Deep intronic founder mutations identified in the / gene are potential therapeutic targets for a high-frequency form of xeroderma pigmentosum.

Xeroderma pigmentosum (XP) is a genodermatosis defined by cutaneous photosensitivity with an increased risk of skin tumors because of DNA repair deficiency. The worldwide prevalence of XP is ~1 to 4 in million, with higher incidence in some countries and regions including Japan (1 in 22,000) and North Africa due to founder mutations and a high degree of consanguinity. Among XP, the complementation group F (XP-F), is a rare form (1% of worldwide XP); however, this is underdiagnosed, because the / gene is essential for fetal development and most of previously reported / pathogenic variants are hypomorphs causing relatively mild phenotypes.