Functional, Structural, and Genetic Evaluation of 20 CDKN2A Germ Line Mutations Identified in Melanoma-Prone Families or Patients

Germline Mutations of the CDKN2A gene are found in melanoma-prone families and individuals with multiple sporadic melanomas. The encoded protein, p16(INK4A), comprises four ankyrin-type repeats, and the mutations, most of which are missense and occur throughout the entire coding region, call disrupt the conformation of these structural motifs as well as the association of p16(INK4a) its physiological targets, the cyclin-dependent kinases (CDKs) CDK4 and CDK6. Assessing pathogenicity of nonsynonymous Mutations is critical to evaluate melanoma risk in carriers. In the current study we investigate 20 CDKN2A germline mutations effects oil p16INK4A structure and function have not been previously documented (Thr18_Ala19dup, Gly23Asp, Arg24Gln, Gly35Ala, Gly35Val, Ala57Val, Ala60Val, Ala60Arg, Leu65dup, Gly67Arg, Gly67_Asn71del, Glu69Gly, Asp74Tyr, Thr77Pro, Arg80Pro, Pro81Thr, Arg87Trp, Leu97Arg, Arg99Pro, and [Leu 113Leu;Pro114Ser]). By considering genetic information, the predicted impact of each variant oil the protein structure, its ability to interact with CDK4 and impede cell proliferation in experimental settings, We conclude that 18 of the 20 CDKN2A variants can be classed Lis loss of function mutations, whereas the results for two remain ambiguous. Discriminating between mutant and neutral variants of p16(INK4A) not only adds to our understanding of the functionally critical residues in the protein but provides information that call be used for melanoma risk prediction. Hum Mutat 30, 564-574, 2009. (C) 2009 Wiley-Liss, Inc.