[A case of idiopathic renal hypouricemia].

Hypouricemia, as defined by serum uric acid levels less than 2.0 mg/dl, is rare in U.S.A, but it is relative in common in Japan. Hypouricemia occurs in various pathological conditions, including Wilsons disease, Fanconi syndrome, primary biliary cirrhosis and Sjõgrens syndrome as a result of renal tubular damage 1) . Idiopathic renal hypouricemia is a disorder characterized by impaired urate handling in the renal tubules. Most patients are clinically silent, but hematuria, urolithiasis or acute renal failure (ARF) may develop 2-6) . Recently, human urate transporter 1 (hURAT1), a urate anion exchanger that regulates blood uric acid levels, was identified in the human kidney and mutations in SLC22A12 gene encoding hURAT1 cause renal hypouricemia 7, 8) . We describe a case of idiopathic renal hypouricemia, and we demonstrate a mutation in the responsible gene (SLC22A12).