Leidenz FAB, Bittencourt FV, Braga WG, de Sá Araújo EM, Gomes CC, de Fatima Bernardes V, Friedman E, De Marco L. Familial Melanoma Phenotype With Xeroderma Pigmentosum Group C (XP-C) Genotype - The Putative Role of MC1R Polymorphism as Modifier.
Dermatol Pract Concept 2024;
14:dpc.1401a50. [PMID:
38364385 PMCID:
PMC10868875 DOI:
10.5826/dpc.1401a50]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/27/2023] [Indexed: 02/18/2024] Open
Abstract
INTRODUCTION
Xeroderma pigmentosum (XP), a rare inherited condition, hallmarked by extreme sensitivity to sun exposure resulting in multiple skin cancers and non-malignant skin alterations is attributed to homozygous inactivating pathogenic variants (PVs) in DNA repair genes, predominantly the XPC gene.
OBJECTIVES
Report a unique phenotypic expression of mutant XPC allele that may be compatible with a putative modifier role for MC1R polymorphism.
METHODS
A family of 13 siblings, seven of whom were diagnosed with at least one cutaneous melanoma (N = 53) and non-melanoma skin cancers (N = 9) was studied. Of seven melanoma-affected cases, five consented for genetic analysis. CDKN2A revealed no PV in any case and subsequent whole-exome sequencing (WES) identified a rare homozygous missense PV (c.919C>T; p.Arg307Trp) in exon 8 of the XPC gene in all affected individuals. Notably, XPC PV carriers who co-harbored the p.I155T MC1R variant (N = 3) exhibited larger number of tumors, deeper Breslow indexes, higher rates of invasive melanomas and earlier age at diagnosis compared with non MC1R variant carriers (N = 2).
CONCLUSIONS
Familial malignant melanoma phenotype may, in fact, be an unusual clinical presentation of XPC, and MC1R may be a genetic modifier of penetrance and phenotype of mutant XPC alleles.
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