Importantly, the most recent placebo-controlled trials, Controlled Trial of Slowing of Kidney Disease Progression from the Inhibition of Xanthine Oxidase (CKD-FIX) [26] and Preventing Early Renal Loss in Diabetes (PERL) [27] however, have failed to demonstrate better renal outcomes in the allopurinol group compared with placebo. The gene discussed is XDH; the disease is diabetes mellitus.