Hereditary xanthinuria is a rare disorder of purine metabolism that results from a marked decreased of xanthine oxidase (EC 1. 2. 3. 2) activity. In Japan, only 2 cases with xanthinuria have been reported. For last tow years (1980-1981) we experienced four Japanese patients with hypouricemia, hypouricosuria and xanthinuria. We report here the biochemical features of four cases with hereditary xanthinuria.
Case 1 was a 50-year-old woman who was initially diagnosed Graves's diseas in 1968, but otherwise well. Case 2 was a 67-year-old man who had a renal stone and died of renal tumor in the middle of this study. Case 3 was a 39-year-old man who was combined chronic renal failure. And his younger brother was case 4 who has been healthy.
A revers phase high-performance liquid chromatography (HPLC) was used to the determination of hypoxanthine, xanthine, uric acid and allopurinol (4-hydroxypyrazolo-(3, 4-d) pyrimidine) in human urine Urinary hypoxanthine concentration was 1.3-5.4 mg/100ml, urinary xanthine concentration was 11.3-26.1 mg/100ml and the ratio (by moler) of xanthine to oxypurine (hypoxanthine+xanthine) was 77-89% in four cases with xanthinuria.
In three cases (1, 3, 4) xanthine oxidase activity in extracts from jejunal mucosa was assayed by a ultraviolet spectrophotometric method, which depends on the enzymatic conversion of hypoxanthine to uric acid. The enzyme activity was marked decreased in all cases.
The findings of these biochemical features on four cases were suggested the presence of hereditary xanthinuria.
