Association of MIF promoter polymorphisms with psoriasis in a Han population in northeastern China

Macrophage migration inhibitory factor (MIF) is a pro-inflammatory cytokine that plays an important part in the pathogenesis of autoimmune diseases. A high level of MIF has been detected in plaques of psoriasis and the sera of patients with psoriasis. Polymorphisms associated with autoimmune and inflammatory diseases exist in the promoter region of MIF and alter its expression.

The aim of this study was to evaluate the potential relationship between functional polymorphisms of MIF and psoriasis in a Han population in northeastern China.

Two-hundred-and-forty psoriasis patients and a control group of 269 healthy volunteers were included in this study. We genotyped MIF-173G/C using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). MIF-794CATT(5-8) microsatellite polymorphism was genotyped by polyacrylamide gel electrophoresis (PAGE).

No significant difference in the distributions of alleles, genotypes and haplotypes was observed between patients and controls. When patients were divided into subtypes according to sex, family history and age of onset, distribution of the MIF-173C allele between male and female patients was significantly different (P=0.04). MIF-173C allelic distribution between late onset psoriasis patients and controls was also different (P=0.02), as well as late onset patients and early onset subjects (P=0.04).

These results suggested a preliminary association between the MIF-173C allele and male psoriasis and late onset psoriasis in the studied population. In addition, the distributions of the two polymorphisms in Asian populations were quite different from the other continental populations.