Two p16 (CDKN2A) germline mutations in 30 Israeli melanoma families

Germline mutations in the p16 (CDKN2A) tumour suppressor gene have been lin ked to inherited predisposition to malignant melanoma (MM). Variable freque ncies of p16 germline mutations were reported in different collections of m elanoma families but it can be as high as 50%. Here we describe the results of p16 mutation screening in 30 melanoma kindreds in Israel. The entire co ding region of the p16 gene, including exons 1, 2 and 3, flanking exon/intr on junctions, and a portion of the 3' untranslated (UTR) region of the gene were examined by single-stranded conformation polymorphism (SSCP) analysis and direct sequencing. Two p16 germline mutations were identified: G101W, which has been previously observed in a number of melanoma kindreds, and G1 22V, a novel missense mutation. Thus, the frequency of mutations identified in this collection of Israeli families was 7%. Functional analysis Indicat ed that the novel G122V variant retained some capacity to interact with cyc lin dependent kinases (CDKs) in vitro, yet it was significantly impaired in its ability to cause a G1 cell cycle arrest in human diploid fibroblasts. This partial loss of function is consistent with the predicted impact of G1 22V substitution on the 3-dimensional structure of the p16 protein.