TNF and inflammatory bowel disease: When we compared the distribution of genotype frequencies of the six SNPs in IBD patients with PP and psoriatic patients without PP (Table 4), statistically significant differences in the distribution of genotypes emerged for HLA-Cw06 rs10484554 (p = 0.02), IL23R rs10789229 (p = 0.01), and TNF-α rs1799964 (p = 0.04).