CXCL6 and palmoplantar pustulosis: Third, although our Mendelian randomized method proved beneficial for determining causation, considering the inherent restrictions of MR investigations, it would be ideal for corroborating the previous findings by examining the relationship between blood levels of CCL19, CXCL6, IL-6, and the severity of PPP in a sizable cohort of PPP patients in the future.