Cutaneous malignant melanoma (CMM; MIM #155601) comprises about 1% of all cancer cases in European populations, but its mortality is over 2% because of the propensity of this tumour to metastasise. Surveillance of CMM-prone individuals and populations should decrease the morbidity and mortality associated with this disease.

In approximately 5–12% of all melanoma cases, there is a family history of the disease, defined as having one or more affected first degree relatives.¹ Germline mutations of CDKN2A, located on chromosome 9p21, cosegregate with affected cases in an estimated 20% of melanoma families worldwide (reviewed by Goldstein²). CDKN2A encodes two different tumour suppressor proteins: the CDK4/6 cell cycle inhibitor p16^INK4A from exons 1α, 2, and 3; and the MDM2 inhibitor p14^ARF from exons 1β, 2, and 3. The frequency of discovering a CDKN2A mutation within a family increases with the number of affected relatives, ranging from ∼15% in families with two affected members, to 20–40% in those with three, and 70% in those with four or more (unpublished data from Hogg’s laboratory; Kefford and Mann¹). In addition, mutations in the CDK4 gene^3,4 and polymorphisms in the MC1R gene⁵ have been implicated rarely in melanoma predisposition.

To date, mutations in the two major predisposition genes, CDKN2A and CDK4, account for melanoma susceptibility in less than half of all melanoma families,⁶ and the genetic bases of the disease in the remaining families have not been found. Gillanders et al recently provided strong evidence for another melanoma predisposition locus at chromosome 1p22.⁷ Current research in melanoma genetics is hindered by the allelic and locus heterogeneities, which render whole genome linkage analysis difficult. In addition, the sample sizes required to study the effects of weak or modifier alleles in a genetically heterogeneous …