Germline variants in CDKN2A wild-type melanoma prone families

Germline pathogenic variants in CDKN2A are well established as an underlying cause of familial malignant melanoma. While pathogenic variants in other genes have also been linked to melanoma, most familial cases remain unexplained. We assessed pathogenic germline variants in 360 cancer-related genes in 56 Norwegian melanoma-prone families. The index cases were selected based on familial history of melanoma and/or multiple primary melanomas, along with previous negative tests for pathogenic CDKN2A variants. We found 6 out of 56 index individuals to carry germline pathogenic or likely pathogenic variants in BRCA2, MRE11, ATM, MSH2, CHEK2, and AR. One family member with melanoma (not index case) carried a pathogenic variant in MAP3K6. In addition, we found a high fraction of variants previously considered benign and/or as variants of uncertain significance in xeroderma pigmentosum-related genes. In particular, XPC^L48F was found in 8 indexes; thus, the allele fraction (0.07) was significantly higher than in comparable healthy populations (0.02-0.03; P-values from 0.007 to 0.014). In conclusion, we found that several melanoma-prone families have pathogenic variants in genes not usually linked to melanoma.