SLC7A9 and renal tubular acidosis: Several carriers of KSD-associated genes were identified including cystinuria (SLC3A1, N = 2 or SLC7A9, N = 1), xanthinuria type 1 (XDH, N = 2), osteopetrosis with renal tubular acidosis (CA2, N = 2), primary hyperoxaluria type 3 (HOGA1, N = 2), and hypophosphatemic rickets with hypercalciuria (SLC34A3, N = 1).