This paper described a familial aggregation of subjects with xanthinuria, in which 3 of 4 siblings were affected.
The propositus was a 31- year old female in whom hypouricemia was discoverd incidentally during an investigation of her major medical problem , diabetes mellitus. Her serum urate was 0.9 mg/dl and 24-hour urinary excretion of uric acid was 17 mg. Her plasma oxypurine concentration was 0.62 mg/dl and 24-hour urinary oxypurine excretion was 292.7 mg , 70 percent of the latter was xanthine.
Her older brother and younger sister, who were entirely asymptomatic, were found to have xanthinuria during investigation of the family. Her father exhibited a slightly elevated excretion of oxypurines in his 24-hour urine and plasma xanthine of her mother was slightly increased. These findings suggest that they are heterozygotes.
Xanthine oxidase activity in their tissues will be determined in the near future.