The association of GPIbα instrumented by cis‐pQTL meditated by platelet count with JIA could not be assessed because the causal variant of interest was not available for the outcome (Supplementary Table 8, available on the Arthritis & Rheumatology website at http://onlinelibrary.wiley.com/doi/10.1002/art.41561/abstract). Here, GP1BA is linked to juvenile idiopathic arthritis.