Impaired urinary water excretion in a three-generation family

We report on a three-generation family (daughter, mother, and maternal gran dmother) with a syndrome of inappropriate secretion of antidiuretic hormone (SIADH)-like condition in the absence of inappropriate ADH secretion. In t he three females, a water load test showed severely reduced urinary water e xcretion, with the ratio of urine volume to the loaded water being 10-33% ( normal value: 70.2+/-7.8%). Urinary AQP2 excretion was normal, as was the D NA sequence of AVPR2 and AQP2. The results suggest the presence of a new do minantly inherited disorder for tubular water resorption.