No Apparent Contribution of MICA to Psoriasis Risk
MICA variants demonstrated nominally significant associations with PsV, PsA, and PsC risk (the lowest p value, pomnibus = 2.2 × 10−180, was at MICA amino acid position 298 for PsV-affected versus control individuals; Table S2). However, after we conditioned on HLA-C and HLA-B, no MICA variants showed independent association signals (p > 5.0 × 10−8 for any of the four tested phenotype comparisons). Previous studies have suggested independent effects of several MICA variants, such as MICA∗016, MICA∗008:01, and MICA amino acid position 129, on PsV or its subphenotypes,19,20 but our study did not observe apparent associations of these variants when we conditioned on HLA-C∗06:02 or HLA-B amino acid position 67 (p > 0.017). We note that no significant association was observed in the MICA variants in direct comparison between PsA subjects and PsC subjects (p > 5.0 × 10−8). Therefore, our study could not identify an independent contribution of MICA on risk of psoriasis and its clinical subtypes.