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

Abstract

Germline mutations in the p16 (CDKN2A) tumour suppressor gene have been linked to inherited predisposition to malignant melanoma (MM). Variable frequencies of p16 germline mutations were reported in different collections of melanoma 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 coding region of the p16 gene, including exons 1, 2 and 3, flanking exon/intron 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 G122V, a novel missense mutation. Thus, the frequency of mutations identified in this collection of Israeli families was 7%. Functional analysis indicated that the novel G122V variant retained some capacity to interact with cyclin 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 G122V substitution on the 3-dimensional structure of the p16 protein.

Search for germline alterations in CDKN2A/ARF and CDK4 of 42 Jewish melanoma families with or without neural system tumours

“…The only sequence variation identified in nine DNA samples was G to A transition at position 442 leading to a missense mutation at codon 148 (Ala148Thr). The Ala148Thr missense mutation is considered as a polymorphism based on several observations: it has been previously reported in individuals from the general, average risk, population in ethnically diverse groups: 8% of the Jewish population (Yakobson et al, 2000), 4% of the population in Utah (Kamb et al, 1994) and 5% in the UK population (Bertram et al, 2002). Furthermore, this missense mutation did not segregate with the phenotype in familial melanoma (Hussussian et al, 1994;Harland et al, 1997), and is situated outside the critical four ankyrin repeat domains of p16, and thus does not appear to have any effect in vitro on binding to CDK4 (Ranade et al, 1995;Lilischkis et al, 1996;Harland et al, 1997).…”

Genetics of melanoma predisposition

“…No Ashkenazi family has been reported to have a mutation in either CDKN2A or CDK4 (Yakobson et al, 2000). Considering the common founder mutations identified in this population in other cancer predisposition genes (e.g.…”

A single Mediterranean, possibly Jewish, origin for the Val59Gly CDKN2A mutation in four melanoma-prone families

“…PCR reactions using genomic DNA of individuals from all four melanoma families were performed as described. 20 PCR products were separated on 6%…”

“…20 Genomic DNA was extracted from whole-blood samples and DNA fragments containing p16 gene exon 1, exon 2 (fragments 2A, 2B and 2C) and exon 3, with respective intron/exon junctions and the untranslated 3 0 portion were amplified using 33 P labeled nucleotides, and electrophoretically separated for SSCP analysis. Variant SSCP bands were purified, reamplified and sequenced.…”