Genetic polymorphisms in Solute Carrier Family 7 Member 9 (SLC7A9), an amino acid transporter known to be expressed in renal proximal tubule cells, cause cystinuria [20], are associated with GFR [5, 21], and have been identified as a risk factor for CKD patients of European ancestry [12]. The gene discussed is SLC7A9; the disease is cystinuria.