Genetic variations in IL6 and IL12B decreasing the risk for psoriasis

Psoriasis is a chronic inflammatory skin disorder. Recent studies associated a number of genetic variants to this immune-mediated pathology.

This study aims to assess whether the association between the non-susceptibility allelic variants of IL12B single-nucleotide polymorphism (SNPs) rs3212227 and rs6887695, IL23R SNPs rs11209026 and rs7530511, IL6 SNP rs1800795 and HLA-Cw6 could be correlated with decreased risk for psoriasis.

We genotyped 67 psoriasis patients and 69 healthy subjects for polymorphisms of IL12B rs3212227 and rs6887695, IL23R rs11209026 and rs7530511, IL6 rs1800795 and for the presence of HLA-Cw6. The patients and controls were recruited from Dermatology Department, part of "Tor Vergata" Clinic, Rome. Demographic data of the control group matched those of psoriasis patients, with a female:male ratio of 2.55 and mean age of 45.5±12.2 years for patients and 44.8±11.7 years for controls.

The following genotypes were less frequent in patients: IL12B SNP rs6887695 CC (OR, 0.179; CI95% 0.046-0.699; p=0.01), IL6 SNP rs1800795 CG (OR, 0.367; CI95% 0.179-0.753; p=0.006) and IL6 SNP rs1800795 CC (OR, 0.069; CI95% 0.008-0.586; p=0.01). Also the HLA-Cw6 allele was rarely found in controls (OR, 0.459; CI95% 0.230-0.916; p=0.02). The multivariate analysis showed that the existence of at least one C allele in both IL12B SNP rs6887695 and IL6 SNP rs1800795 or the absence of HLA-Cw6 allele and at least one C allele in IL12B SNP rs6887695 or IL6 SNP rs1800795 is associated with a lower risk of psoriasis (OR, 0.185; CI95% 0.037-0.929; p=0.04). The presence of at least one C allele in both IL12B SNP rs6887695 and IL6 SNP rs1800795 and the absence of HLA-Cw6 allele decreased even further the risk of psoriasis (OR, 0.038; CI95% 0.006-0.244; p=0.001).

We report carriers of variations in the IL6, IL12B and absence of HLA-Cw6 as having decreased risk for psoriasis.