Retention of the CDKN2A locus and low frequency of point mutations in primary and metastatic cutaneous malignant melanoma.

CDKN2A has been found mutated in melanoma families which show linkage to chromosome 9p21. In contrast, a low mutation rate has been found in melanomas, suggesting that CDKN2A might not be the first target for mutation in the development of this type of tumour. To elucidate the role of the CDKN2A gene and its alternative transcript p19ARF in the development of cutaneous malignant melanoma (CMM) we have analyzed 48 primary and metastasic CMM tumours for mutations and for loss of heterozygosity (LOH). Only one point mutation was detected (2%), while hemizygous deletions were identified in 20% of these tumours. Retention of the CDKN2A locus was found in 10 (47%) tumours with deletions at one or both sides of CDKN2A, suggesting that loss of this gene is not involved in CMM-tumour initiation and that another tumour-suppressor gene involved in melanoma is located at 9p21.