MMP-9 gene polymorphisms (rs3918242, rs3918254 and rs4810482) and the risk of psoriasis vulgaris: No evidence for associations in a Chinese Han population

Several previous studies including one of them co-authored by our group have revealed that serum and psoriatic plaque expression of matrix metalloproteinase-9 (MMP-9) was significantly upregulated in psoriasis. The aim of this study was to investigate the association of three single nucleotide polymorphisms (SNPs) and haplotypes of MMP-9 (rs3918242, rs3918254 and rs4810482) with psoriasis vulgaris in a Chinese Han population. The serum levels of MMP-9 in 245 psoriasis vulgaris cases and 256 healthy controls were assessed using ELSA kits, and the three SNPs were genotyped using polymerase chain reaction-ligation detection reaction (PCR-LDR) method. Four haplotypes based on the three SNPs were also analyzed. Our study showed that the serum MMP-9 levels in patients with psoriasis vulgaris were significantly higher than that in controls (P < 0.05). However, the three SNPs were not significantly associated with psoriasis vulgaris susceptibility (all P > 0.05). Similar results were found in further subgroup analysis based on gender, age of onset, family history, and serum MMP-9 levels, except that a protective effect of psoriasis vulgaris was detected among female subjects with the CT genotype of rs3918254 (OR = 0.47, 95% CI = 0.23-0.96, P = 0.038), but this association did not survive after Bonferroni correction (Padj = 0.076). The haplotype analysis also failed to show any association with psoriasis vulgaris. We found no evidence for the association between the MMP-9 polymorphisms and psoriasis vulgaris susceptibility in a Chinese Han population.