cells contain higher levels of 8-oxo-G lesions than the control cells following H2O2 treatment. Although MYH does not directly remove 8-oxo-G, MYH may generate favorable substrates for other repair enzymes. Overexpression of mouse Myh (mMyh) in human mismatch repair defective HCT15 cells makes the cells more resistant to killing and refractory to apoptosis by oxidative stress than the cells transfected with vector. In conclusion, MYH is a vital DNA repair enzyme that protects cells from oxidative DNA damage and is critical for a proper cellular response to DNA damage.

Hegde M, Ferber M, Mao R, et al.
ACMG technical standards and guidelines for genetic testing for inherited colorectal cancer (Lynch syndrome, familial adenomatous polyposis, and MYH-associated polyposis).
Genet Med. 2014; 16(1):101-16 [PubMed] Related Publications
Lynch syndrome, familial adenomatous polyposis, and Mut Y homolog (MYH)-associated polyposis are three major known types of inherited colorectal cancer, which accounts for up to 5% of all colon cancer cases. Lynch syndrome is most frequently caused by mutations in the mismatch repair genes MLH1, MSH2, MSH6, and PMS2 and is inherited in an autosomal dominant manner. Familial adenomatous polyposis is manifested as colonic polyposis caused by mutations in the APC gene and is also inherited in an autosomal dominant manner. Finally, MYH-associated polyposis is caused by mutations in the MUTYH gene and is inherited in an autosomal recessive manner but may or may not be associated with polyps. There are variants of both familial adenomatous polyposis (Gardner syndrome--with extracolonic features--and Turcot syndrome, which features medulloblastoma) and Lynch syndrome (Muir-Torre syndrome features sebaceous skin carcinomas, and Turcot syndrome features glioblastomas). Although a clinical diagnosis of familial adenomatous polyposis can be made using colonoscopy, genetic testing is needed to inform at-risk relatives. Because of the overlapping phenotypes between attenuated familial adenomatous polyposis, MYH-associated polyposis, and Lynch syndrome, genetic testing is needed to distinguish among these conditions. This distinction is important, especially for women with Lynch syndrome, who are at increased risk for gynecological cancers. Clinical testing for these genes has progressed rapidly in the past few years with advances in technologies and the lower cost of reagents, especially for sequencing. To assist clinical laboratories in developing and validating testing for this group of inherited colorectal cancers, the American College of Medical Genetics and Genomics has developed the following technical standards and guidelines. An algorithm for testing is also proposed.

Nassiri M, Kooshyar MM, Roudbar Z, et al.
Genes and SNPs associated with non-hereditary and hereditary colorectal cancer.
Asian Pac J Cancer Prev. 2013; 14(10):5609-14 [PubMed] Related Publications
BACKGROUND: Colorectal cancer is the third most common cancer in both men and women in the world and the second leading cause of cancer-related deaths. The incidence of colorectal cancer has increased in Iran in the past three decades and is now considered as a serious problem for our society. This cancer has two types hereditary and non-hereditary, 80% of cases being the latter. Considering that the relationship between SNPs with diseases is a concern, many researchers believed that they offer valuable markers for identifying genes responsible for susceptibility to common diseases. In some cases, they are direct causes of human disease. One SNP can increase risk of cancer, but when considering the rate of overlap and frequency of DNA repair pathways, it might be expected that SNP alone cannot affect the final result of cancer, although several SNPs together can exert a significant influence. Therefore identification of these SNPs is very important. The most important loci which include mutations are: MLH1, MSH2, PMS2, APC, MUTYH, SMAD7, STK11, XRCC3, DNMT1, MTHFR, Exo1, XRCC1 and VDR. Presence of SNPs in these genes decreases or increases risk of colorectal cancer.
MATERIALS AND METHODS: In this article we reviewed the Genes and SNPs associated with non-hereditary and hereditary of colorectal cancer that recently were reported from candidate gene y, meta-analysis and GWAS studies.
RESULTS: As with other cancers, colorectal cancer is associated with SNPs in gene loci. Generally, by exploring SNPs, it is feasible to predict the risk of developing colorectal cancer and thus establishing proper preventive measures.
CONCLUSIONS: SNPs of genes associated with colorectal cancer can be used as a marker SNP panel as a potential tool for improving cancer diagnosis and treatment planning.

De Lellis L, Aceto GM, Curia MC, et al.
Integrative analysis of hereditary nonpolyposis colorectal cancer: the contribution of allele-specific expression and other assays to diagnostic algorithms.
PLoS One. 2013; 8(11):e81194 [PubMed] Article available free on PMC after 01/11/2015 Related Publications
The identification of germline variants predisposing to hereditary nonpolyposis colorectal cancer (HNPCC) is crucial for clinical management of carriers, but several probands remain negative for such variants or bear variants of uncertain significance (VUS). Here we describe the results of integrative molecular analyses in 132 HNPCC patients providing evidences for improved genetic testing of HNPCC with traditional or next generation methods. Patients were screened for: germline allele-specific expression (ASE), nucleotide variants, rearrangements and promoter methylation of mismatch repair (MMR) genes; germline EPCAM rearrangements; tumor microsatellite instability (MSI) and immunohistochemical (IHC) MMR protein expression. Probands negative for pathogenic variants of MMR genes were screened for germline APC and MUTYH sequence variants. Most germline defects identified were sequence variants and rearrangements of MMR genes. Remarkably, altered germline ASE of MMR genes was detected in 8/22 (36.5%) probands analyzed, including 3 cases negative at other screenings. Moreover, ASE provided evidence for the pathogenic role and guided the characterization of a VUS shared by 2 additional probands. No germline MMR gene promoter methylation was observed and only one EPCAM rearrangement was detected. In several cases, tumor IHC and MSI diverged from germline screening results. Notably, APC or biallelic MUTYH germline defects were identified in 2/19 probands negative for pathogenic variants of MMR genes. Our results show that ASE complements gDNA-based analyses in the identification of MMR defects and in the characterization of VUS affecting gene expression, increasing the number of germline alterations detected. An appreciable fraction of probands negative for MMR gene variants harbors APC or MUTYH variants. These results indicate that germline ASE analysis and screening for APC and MUTYH defects should be included in HNPCC diagnostic algorithms.

Hes FJ, Ruano D, Nieuwenhuis M, et al.
Colorectal cancer risk variants on 11q23 and 15q13 are associated with unexplained adenomatous polyposis.
J Med Genet. 2014; 51(1):55-60 [PubMed] Article available free on PMC after 01/11/2015 Related Publications
BACKGROUND: Colorectal adenomatous polyposis is associated with a high risk of colorectal cancer (CRC) and is frequently caused by germline mutations in APC or MUTYH. However, in about 20-30% of patients no underlying gene defect can be identified. In this study, we tested if recently identified CRC risk variants play a role in patients with >10 adenomas.
METHODS: We analysed a total of 16 SNPs with a reported association with CRC in a cohort of 252 genetically unexplained index patients with >10 colorectal adenomas and 745 controls. In addition, we collected detailed clinical information from index patients and their first-degree relatives (FDRs).
RESULTS: We found a statistically significant association with two of the variants tested: rs3802842 (at chromosome 11q23, OR=1.60, 95% CI 1.3 to 2.0) and rs4779584 (at chromosome 15q13, OR=1.50, 95% CI 1.2 to 1.9). The majority of index patients (84%) had between 10 and 100 adenomas and 15% had >100 adenomas. Only two index patients (1%), both with >100 adenomas, had FDRs with polyposis. Forty-one per cent of the index patients had one or more FDRs with CRC.
CONCLUSIONS: These SNPs are the first common, low-penetrant variants reported to be associated with adenomatous polyposis not caused by a defect in the APC, MUTYH, POLD1 and POLE genes. Even though familial occurrence of polyposis was very rare, CRC was over-represented in FDRs of polyposis patients and, if confirmed, these relatives will therefore benefit from surveillance.

Hosono S, Matsuo K, Ito H, et al.
Polymorphisms in base excision repair genes are associated with endometrial cancer risk among postmenopausal Japanese women.
Int J Gynecol Cancer. 2013; 23(9):1561-8 [PubMed] Related Publications
OBJECTIVES: Polymorphisms in base excision repair (BER) genes are associated with risk for several types of cancers but have not been studied with respect to endometrial cancer among Japanese women. Therefore, we conducted a case-control study to explore the association between polymorphisms in BER genes and the risk for endometrial cancer.
METHODS/MATERIALS: This study included a total of 91 postmenopausal subjects with endometrial cancer and 261 controls without cancer who visited the Aichi Cancer Center between 2001 and 2005. We focused on single nucleotide polymorphisms within coding regions of 5 BER genes (OGG1, MUTYH, XRCC1, APEX1, and PARP1). To assess lifestyle in the etiology of endometrial cancer, we used a self-administered questionnaire. Associations were evaluated using multivariate unconditional logistic regression models. We also assessed whether there were intergenic associations or an interaction with obesity.
RESULTS: We observed a significant association between endometrial cancer risk and XRCC1 rs1799782 (C > T, Arg194Trp) and XRCC1 rs25487 (G > A, Arg399Gln). We uncovered a significant association between obesity (body mass index, ≥ 25) and rs25487. The XRCC1 polymorphisms were in complete linkage disequilibrium, and the XRCC1 haplotype TG associated significantly with endometrial cancer risk. The interaction between the CA haplotype and body mass index was marginally significant, whereas interaction between haplotype in XRCC1 and rs1136410 (PARP1) was not significant.
CONCLUSIONS: We found a significant association between endometrial cancer risk and XRCC1 polymorphisms and haplotype TG in postmenopausal Japanese women.

Picelli S, Lorenzo Bermejo J, Chang-Claude J, et al.
Meta-analysis of mismatch repair polymorphisms within the cogent consortium for colorectal cancer susceptibility.
PLoS One. 2013; 8(9):e72091 [PubMed] Article available free on PMC after 01/11/2015 Related Publications
In the last four years, Genome-Wide Association Studies (GWAS) have identified sixteen low-penetrance polymorphisms on fourteen different loci associated with colorectal cancer (CRC). Due to the low risks conferred by known common variants, most of the 35% broad-sense heritability estimated by twin studies remains unexplained. Recently our group performed a case-control study for eight Single Nucleotide Polymorphisms (SNPs) in 4 CRC genes. The present investigation is a follow-up of that study. We have genotyped six SNPs that showed a positive association and carried out a meta-analysis based on eight additional studies comprising in total more than 8000 cases and 6000 controls. The estimated recessive odds ratio for one of the SNPs, rs3219489 (MUTYH Q338H), decreased from 1.52 in the original Swedish study, to 1.18 in the Swedish replication, and to 1.08 in the initial meta-analysis. Since the corresponding summary probability value was 0.06, we decided to retrieve additional information for this polymorphism. The incorporation of six further studies resulted in around 13000 cases and 13000 controls. The newly updated OR was 1.03. The results from the present large, multicenter study illustrate the possibility of decreasing effect sizes with increasing samples sizes. Phenotypic heterogeneity, differential environmental exposures, and population specific linkage disequilibrium patterns may explain the observed difference of genetic effects between Sweden and the other investigated cohorts.

Corral R, Lewinger JP, Joshi AD, et al.
Genetic variation in the base excision repair pathway, environmental risk factors, and colorectal adenoma risk.
PLoS One. 2013; 8(8):e71211 [PubMed] Article available free on PMC after 01/11/2015 Related Publications
Cigarette smoking, high alcohol intake, and low dietary folate levels are risk factors for colorectal adenomas. Oxidative damage caused by these three factors can be repaired through the base excision repair pathway (BER). We hypothesized that genetic variation in BER might modify colorectal adenoma risk. In a sigmoidoscopy-based study, we examined associations between 182 haplotype tagging SNPs in 14 BER genes, and colorectal adenoma risk, and examined their potential role as modifiers of the effect cigarette smoking, alcohol intake, and dietary folate levels. Among all individuals, no statistically significant associations between BER SNPs and adenoma risk persisted after correction for multiple comparisons. However, among Asian-Pacific Islanders we observed two SNPs in FEN1 and one in NTHL1, and among African-Americans one SNP in APEX1 that were associated with colorectal adenoma risk. Significant associations were also observed between SNPs in the NEIL2 gene and rectal adenoma risk. Three SNPS modified the effect of smoking (MUTYH interaction p = 0.002; OGG1 interaction p = 0.013); FEN1 interaction p = 0.013)), one SNP in LIG3 modified the effect of alcohol consumption (interaction p = 0.024) and two SNPs in LIG3 modified the effect of dietary folate (interaction p = 0.001 and p = 0.08) on colorectal adenoma risk. These findings support a role for genetic variants in the BER pathway as potential modifiers of colorectal adenoma risk. Our findings strengthen the role of oxidative damage induced by key lifestyle and dietary risk factors in colorectal adenoma formation.

Ma X, Zhang B, Zheng W
Genetic variants associated with colorectal cancer risk: comprehensive research synopsis, meta-analysis, and epidemiological evidence.
Gut. 2014; 63(2):326-36 [PubMed] Article available free on PMC after 01/11/2015 Related Publications
OBJECTIVE: In the past two decades, approximately 1000 reports have been published regarding associations between genetic variants in candidate genes and risk of colorectal cancer (CRC). Study results are inconsistent. We aim to provide a synopsis of the current understanding of genetic factors for CRC risk through systematically evaluating results from previous studies.
DESIGN: We searched PubMed and Google Scholar to identify papers that investigated associations between genetic variants and CRC risk and published through 25 December 2012. With data from 950 papers, we conducted 910 meta-analyses for 267 genetic variants in 150 candidate genes with at least three data sources. We used Venice criteria and false-positive report probability tests to grade levels of cumulative epidemiological evidence of significant associations with CRC risk.
RESULTS: Sixty-two variants in 50 candidate genes showed a nominally significant association with CRC risk (p<0.05). Cumulative epidemiological evidence for a significant association with CRC risk was graded strong for eight variants in five genes (adenomatous polyposis coli (APC), CHEK2, DNMT3B, MLH1 and MUTYH), moderate for two variants in two genes (GSTM1 and TERT), and weak for 52 variants in 45 genes. Additionally, 40 variants in 33 genes showed convincing evidence of no association with CRC risk in meta-analyses including at least 5000 cases and 5000 controls.
CONCLUSIONS: Approximately 4% of genetic variants evaluated to date in candidate-gene association studies showed moderate to strong cumulative epidemiological evidence of an association with CRC risk. These genetic variants, if confirmed, may explain approximately 5% of familial CRC risk.

Mahdi KM, Nassiri MR, Nasiri K
Hereditary genes and SNPs associated with breast cancer.
Asian Pac J Cancer Prev. 2013; 14(6):3403-9 [PubMed] Related Publications
Breast cancer is the most common cancer among women affecting up to one third of tehm during their lifespans. Increased expression of some genes due to polymorphisms increases the risk of breast cancer incidence. Since mutations that are recognized to increase breast cancer risk within families are quite rare, identification of these SNPs is very important. The most important loci which include mutations are; BRCA1, BRCA2, PTEN, ATM, TP53, CHEK2, PPM1D, CDH1, MLH1, MRE11, MSH2, MSH6, MUTYH, NBN, PMS1, PMS2, BRIP1, RAD50, RAD51C, STK11 and BARD1. Presence of SNPs in these genes increases the risk of breast cancer and associated diagnostic markers are among the most reliable for assessing prognosis of breast cancer. In this article we reviewed the hereditary genes of breast cancer and SNPs associated with increasing the risk of breast cancer that were recently were reported from candidate gene, meta-analysis and GWAS studies. SNPs of genes associated with breast cancer can be used as a potential tool for improving cancer diagnosis and treatment planning.

Smith CG, West H, Harris R, et al.
Role of the oxidative DNA damage repair gene OGG1 in colorectal tumorigenesis.
J Natl Cancer Inst. 2013; 105(16):1249-53 [PubMed] Related Publications
Biallelic inherited mutations in the oxidative DNA damage repair gene MUTYH predispose to colorectal adenomas and colorectal carcinoma (CRC) with high penetrance. We investigated whether rare inherited variants in other oxidative DNA damage repair genes predisposed to CRC. Single marker association analyses were assessed under an allelic model with Bonferroni correction for multiple testing. All statistical tests were two-sided. A rare inherited nonsynonymous variant in OGG1 (Gly308Glu), the functional partner of MUTYH, was over-represented in case patients with advanced CRC compared with population-based control subjects (n = 36 of 2142 case patients vs n = 15 of 2175 control subjects in the training phase, P = 1.8×10(-3); and n = 22 of 1005 case patients vs n = 8 of 1389 control subjects in the validation phase, P = 4.8×10(-4); P = 1.4×10(-5) combined; odds ratio = 2.92, 95% confidence interval = 1.80 to 4.74). Glycine at residue 308 was highly conserved through evolution, and the glutamic acid substitution was predicted as likely to interfere with function. Biallelic inherited and somatic OGG1 mutations were rarely observed in OGG1 (Gly308Glu) carriers, nor did we find any associated somatic mutator phenotype. These data suggest that OGG1 (Gly308Glu) may act as a low-penetrance allele that contributes to colorectal tumorigenesis.

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