Overlap with SLE or PM/DM and elevation of creatine phosphokinase (CPK) were common in anti-topo I + U1RNP group (P = 0.009 for SLE, P = 0.07 for CPK, P = 0.05 for PM/DM; Table 1). Here, PIK3C2A is linked to systemic lupus erythematosus.