Genetics of generalized vitiligo clarified
MedWire News: Results from a genomewide association study identify variants associated with generalized vitiligo at various loci previously associated with other autoimmune disorders.
In addition, a major allele association with vitiligo was seen for two single nucleotide polymorphisms (SNPs) in the tyrosinase gene (TYR) – rs1393350 and rs1126809 – the minor alleles of which have been linked to increased susceptibility for malignant melanoma.
Writing in the New England Journal of Medicine, the researchers report the results from a genomewide association study carried out to identify susceptibility loci for generalized vitiligo. They genotyped a total of 579,146 SNPs in 1514 patients of European-derived White (CEU) ancestry and compared them with publicly available genotypes from 2813 CEU individuals without vitiligo.
Richard Spritz (University of Colorado, Aurora, USA) and colleagues then tested 50 SNPs with the strongest initial associations in two replication sets comprising CEU individuals with and without vitiligo.
The team identified a total of 10 independent susceptibility loci for generalized vitiligo. Two were in the MHC region and the others were located in or near the genes RERE, PTPN22, LPP, IL2RA, TYR, GZMB, UBASH3A, and C1QTNF6.
The majority of these genes are associated with genetic susceptibility to other autoimmune disorders, some of which are linked to generalized vitiligo.
In contrast, TYR is not associated with the immune system, but produces an enzyme of the melanocyte that is involved in melanin biosynthesis.
The two TYR SNPs with the strongest association with generalized vitiligo associated with the major alleles were rs1393350 and rs1126809. Notably, the minor alleles of these SNPs have previously been linked to increased susceptibility to malignant melanoma, suggested a “mutually exclusive relationship between susceptibility to vitiligo and susceptibility to melanoma,” say the authors.
Spritz and co-authors conclude: “Although the implicated loci that we have described here together account for only approximately 7.4% of the total genetic risk for generalized vitiligo, they provide insights into disease pathogenesis and implicate potential targets for therapeutic intervention.”
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By Helen Albert