The BRCA2 c.9004G > A (E2003K) variant is likely pathogenic and recurs in breast and/or ovarian cancer families of French Canadian descent

Service de Médecine Génique, Département de Médecine, Centre Hospitalier de l'Université de Montréal, Montreal, Canada.
Breast Cancer Research and Treatment (Impact Factor: 4.2). 09/2011; 131(1):333-40. DOI: 10.1007/s10549-011-1796-4
Source: PubMed

ABSTRACT Specific BRCA1 and BRCA2 mutations recur in French Canadian breast and/or ovarian cancer families because of common ancestors, facilitating carrier detection in this population. We recently reported a BRCA2 c.9004G>A variant of unknown clinical significance in two French Canadian breast cancer families. It confers a E3002K alteration in the conserved C-terminus domain of BRCA2, and has been reported in non-French Canadian cancer families. Seven variant positive French Canadian families have since been identified by mutation screening of referrals to hereditary cancer clinics. In this article, we describe the cancer phenotypes of these families and further assess the contribution of this variant in the French Canadian population. We screened index breast cancer cases from 58 cancer families with at least three confirmed cases of breast and/or ovarian cancer and 960 breast cancer cases (48 years mean age) not selected for family history of cancer that were previously found not to carry the most common BRCA1 and BRCA2 mutations reported in this population. The index variant-positive cases from each family had breast cancer between the ages of 35-55 years (43 years mean age); and reported close relatives with breast cancer diagnoses between the ages of 28-84 years (57 years mean age). Three families had ovarian or peritoneal cancers. BRCA2-associated cancers, such as bladder, esophagus, pancreas, prostate, and thyroid cancers also occurred in these families. One c.9004G>A carrier also harbored the PALB2 c.2323C>T (Q775X) mutation found to recur in French Canadian breast cancer cases. No new BRCA2 variant carriers were identified in mutation screens. The absence of BRCA2 c.9004G>A carriers in the breast cancer cases not selected for family history contrasts with familial cases, supporting a pathogenic status for this variant and addition to the existing common BRCA1 and BRCA2 mutation-screening panel for French Canadian breast and/or ovarian cancer families.

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    ABSTRACT: Background The PALB2 c.2323C>T [p.Q775X] mutation has been reported in at least three breast cancer families and breast cancer cases of French Canadian descent and this has been attributed to common ancestors. The number of mutation-positive cases reported varied based on criteria of ascertainment of index cases tested. Although inherited PALB2 mutations are associated with increased risks of developing breast cancer, risk to ovarian cancer has not been fully explored in this demographically unique population. Methods We screened the PALB2 p.Q775X variant in 71 families with at least three cases of breast cancer (n=48) or breast and ovarian cancers (n=23) that have previously been found negative for at least the most common BRCA1 and BRCA2 mutations reported in the French Canadian population and in 491 women of French Canadian descent who had invasive ovarian cancer and/or low malignant potential tumors of the major histopathological subtypes. Results We identified a PALB2 p.Q775X carrier in a breast cancer family, who had invasive ductal breast carcinomas at 39 and 42 years of age. We also identified a PALB2 p.Q775X carrier who had papillary serous ovarian cystadenocarcinoma at age 58 among the 238 serous subtype ovarian cancer cases investigated, who also had breast cancer at age 52. Conclusion Our findings, taken together with previous reports, support adding PALB2 c.2323C>T p.Q775X to the list of cancer susceptibility genes for which founder mutations have been identified in the French Canadian population.
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