Novel Variant and a Possible New Founder Effect for Xeroderma Pigmentosum Variant Type in Southeast Brazil: Case Report.

INTRODUCTION: Xeroderma pigmentosum (XP) is a group of genodermatoses with autosomal recessive inheritance, comprising 9 subtypes designated A to J plus a variant (V) type, clinically characterized by increased photosensitivity, with specific subtypes more prone to ocular disease and progressive neurodegeneration. CASE PRESENTATION: Three patients with the XP-V variant, a pair of sisters and an unrelated individual, presented with a novel homozygous c.1245-1G>A intronic splice site variant in the POLH gene classified as likely pathogenic. They exhibited numerous freckles and hypo- and hyperpigmented lesions that evolved into basal cell and squamous cell carcinomas, as well as thin malignant melanocytic lesions, photophobia, conjunctival telangiectasis, ectropion, and pterygia, without neurological symptoms. CONCLUSION: The possibility of dealing with a new founder effect for this specific variant in the State of Minas Gerais, in the Southeast region of Brazil, is suggested.