Resequencing of the IL12B gene in psoriasis patients with the rs6887695/rs3212227 risk genotypes

► IL12B SNP rs6887695 was strongly associated with psoriasis. ► Sequencing of IL12B in psoriasis patients identified several known polymorphisms. ► None of the five additional SNPs was a risk factor for psoriasis. Recent genomic surveys have identified IL12B as susceptibility locus for psoriasis (Ps). Our aim was to replicate the association between IL12B SNPs and Ps. In addition, we sequenced the IL12B gene in several patients to identify new variants that could explain the disease-risk. A total of 304 Ps-patients and 422 healthy controls (all Caucasian Spanish) were genotyped for three IL12B polymorphisms. SNP rs6887695 (GG genotype) was significantly associated with Ps (p=0.002; OR=1.60, 95% CI=1.19–2.16). This genotype was also more frequent among patients with severe psoriasis (p=0.03). Sequencing of 30 patients with the risk genotype identified several IL12B reported SNPs. Allele and genotype frequencies for two putative functional variants (rs3213120 and rs3213119) did not differ between patients and controls. Our study confirmed rs6887695 as a risk factor for Ps. No other IL12B variants that could explain this association were found in our patients.