Epigenetic mutations in CDKN2A in western Swedish families with hereditary malignant melanoma.
This study aimed to identify the molecular genetic variations associated with an increased risk of hereditary malignant melanoma (HMM) in the western Swedish population. In 68 families with increased hereditary susceptibility to malignant melanoma, we previously reported a low frequency of alterations in the CDKN2A gene, which is regarded as the major melanoma predisposition gene. Among these alterations, we identified a novel mutation in 3 families (Asp108Tyr). In the present study, we focused on the possible role of heritable epimutations as a cause of the silencing of the CDKN2A gene. We used two different technical approaches to detect changes in CpG methylation in the promoter region of the CDKN2A gene; methylation-specific PCR (MSP) analysis of bisulfite-converted DNA and methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA). From families who tested negative for germ-line CDKN2A mutations, 64 unrelated patients with hereditary melanoma were included in the study. We showed a consistent lack of hypermethylation in the promoter region of CDKN2A in patients with HMM in our western Swedish population. A putative germ-line methylation of the CDKN2A, if any, is therefore likely to be a rare event in hereditary melanoma. This study demonstrates that there are probably additional and as yet unknown genetic factors present in western Swedish HMM families.