More recent RCTs, such as the FEATHER [61], PERL (serum urate lowering with allopurinol and kidney function in type 1 diabetes) [66], and CKD-FIX (Controlled trial of slowing of Kidney Disease progression From the Inhibition of Xanthine oxidase) [67] trials, did not show clinically meaningful benefits with SUA reduction using allopurinol and febuxostat in patients with CKD up to stage 4 without gout. This evidence concerns the gene XDH and gout.