Familial melanoma, pancreatic cancer and germline CDKN2A mutations

Germline CDKN2A mutations have been observed in approximately 20 percent of familial melanoma kindreds from North America, Europe and Australasia. There is also an increased risk of pancreatic cancer in a subset of families with mutations, however, the precise relationship between the CDKN2A gene and pancreatic cancer remains unknown. The relationships between familial melanoma, pancreatic cancer and germline CDKN2A mutations were examined using published data. There were 67 different CDKN2A mutations in 189 melanoma-prone families. Forty-two families (18 mutations) had pancreatic cancer reported. For families without reported pancreatic cancer, the most common types of mutations were missense (56%), frameshift (12%), and deletions (12%). For families with pancreatic cancer, missense (56%), splicing (17%), and frameshift (11%) mutations were most common. Seventy percent of the mutations were observed only once, while the remainder recurred in different families. Comparison of 147 melanoma-prone families without pancreatic cancer to the 42 families that had pancreatic cancer reported showed no significant differences in the types or locations of mutations. However, there was a significant difference (p=0.002) in the distribution of families across the four ankyrin repeats. This finding primarily resulted from the six most frequent mutations where the distribution of pancreatic cancer varied significantly (p=0.02) from at least 30% in c.301G>T (p.G101W), c.225_243del19 (p.P75fs), c.337_338insGTC (p.R112_L113insR), and c.377T>A (p.V126D) families to less than 10% in c.71G>C (p.R24P) and c.159G>C (p.M53I) families. Further research utilizing individual-specific data will be required to determine whether these patterns represent etiologic differences or incomplete reporting of cancer and mutation data.