BRCA1, BRCA2, PALB2, and CDKN2A Mutations in Familial Pancreatic Cancer (FPC): A PACGENE Study

PURPOSE: Familial Pancreatic Cancer (FPC) kindreds contain at least two affected first-degree relatives (FDR). Comprehensive data are needed to assist clinical risk assessment and genetic testing. METHODS: Germline DNA samples from 727 unrelated probands with positive family history (521 met criteria for FPC) were CLIA-tested for mutations in BRCA1 and BRCA2 (including analysis of deletions and rearrangements), PALB2, and CDKN2A. We compared prevalence of deleterious mutations between FPC probands and non-FPC probands (kindreds containing at least two affected biologic relatives, but not FDR). We also examined the impact of family history of breast and ovarian cancer and melanoma. RESULTS: Prevalence of deleterious mutations (excluding variants of unknown significance) among FPC probands was: BRCA1, 1.2%; BRCA2, 3.7%; PALB2, 0.6%; CDKN2A, 2.5%. Four novel deleterious mutations were detected. FPC probands carry more mutations in the four genes (8.0%) than non-FPC probands (3.5%) (odds ratio=2.40, 95% CI=(1.06, 5.44), p=0.03). The probability of testing positive for deleterious mutations in any of the four genes ranges up to 10.4%, depending upon family history of cancers. BRCA2 and CDKN2A account for the majority of mutations in FPC. CONCLUSION: Genetic testing of multiple relevant genes in probands with a positive family history is warranted, particularly for FPC.