Variant of TYR and autoimmunity susceptibility loci in generalized vitiligo.

BACKGROUND: Generalized vitiligo is an autoimmune disease characterized by melanocyte loss, which results in patchy depigmentation of skin and hair, and is associated with an elevated risk of other autoimmune diseases. METHODS: To identify generalized vitiligo susceptibility loci, we conducted a genomewide association study. We genotyped 579,146 single-nucleotide polymorphisms (SNPs) in 1514 patients with generalized vitiligo who were of European-derived white (CEU) ancestry and compared the genotypes with publicly available control genotypes from 2813 CEU persons. We then tested 50 SNPs in two replication sets, one comprising 677 independent CEU patients and 1106 CEU controls and the other comprising 183 CEU simplex trios with generalized vitiligo and 332 CEU multiplex families. RESULTS: We detected significant associations between generalized vitiligo and SNPs at several loci previously associated with other autoimmune diseases. These included genes encoding major-histocompatibility-complex class I molecules (P=9.05x10(-23)) and class II molecules (P=4.50x10(-34)), PTPN22 (P=1.31x10(-7)), LPP (P=1.01x10(-11)), IL2RA (P=2.78x10(-9)), UBASH3A (P=1.26x10(-9)), and C1QTNF6 (P=2.21x10(-16)). We also detected associations between generalized vitiligo and SNPs in two additional immune-related loci, RERE (P=7.07x10(-15)) and GZMB (P=3.44x10(-8)), and in a locus containing TYR (P=1.60x10(-18)), encoding tyrosinase. CONCLUSIONS: We observed associations between generalized vitiligo and markers implicating multiple genes, some associated with other autoimmune diseases and one (TYR) that may mediate target-cell specificity and indicate a mutually exclusive relationship between susceptibility to vitiligo and susceptibility to melanoma.

Comprehensive analysis of oculocutaneous albinism among non-Hispanic caucasians shows that OCA1 is the most prevalent OCA type.

Oculocutaneous albinism (OCA) is a genetically heterogeneous group of disorders characterized by absent or reduced pigmentation of the skin, hair, and eyes. In humans, four genes have been associated with "classical" OCA and another 12 genes with syndromic forms of OCA. To assess the prevalence of different forms of OCA and different gene mutations among non-Hispanic Caucasian patients, we performed DNA sequence analysis of the four genes associated with "classical" OCA (TYR, OCA2, TYRP1, SLC45A2), the two principal genes associated with syndromic OCA (HPS1, HPS4), and a candidate OCA gene (SILV), in 121 unrelated, unselected non-Hispanic/Latino Caucasian patients carrying the clinical diagnosis of OCA. We identified apparent pathologic TYR gene mutations in 69% of patients, OCA2 mutations in 18%, SLC45A2 mutations in 6%, and no apparent pathological mutations in 7% of patients. We found no mutations of TYRP1, HPS1, HPS4, or SILV in any patients. Although we observed a diversity of mutations for each gene, a relatively small number of different mutant alleles account for a majority of the total. This study demonstrates that, contrary to long-held clinical lore, OCA1, not OCA2, is by far the most frequent cause of OCA among Caucasian patients.

A comprehensive genetic study of autosomal recessive ocular albinism in Caucasian patients.

PURPOSE: Autosomal recessive ocular albinism (AROA) is a group of genetic disorders in which reduced pigmentation of the eye is associated with decreased visual acuity, nystagmus, strabismus, and photophobia, although pigmentation of skin and hair is relatively normal. Previous studies have shown that AROA in some cases constitutes a clinically mild presentation of oculocutaneous albinism (OCA), due to mutations in either the TYR (OCA1) or OCA2 (P) genes. The purpose of this study was to characterize the relative prevalence of different genetic forms of AROA, and to characterize a sample repertoire of gene mutations in a large series of Caucasian patients with AROA. METHODS: Thirty-six unrelated Caucasian patients carrying the clinical diagnosis of AROA were studied by DNA sequence analysis of the four classic OCA genes: TYR, OCA2 (P), TYRP1, and SLC45A2 (MATP), as appropriate. In all patients with no apparent pathologic mutations in these genes, DNA sequence analysis was performed of a candidate OCA gene, SILV, and the two genes most often involved in Hermansky-Pudlak syndrome, HPS1 and HPS4, the most frequent syndromic form of OCA. RESULTS: TYR gene mutations were identified in 20 (56%) patients, OCA2 mutations in 3 (8%), mutations in both TYR and OCA2 in 2 (6%), and possible TYRP1 mutations in 2 (6%). In at least nine patients, no mutations were found in any of the genes studied. Almost all patients with OCA1-related AROA were compound heterozygous for severe OCA1 mutant alleles and the common R402Q variant. CONCLUSIONS: Most patients with AROA represent phenotypically mild variants of OCA, well over half of which is OCA1.