A susceptibility locus for epidermodysplasia verruciformis, an abnormal predisposition to infection with the oncogenic human papillomavirus type 5, maps to chromosome 17qter in a region containing a psoriasis locus.

Epidermodysplasia verruciformis (EV) is a rare genodermatosis characterized by an abnormal susceptibility to infection with a specific group of related human papillomavirus (HPV) genotypes, including the oncogenic HPV5 associated with the skin carcinomas developing in about half of EV patients. EV is usually considered as an autosomal recessive condition. Taking EV as a model to identify a locus underlying the susceptibility to HPV infections, we performed a genome-wide search for linkage with 255 microsatellite genetic markers in three consanguineous EV families comprising six patients, using the homozygosity mapping approach. Homozygosity restricted to affected individuals was observed for a marker of chromosome 17q (D17S784) in two families and a marker about 17 centiMorgan (cM) distal (D17S1807) in the third family. Ten additional microsatellite markers spanning 29 cM in this region were analyzed. Two-point lod score values greater than 3 were obtained for four markers and multipoint linkage analysis yielded a maximum lod score of 10.17 between markers D17S939 and D17S802. Recombination events observed in two families allowed a candidate region for the EV susceptibility locus to be mapped to the 1 cM region defined by these two markers. The EV locus (named EV1) is included in the 17qter region recently found to contain a dominant locus for the susceptibility to familial psoriasis. It has been shown that patients suffering from psoriasis are likely to constitute the reservoir of HPV5. It is thus tempting to speculate that distinct defects affecting the same gene may be involved in the two skin conditions.