Objective: To study of the HLA-DQA(1) alleles and environment interaction in type I psoriasis.
Methods: Using case-control study, 144 type I psoriatics and 273 healthy people were investigated. The HLA-DQA(1) alleles were examined by PCR-SSP.
Results: (1) HLA-DQA(1)*0104 and DQA(1)*0201 alleles were positively associated with type I psoriasis (P(c) < 0.002); HLA-DQA(1)*0501 allele was negatively associated with type I psoriasis (P(c) < 0.000 5). (2) The HLA-DQA(1)*0104 allele and moisture was interaction in type I psoriasis (P = 0.023 8, OR = 5.29). (3) There were no interactions between the HLA-DQA(1)*0201 allele and 10 environmental factors in type I psoriasis. (4) The HLA-DQA(1)*0501 allele, moisture (P = 0.002 4, OR = 7.50), eating fish and shrimp (P = 0.000 4, OR = 12.92), drugs (P = 0.043 3, OR = 9.43) or vaccination (P = 0.043 3, OR = 9.43) were interacted in type I psoriasis.
Conclusions: (1) HLA-DQA(1)*0104 and DQA(1)*0201 alleles might be the susceptible genes or it may have close linkage with the susceptible gene. HLA-DQA(1)*0501 allele had protective effect against the development of type I psoriasis. (2) The HLA-DQA(1)*0104 and DQA(1)*0501 alleles increased risk possibility of environmental factors in type I psoriasis.