Association Testing of KIR3DS1 with Psoriasis.

The combination of KIR3DS1 and HLA-B Bw4-80I has a large effect on psoriasis susceptibility, whereas KIR3DS1 without Bw4-80I, and Bw4-80I without KIR3DS1, have little effect. Thus, the compound genotype KIR3DS1+Bw4-80I drives the individual associations of KIR3DS1 and Bw4-80I with psoriasis (bottom two rows). aFrequencies of individuals positive for each allele. bp-values were tested by a two-sided Fisher's exact test (dominant model). cLogistic regression based conditional association testing of “KIR3DS1+Bw4-80I” on HLA-C*06:02 remained significant at p = 9.99×10−5, OR = 3.16 [1.77–5.63], whereas conditional testing of “Bw4-80I without KIR3DS1” on HLA-C*06:02 resulted in a non-significant p-value of 0.579, OR = 1.14 [0.72–1.80]. Thus, Bw4-80I does not have an independent effect on psoriasis susceptibility in the absence of KIR3DS1.