Renal hypouricaemia in a patient with 48,XXYY syndrome

Studies on hypouricaemia observed in a patient with 48,XXYY syndrome revealed an abnormality in renal urate handling. His renal urate clearance was abnormally increased. Inosine administration and provocative tests using probenecid and pyrazinamide identified an isolated renal tubular abnormality with increased urate secretion. Since the serum urate in his brother with a normal sex chromosome constitution was also low, the association of renal hypouricaemia and 48,XXYY syndrome in this patient is probably coincidental. Although the brother was not investigated, these siblings may be a previously unreported case of familial hypouricaemia due to isolated renal hypersecretion.