Dataset Information

Inactivating Mutations in GT198 in Familial and Early-Onset Breast and Ovarian Cancers.

ABSTRACT: The human GT198 gene (gene symbol PSMC3IP) is located at chromosome 17q21, 470 kb proximal to BRCA1, a locus previously linked to breast and ovarian cancer predisposition. Its protein product (also known as TBPIP and Hop2) has been shown to regulate steroid hormone receptor-mediated gene activation and to stimulate homologous recombination in DNA repair. Here, we screened germline mutations in GT198 in familial and early-onset breast and ovarian cancer patients. We have identified 8 germline variants in a total of 212 index patients including reoccurring nonsense mutation c.310C>T (p.Q104X) and 5' UTR mutation c.-37A>T, each found in 2 unrelated families. Most identified index patients from cancer families had early onsets with a median age of 35 years. c.310C>T was absent in a total of 564 control individuals analyzed. GT198 gene amplification with an imbalanced mutant copy gain was identified in the blood DNA of one of the patients carrying c.310C>T. When tested, this truncating mutation abolished DNA damage-induced Rad51 foci formation. In addition, we have identified 15 somatic mutations in 2 tumors from 1 patient carrying germline mutation c.-37A>T. The presence of a somatic mutation on the wild-type allele showed that GT198 was biallelically mutated in the tumor. The somatic mutations identified near a splicing junction site caused defective alternative splicing and truncated the open reading frame. Therefore, distinct mutations may cause a similar consequence by truncating the full-length protein and inducing a loss of the wild type. Our study provides the first evidence of the presence of inactivating mutations in GT198 in familial and early-onset breast and ovarian cancer patients. Mutations in GT198, a gene regulating DNA repair, potentially contribute to an increased risk in familial breast and ovarian cancers.

SUBMITTER: Peng M

PROVIDER: S-EPMC3743154 | biostudies-literature | 2013 Jan

REPOSITORIES: biostudies-literature

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Inactivating Mutations in GT198 in Familial and Early-Onset Breast and Ovarian Cancers.

Peng Min M Bakker Janine L JL Dicioccio Richard A RA Gille Johan J P JJ Zhao Hua H Odunsi Kunle K Sucheston Lara L Jaafar Lahcen L Mivechi Nahid F NF Waisfisz Quinten Q Ko Lan L

Genes & cancer 20130101 1-2

The human GT198 gene (gene symbol PSMC3IP) is located at chromosome 17q21, 470 kb proximal to BRCA1, a locus previously linked to breast and ovarian cancer predisposition. Its protein product (also known as TBPIP and Hop2) has been shown to regulate steroid hormone receptor-mediated gene activation and to stimulate homologous recombination in DNA repair. Here, we screened germline mutations in GT198 in familial and early-onset breast and ovarian cancer patients. We have identified 8 germline var ...[more]

PMID: 23946868

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Project description:BackgroundThe aim of this study was to identify BRCA1 and BRCA2 mutations in the Estonian population. We analyzed genetic data and questionnaire from 64 early-onset (< 45 y) breast cancer patients, 47 familial cases (patients with breast or ovarian cancer and a case of these cancers in the family), and 33 predictive cases (patients without breast or ovarian cancer, with a family history of such diseases) from Estonia for mutations in the BRCA1 gene. A sub-set of familial cases and predictive cases were also analyzed for mutations in the BRCA2 gene.MethodsFor mutation detection, we used the Polymerase Chain Reaction-Single Stranded Conformation Polymorphism Heteroduplex Analysis (PCR-SSCP-HD), followed by direct DNA sequencing.ResultsWe identified three clinically important mutations in the BRCA1 gene, including seven occurrences of the c.5382insC mutation, three of c.4154delA, and one instance of c.3881_3882delGA. We also detected six polymorphisms: c.2430T>C, c.3232A>G, c.4158A>G, c.4427T>C, c.4956A>G, and c.5002T>C. Four sequence alterations were detected in introns: c.560+64delT, c.560+ [36-38delCTT, 52-63del12], c.666-58delT, and c.5396+60insGTATTCCACTCC. In the BRCA2 gene, two clinically important mutations were found: c.9610C>T and c.6631delTTAAATG. Additionally, two alterations (c.7049G>T and c.7069+80delTTAG) with unknown clinical significance were detected.ConclusionsIn our dataset, the overall frequency of clinically important BRCA1 mutations in early-onset patients, familial cases, and predictive testing was 7.6% (144 cases, 11 mutation carriers). Pathogenic mutations were identified in 4 of the 64 early-onset breast cancer cases (6.3%). In familial cases, clinically important mutations in the BRCA1 gene were found in 6 of the 47 individuals analyzed (12.8%). In predictive cases, 1 clinically important mutation was detected in 33 individuals studied (3%). The occurrence of clinically important mutations in BRCA2 in familial cases of breast cancer was 2 of the 16 individuals analyzed (12.5%).

Project description:ImportanceGermline mutations in established moderately or highly penetrant risk genes for breast cancer (BC) and/or ovarian cancer (OC), including BRCA1 and BRCA2, explain fewer than half of all familial BC and/or OC cases. Based on the genotyping of 2 loss-of-function (LoF) variants c.5101C>T (p.GIn1701Ter [rs147021911]) and c.5791C>T (p.Arg1931Ter [rs144567652]), the FANCM gene has been suggested as a novel BC predisposition gene, while the analysis of the entire coding region of the FANCM gene in familial index cases and geographically matched controls is pending.ObjectivesTo assess the mutational spectrum within the FANCM gene, and to determine a potential association of LoF germline mutations within the FANCM gene with BC and/or OC risk.Design, setting, and participantsFor the purpose of identification and characterization of novel BC and/or OC predisposition genes, a total of 2047 well-characterized familial BC index cases, 628 OC cases, and 2187 geographically matched controls were screened for LoF mutations within the FANCM gene by next-generation sequencing. All patients previously tested negative for pathogenic BRCA1 and BRCA2 mutations. All data collection occurred between June 1, 2013, and April 30, 2016. Data analysis was performed from May 1, 2016, to July 1, 2016.Main outcomes and measuresFANCM LoF mutation frequencies in patients with BC and/or OC were compared with the FANCM LoF mutation frequencies in geographically matched controls by univariate logistic regression. Positive associations were stratified by age at onset and cancer family history.ResultsIn this case-control study, 2047 well-characterized familial female BC index cases, 628 OC cases, and 2187 geographically matched controls were screened for truncating FANCM alterations. Heterozygous LoF mutations within the FANCM gene were significantly associated with familial BC risk, with an overall odds ratio (OR) of 2.05 (95% CI, 0.94-4.54; P = .049) and a mutation frequency of 1.03% in index cases. In familial patients whose BC onset was before age 51 years, an elevated OR of 2.44 (95% CI, 1.08-5.59; P = .02) was observed. A more pronounced association was identified for patients with a triple-negative BC tumor phenotype (OR, 3.75; 95% CI, 1.00-12.85; P = .02). No significant association was detected for unselected OC cases (OR, 1.74; 95% CI, 0.57-5.08; P = .27).Conclusions and relevanceBased on the significant associations of heterozygous LoF mutations with early-onset or triple-negative BC, FANCM should be included in diagnostic gene panel testing for individual risk assessment. Larger studies are required to determine age-dependent disease risks for BC and to assess a potential role of FANCM mutations in OC pathogenesis.

Dataset Information

Inactivating Mutations in GT198 in Familial and Early-Onset Breast and Ovarian Cancers.

Publications

Inactivating Mutations in GT198 in Familial and Early-Onset Breast and Ovarian Cancers.

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