Gene Summary

Gene:FANCG; Fanconi anemia complementation group G
Aliases: FAG, XRCC9
Summary:The Fanconi anemia complementation group (FANC) currently includes FANCA, FANCB, FANCC, FANCD1 (also called BRCA2), FANCD2, FANCE, FANCF, FANCG, FANCI, FANCJ (also called BRIP1), FANCL, FANCM and FANCN (also called PALB2). The previously defined group FANCH is the same as FANCA. Fanconi anemia is a genetically heterogeneous recessive disorder characterized by cytogenetic instability, hypersensitivity to DNA crosslinking agents, increased chromosomal breakage, and defective DNA repair. The members of the Fanconi anemia complementation group do not share sequence similarity; they are related by their assembly into a common nuclear protein complex. This gene encodes the protein for complementation group G. [provided by RefSeq, Jul 2008]
Databases:VEGA, OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:Fanconi anemia group G protein
Source:NCBIAccessed: 15 March, 2017


What does this gene/protein do?
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Pathways:What pathways are this gene/protein implicaed in?
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Cancer Overview

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Publications Per Year (1992-2017)
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Literature Analysis

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Specific Cancers (1)

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Fanconi Anemia - Complementation Group G

Latest Publications

Esmail Nia G, Fadaee M, Royer R, et al.
Profiling Fanconi Anemia Gene Mutations among Iranian Patients.
Arch Iran Med. 2016; 19(4):236-40 [PubMed] Related Publications
BACKGROUND: Fanconi anemia (FA) is a rare genetic syndrome characterized by developmental defects, bone marrow failure, and a high cancer risk. FA is usually inherited as an autosomal recessive condition. This disease is genetically heterogeneous and mutations in 16 different genes have been identified in FA patients to date. An accurate diagnosis needs detection of pathogenic variations in the FA genes along with positive results from chromosome breakage test.
METHODS: In this study, 48 families with at least 2 affected FA patients and positive chromosome breakage test were enrolled from the Iranian population. Molecular analysis of FA genes was performed using Next Generation Sequencing (NGS) method and Multiple Ligation Dependent Probe Amplification (MLPA).
RESULTS: Causal mutations for 30 (63%) patients were identified in homozygous or compound heterozygous forms. FANCA had the highest mutation frequency rate (83%) followed by FANCG (10%), FANCD2 (3%) and FANCL (3%). A significant proportion (44%) of FANCA mutations were large rearrangements.
CONCLUSION: Genetic testing for FA patients improves the accuracy of diagnosis and also will be essential for genetic counselling and prenatal diagnosis for future pregnancies in the family. Availability of NGS technology has made the screening of all known FA genes at once more practical and affordable.

Ghazwani Y, AlBalwi M, Al-Abdulkareem I, et al.
Clinical characteristics and genetic subtypes of Fanconi anemia in Saudi patients.
Cancer Genet. 2016; 209(4):171-6 [PubMed] Related Publications
We reviewed our institutional experience from 2011 to 2015 on new cases of Fanconi anemia (FA). Ten unrelated cases were diagnosed during this period. Four patients with severe aplastic anemia (SAA) had c.2392C > T (p.Arg798*) BRIP1/FANCJ mutation. Another child with SAA had novel c.1475T > C (p.Leu492Pro) FANCC mutation. One individual with SAA and acute myeloid leukemia had c.637_643del (p.Tyr213Lysfs*6) FANCG mutation. Three patients presented with early onset of cancer, two had BRCA2 mutation c.7007G > A (p.Arg2336His) and one had a novel c.3425del (p.Leu1142Tyrfs*21) PALB2 mutation. Another infant with c.3425del PALB2 mutation had clonal aberration with partial trisomy of the long arm of chromosome 17. Mutations in FA downstream pathway genes are more frequent in our series than expected. Our preliminary observation will be confirmed in a large multi-institutional study.

Nicchia E, Benedicenti F, De Rocco D, et al.
Clinical aspects of Fanconi anemia individuals with the same mutation of FANCF identified by next generation sequencing.
Birth Defects Res A Clin Mol Teratol. 2015; 103(12):1003-10 [PubMed] Related Publications
BACKGROUND: Fanconi anemia (FA) is a rare genetic disease characterized by congenital malformations, aplastic anemia and increased risk of developing malignancies. FA is genetically heterogeneous as it is caused by at least 17 different genes. Among these, FANCA, FANCC, and FANCG account for approximately 85% of the patients whereas the remaining genes are mutated in only a small percentage of cases. For this reason, the molecular diagnostic process is complex and not always extended to all the FA genes, preventing the characterization of individuals belonging to rare groups.
METHODS: The FA genes were analyzed using a next generation sequencing approach in two unrelated families.
RESULTS: The analysis identified the same, c.484_485del, homozygous mutation of FANCF in both families. A careful examination of three electively aborted fetuses in one family and one affected girl in the other indicated an association of the FANCF loss-of-function mutation with a severe phenotype characterized by multiple malformations.
CONCLUSION: The systematic use of next generation sequencing will allow the recognition of individuals from rare complementation groups, a better definition of their clinical phenotypes, and consequently, an appropriate genetic counseling.

Lambert MW
Functional Significance of Nuclear α Spectrin.
J Cell Biochem. 2015; 116(9):1816-30 [PubMed] Related Publications
Nonerythroid alpha spectrin (αIISp) interacts in the nucleus with an array of different proteins indicating its involvement in a number of diverse functions. However, the significance of these interactions and their functional importance has been a relatively unexplored area. The best documented role of nuclear αIISp is in DNA repair where it is critical for repair of DNA interstrand cross-links (ICLs), acting as a scaffold recruiting proteins to sites of damage in genomic and telomeric DNA. A deficiency in αIISp can importantly impact DNA ICL repair as is seen in cells from patients with the genetic disorder, Fanconi anemia (FA), where loss of αIISp leads to not only defects in repair of both genomic and telomeric DNA but also to telomere dysfunction and chromosome instability. This previously unexplored link between αIISp and telomere function is important in developing an understanding of maintenance of genomic stability after ICL damage. In FA cells, these defects in chromosome instability after ICL damage can be corrected when levels of αIISp are returned to normal by knocking down μ-calpain, a protease which cleaves αIISp. These studies suggest a new direction for correcting a number of the phenotypic defects in FA and could serve as a basis for therapeutic intervention. More in depth, examination of the interactions of αIISp with other proteins in the nucleus is of major importance in development of insights into the interacting key elements involved in the diverse processes occurring in the nucleus and the consequences loss of αIISp has on them.

Park J, Kim M, Jang W, et al.
Founder haplotype analysis of Fanconi anemia in the Korean population finds common ancestral haplotypes for a FANCG variant.
Ann Hum Genet. 2015; 79(3):153-61 [PubMed] Related Publications
A common ancestral haplotype is strongly suggested in the Korean and Japanese patients with Fanconi anemia (FA), because common mutations have been frequently found: c.2546delC and c.3720_3724delAAACA of FANCA; c.307+1G>C, c.1066C>T, and c.1589_1591delATA of FANCG. Our aim in this study was to investigate the origin of these common mutations of FANCA and FANCG. We genotyped 13 FA patients consisting of five FA-A patients and eight FA-G patients from the Korean FA population. Microsatellite markers used for haplotype analysis included four CA repeat markers which are closely linked with FANCA and eight CA repeat markers which are contiguous with FANCG. As a result, Korean FA-A patients carrying c.2546delC or c.3720_3724delAAACA did not share the same haplotypes. However, three unique haplotypes carrying c.307+1G>C, c.1066C > T, or c.1589_1591delATA, that consisted of eight polymorphic loci covering a flanking region were strongly associated with Korean FA-G, consistent with founder haplotypes reported previously in the Japanese FA-G population. Our finding confirmed the common ancestral haplotypes on the origins of the East Asian FA-G patients, which will improve our understanding of the molecular population genetics of FA-G. To the best of our knowledge, this is the first report on the association between disease-linked mutations and common ancestral haplotypes in the Korean FA population.

Feben C, Kromberg J, Wainwright R, et al.
Hematological consequences of a FANCG founder mutation in Black South African patients with Fanconi anemia.
Blood Cells Mol Dis. 2015; 54(3):270-4 [PubMed] Related Publications
Fanconi anemia (FA) is a rare disorder of DNA repair, associated with various somatic abnormalities but characterized by hematological disease that manifests as bone marrow aplasia and malignancy. The mainstay of treatment, in developed nations, is hematopoietic stem cell transplantation (HSCT) with subsequent surveillance for solid organ and non-hematological malignancies. In South Africa, FA in the Black population is caused by a homozygous deletion mutation in the FANCG gene in more than 80% of cases. Many affected patients are not diagnosed until late in the disease course when severe cytopenia and bone marrow aplasia are already present. Most patients are not eligible for HSCT at this late stage of the disease, even when it is available in the state health care system. In this study, the hematological presentation and disease progression in 30 Black South African patients with FA, confirmed to have the FANCG founder mutation, were evaluated and compared to those described in other FA cohorts. Our results showed that patients, homozygous for the FANCG founder mutation, present with severe cytopenia but progress to bone marrow failure at similar ages to other individuals affected with FA of heterogeneous genotype. Further, the incidence of myelodysplastic syndrome is similar to that which has been previously described in other FA cohorts. Although severe cytopenia at presentation may be predicted by a higher number of somatic anomalies, the recognition of the physical FA phenotype in Black South African patients is challenging and may not be useful in expediting referral of suspected FA patients for tertiary level investigations and care. Given the late but severe hematological presentation of FA in Black South African patients, an investigative strategy is needed for earlier recognition of affected individuals to allow for possible HSCT and management of bone marrow disease.

Young A, Berry R, Holloway AF, et al.
RNA-seq profiling of a radiation resistant and radiation sensitive prostate cancer cell line highlights opposing regulation of DNA repair and targets for radiosensitization.
BMC Cancer. 2014; 14:808 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Radiotherapy is a chosen treatment option for prostate cancer patients and while some tumours respond well, up to 50% of patients may experience tumour recurrence. Identification of functionally relevant predictive biomarkers for radioresponse in prostate cancer would enable radioresistant patients to be directed to more appropriate treatment options, avoiding the side-effects of radiotherapy.
METHODS: Using an in vitro model to screen for novel biomarkers of radioresistance, transcriptome analysis of a radioresistant (PC-3) and radiosensitive (LNCaP) prostate cancer cell line was performed. Following pathway analysis candidate genes were validated using qRT-PCR. The DNA repair pathway in radioresistant PC-3 cells was then targeted for radiation sensitization using the PARP inhibitor, niacinimide.
RESULTS: Opposing regulation of a DNA repair and replication pathway was observed between PC-3 and LNCaP cells from RNA-seq analysis. Candidate genes BRCA1, RAD51, FANCG, MCM7, CDC6 and ORC1 were identified as being significantly differentially regulated post-irradiation. qRT-PCR validation confirmed BRCA1, RAD51 and FANCG as being significantly differentially regulated at 24 hours post radiotherapy (p-value =0.003, 0.045 and 0.003 respectively). While the radiosensitive LNCaP cells down-regulated BRCA1, FANCG and RAD51, the radioresistant PC-3 cell line up-regulated these candidates to promote cell survival post-radiotherapy and a similar trend was observed for MCM7, CDC6 and ORC1. Inhibition of DNA repair using niacinamide sensitised the radioresistant cells to irradiation, reducing cell survival at 2 Gy from 66% to 44.3% (p-value =0.02).
CONCLUSIONS: These findings suggest that the DNA repair candidates identified via RNA-seq hold potential as both targets for radiation sensitization and predictive biomarkers in prostate cancer.

Zhu B, Yan K, Li L, et al.
K63-linked ubiquitination of FANCG is required for its association with the Rap80-BRCA1 complex to modulate homologous recombination repair of DNA interstand crosslinks.
Oncogene. 2015; 34(22):2867-78 [PubMed] Related Publications
DNA interstrand crosslinks (ICLs) are extremely deleterious lesions that are repaired by homologous recombination (HR) through coordination of Fanconi anemia (FA) proteins and breast cancer susceptibility gene 1 (BRCA1) product, but the exact role these proteins have remains unclear. Here we report that FANCG was modified by the addition of lysine63-linked polyubiquitin chains (K63Ub) in response to DNA damage. We show that FANCG K63Ub was dispensable for monoubiquitination of FANCD2, but was required for FANCG to interact with the Rap80-BRCA1 (receptor-associated protein 80-BRCA1) complex for subsequent modulation of HR repair of ICLs induced by mitomycin C. Mutation of three lysine residues within FANCG to arginine (K182, K258 and K347, 3KR) reduced FANCG K63Ub modification, as well as its interaction with the Rap80-BRCA1 complex, and therefore impeded HR repair. In addition, we demonstrated that K63Ub-modified FANCG was deubiquitinated by BRCC36 complex in vitro and in vivo. Inhibition of BRCC36 resulted in increased K63Ub modification of FANCG. Taken together, our results identify a new role of FANCG in HR repair of ICL through K63Ub-mediated interaction with the Rap80-BRCA1 complex.

Mantere T, Haanpää M, Hanenberg H, et al.
Finnish Fanconi anemia mutations and hereditary predisposition to breast and prostate cancer.
Clin Genet. 2015; 88(1):68-73 [PubMed] Related Publications
Mutations in downstream Fanconi anemia (FA) pathway genes, BRCA2, PALB2, BRIP1 and RAD51C, explain part of the hereditary breast cancer susceptibility, but the contribution of other FA genes has remained questionable. Due to FA's rarity, the finding of recurrent deleterious FA mutations among breast cancer families is challenging. The use of founder populations, such as the Finns, could provide some advantage in this. Here, we have resolved complementation groups and causative mutations of five FA patients, representing the first mutation confirmed FA cases in Finland. These patients belonged to complementation groups FA-A (n = 3), FA-G (n = 1) and FA-I (n = 1). The prevalence of the six FA causing mutations was then studied in breast (n = 1840) and prostate (n = 565) cancer cohorts, and in matched controls (n = 1176 females, n = 469 males). All mutations were recurrent, but no significant association with cancer susceptibility was observed for any: the prevalence of FANCI c.2957_2969del and c.3041G>A mutations was even highest in healthy males (1.7%). This strengthens the exclusive role of downstream genes in cancer predisposition. From a clinical point of view, current results provide fundamental information of the mutations to be tested first in all suspected FA cases in Finland.

Nguyen TV, Riou L, Aoufouchi S, Rosselli F
Fanca deficiency reduces A/T transitions in somatic hypermutation and alters class switch recombination junctions in mouse B cells.
J Exp Med. 2014; 211(6):1011-8 [PubMed] Free Access to Full Article Related Publications
Fanconi anemia is a rare genetic disorder that can lead to bone marrow failure, congenital abnormalities, and increased risk for leukemia and cancer. Cells with loss-of-function mutations in the FANC pathway are characterized by chromosome fragility, altered mutability, and abnormal regulation of the nonhomologous end-joining (NHEJ) pathway. Somatic hypermutation (SHM) and immunoglobulin (Ig) class switch recombination (CSR) enable B cells to produce high-affinity antibodies of various isotypes. Both processes are initiated after the generation of dG:dU mismatches by activation-induced cytidine deaminase. Whereas SHM involves an error-prone repair process that introduces novel point mutations into the Ig gene, the mismatches generated during CSR are processed to create double-stranded breaks (DSBs) in DNA, which are then repaired by the NHEJ pathway. As several lines of evidence suggest a possible role for the FANC pathway in SHM and CSR, we analyzed both processes in B cells derived from Fanca(-/-) mice. Here we show that Fanca is required for the induction of transition mutations at A/T residues during SHM and that despite globally normal CSR function in splenic B cells, Fanca is required during CSR to stabilize duplexes between pairs of short microhomology regions, thereby impeding short-range recombination downstream of DSB formation.

De Rocco D, Bottega R, Cappelli E, et al.
Molecular analysis of Fanconi anemia: the experience of the Bone Marrow Failure Study Group of the Italian Association of Pediatric Onco-Hematology.
Haematologica. 2014; 99(6):1022-31 [PubMed] Free Access to Full Article Related Publications
Fanconi anemia is an inherited disease characterized by congenital malformations, pancytopenia, cancer predisposition, and sensitivity to cross-linking agents. The molecular diagnosis of Fanconi anemia is relatively complex for several aspects including genetic heterogeneity with mutations in at least 16 different genes. In this paper, we report the mutations identified in 100 unrelated probands enrolled into the National Network of the Italian Association of Pediatric Hematoly and Oncology. In approximately half of these cases, mutational screening was carried out after retroviral complementation analyses or protein analysis. In the other half, the analysis was performed on the most frequently mutated genes or using a next generation sequencing approach. We identified 108 distinct variants of the FANCA, FANCG, FANCC, FANCD2, and FANCB genes in 85, 9, 3, 2, and 1 families, respectively. Despite the relatively high number of private mutations, 45 of which are novel Fanconi anemia alleles, 26% of the FANCA alleles are due to 5 distinct mutations. Most of the mutations are large genomic deletions and nonsense or frameshift mutations, although we identified a series of missense mutations, whose pathogenetic role was not always certain. The molecular diagnosis of Fanconi anemia is still a tiered procedure that requires identifying candidate genes to avoid useless sequencing. Introduction of next generation sequencing strategies will greatly improve the diagnostic process, allowing a rapid analysis of all the genes.

Wainstein T, Kerr R, Mitchell CL, et al.
Fanconi anaemia in black South African patients heterozygous for the FANCG c.637-643delTACCGCC founder mutation.
S Afr Med J. 2013; 103(12 Suppl 1):970-3 [PubMed] Related Publications
BACKGROUND: Fanconi anaemia (FA) is an autosomal recessive, genetically heterogeneous disorder, characterised by interstrand crosslink-induced chromosome breaks, congenital abnormalities and predisposition to malignancies. It has a prevalence of about 1/40 000 in black South Africans (SAs). A founder mutation in the FANCG gene occurs in the homozygous state in 77.5% of southern African blacks.
OBJECTIVE: To locate additional pathogenic mutations in the FANCG gene of black FA patients who were heterozygous for the founder mutation. Methods. Further mutation analysis of the FANCG gene was undertaken in 7 patients clinically suspected of having FA. The parents of two of the patients were tested for the presence of the founder mutation to determine true heterozygosity in the patients. To clarify whether or not previously unreported variants were pathogenic, 58 random black SA individuals were screened.
RESULTS: Three novel single base pair deletions, resulting in frameshift mutations (c.247delA, c.179delT and c.899delT) were identified in 3/7 patients. A fourth patient was found to have a single base substitution resulting in a splice site mutation (c.1636+1G>A). The remaining three patients were not found to harbour any pathogenic mutations. Two non-pathogenic variants were also identified among the seven patients.
CONCLUSION: The results of this small sample suggest that a second common mutation in the FANCG gene is unlikely in this population. However, FANCG sequencing should be performed on patients heterozygous for the common founder mutation to attempt to confirm their diagnosis.

Ghosh S, Sur S, Yerram SR, et al.
Hypersensitivities for acetaldehyde and other agents among cancer cells null for clinically relevant Fanconi anemia genes.
Am J Pathol. 2014; 184(1):260-70 [PubMed] Free Access to Full Article Related Publications
Large-magnitude numerical distinctions (>10-fold) among drug responses of genetically contrasting cancers were crucial for guiding the development of some targeted therapies. Similar strategies brought epidemiological clues and prevention goals for genetic diseases. Such numerical guides, however, were incomplete or low magnitude for Fanconi anemia pathway (FANC) gene mutations relevant to cancer in FANC-mutation carriers (heterozygotes). We generated a four-gene FANC-null cancer panel, including the engineering of new PALB2/FANCN-null cancer cells by homologous recombination. A characteristic matching of FANCC-null, FANCG-null, BRCA2/FANCD1-null, and PALB2/FANCN-null phenotypes was confirmed by uniform tumor regression on single-dose cross-linker therapy in mice and by shared chemical hypersensitivities to various inter-strand cross-linking agents and γ-radiation in vitro. Some compounds, however, had contrasting magnitudes of sensitivity; a strikingly high (19- to 22-fold) hypersensitivity was seen among PALB2-null and BRCA2-null cells for the ethanol metabolite, acetaldehyde, associated with widespread chromosomal breakage at a concentration not producing breaks in parental cells. Because FANC-defective cancer cells can share or differ in their chemical sensitivities, patterns of selective hypersensitivity hold implications for the evolutionary understanding of this pathway. Clinical decisions for cancer-relevant prevention and management of FANC-mutation carriers could be modified by expanded studies of high-magnitude sensitivities.

Feben C, Kromberg J, Wainwright R, et al.
Phenotypic consequences in black South African Fanconi anemia patients homozygous for a founder mutation.
Genet Med. 2014; 16(5):400-6 [PubMed] Related Publications
PURPOSE: Fanconi anemia is a genotypically and phenotypically heterogeneous condition, characterized microscopically by chromosomal instability and breakage. Affected individuals manifest growth restriction and congenital physical abnormalities; most progress to hematological disease including bone marrow aplasia. Black South African Fanconi anemia patients share a common causative founder mutation in the Fanconi G gene in 80% of cases (637_643delTACCGCC). The aim of this study was to investigate the genotype-physical phenotype correlation in a cohort of individuals homozygous for this mutation.
METHODS: Thirty-five black patients were recruited from tertiary level hematology/oncology clinics in South Africa. Participants were subjected to a comprehensive clinical examination, documenting growth, congenital anomalies, and phenotypic variability.
RESULTS: Descriptive statistical analysis showed significant growth abnormalities in many patients and a high frequency (97%) of skin pigmentary anomalies. Subtle anomalies of the eyes, ears, and hands occurred frequently (≥70%). Apart from malformations of the kidney (in 37%) and gastrointestinal tract (in 8.5%), congenital anomalies of other systems including the cardiovascular and central nervous systems, genitalia, and vertebrae were infrequent (<5%).
CONCLUSION: The diagnosis of Fanconi anemia in black South African patients before the onset of hematological symptoms remains a clinical challenge, with the physical phenotype unlikely to be recognized by those without dysmorphology expertise.

Hira A, Yabe H, Yoshida K, et al.
Variant ALDH2 is associated with accelerated progression of bone marrow failure in Japanese Fanconi anemia patients.
Blood. 2013; 122(18):3206-9 [PubMed] Free Access to Full Article Related Publications
Fanconi anemia (FA) is a severe hereditary disorder with defective DNA damage response and repair. It is characterized by phenotypes including progressive bone marrow failure (BMF), developmental abnormalities, and increased occurrence of leukemia and cancer. Recent studies in mice have suggested that the FA proteins might counteract aldehyde-induced genotoxicity in hematopoietic stem cells. Nearly half of the Japanese population carries a dominant-negative allele (rs671) of the aldehyde-catalyzing enzyme ALDH2 (acetaldehyde dehydrogenase 2), providing an opportunity to test this hypothesis in humans. We examined 64 Japanese FA patients, and found that the ALDH2 variant is associated with accelerated progression of BMF, while birth weight or the number of physical abnormalities was not affected. Moreover, malformations at some specific anatomic locations were observed more frequently in ALDH2-deficient patients. Our current data indicate that the level of ALDH2 activity impacts pathogenesis in FA, suggesting the possibility of a novel therapeutic approach.

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