Genetic and Epidemiologic Evaluation of Dysplastic Nevi

Dysplastic Nevus Syndrome (DNS) has been defined as that trait characterized by the presence of at least one dysplastic melanocytic nevus. DNS was originally described in kindreds having multiple members with melanoma. Various types DNS have been described in other situations to include individuals with apparently sporadic cases, familial DNS without melanoma and individuals with apparently sporadic DNS with melanoma. These categories are based on historical information in general, and not on examination of family members. In all cases, the presence of dysplastic nevi appear to confer some increased risk of melanoma, which varies between the groups. Similarly cutaneous melanoma is thought to occur in several distinct populations‐random individuals without DNS, individuals with sporadic DNS, and those with familial DNS.Genetic analysis of DNS has been largely confined to the classically ascertained kindreds associated with melanoma. These studies have usually used diagnostic criteria based on pathology of clinically selected material, and that evidence suggests that DNS is inherited as an autosomal dominant trait in these families. Surveys of the general population have detected rates of dysplastic nevi of 5% 20%. In our Utah‐based studies, we have evaluated probands and family members from three groups. These included kindreds with multiple occurrences of melanoma, random individuals with at least one dysplastic nevus, and cases of melanoma with unknown family history. Controls were spouses of study subjects. We sought to determine the percentage of each group associated with dysplastic nevi and/or genetic DNS. The range of phenotype of patients with dysplastic nevi was large with some individuals having few nevi, none of which were clinically atypical, and others having greater than 100 nevi. The prevalence of dysplastic nevi in at least one of two biopsies in Utah population controls is presently Wtimated at 62%. Some probands with melanoma as well as some of their relatives had elevated numbers of nevi, suggesting that this predisposition to melanoma may be inherited.