Abstract
Psoriasis is a common inflammatory skin disease with genetic components of both immune system and the epidermis. PSOR1 locus (6q21) has been strongly associated with psoriasis; however, it is difficult to identify additional independent association due to strong linkage disequilibrium in the MHC region. We performed stepwise regression analyses of more than 3,000 SNPs in the MHC region genotyped using Human 610-Quad (Illumina) in 1,139 cases with psoriasis and 1,132 controls of Han Chinese population to search for additional independent association. With four regression models obtained, two SNPs rs9468925 in HLA-C/HLA-B and rs2858881 in HLA-DQA2 were repeatedly selected in all models, suggesting that multiple loci outside PSOR1 locus were associated with psoriasis. More importantly we find that rs9468925 in HLA-C/HLA-B is associated with both psoriasis and vitiligo, providing first important evidence that two major skin diseases share a common genetic locus in the MHC, and a basis for elucidating the molecular mechanism of skin disorders.
Highlights
Psoriasis [MIM#177900] is a T cell-mediated inflammatory skin disease, characterized by epidermal hyperproliferation and dermal inflammation [1,2]
We have examined the association of SNPs in the major histocompatibility complex (MHC) region with psoriasis using multiple regression models
SNP rs9468925 in HLA-C/HLA-B consistently appears in all four regression models, indicating that an independent HLA locus is associated with psoriasis
Summary
Psoriasis [MIM#177900] is a T cell-mediated inflammatory skin disease, characterized by epidermal hyperproliferation and dermal inflammation [1,2]. It affects 2–3% of people in the European ancestry population [1], while 0.123% of individuals in the Asian population [3]. The PSORS1 locus is likely to account for about 30% to 50% of the heritability of the disease [6,7,8], and has been believed to be the major genetic determinant of psoriasis [9]
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