SLC7A11 and cystinuria: In genetic disorders, cystinuria is caused by mutations in SLC7A9/SLC3A1, leading to dysfunction of the cystine/glutamate antiporter (SLC7A11/xCT) and defective renal tubular cystine reabsorption, compounded by insufficient compensatory activity of the NADPH-dependent disulfide reductase system [34, 35].