Lesch-Nyhan Syndrome: report on two brothers.

Lesch-Nyhan syndrome is a rare X-linked disease characterized by over-production of uric acid and a central nervous system (CNS) disorder consisting of mental retardation, spasticity, choreoathetosis, and a compulsive form of self-mutilation. A deficiency in hypoxanthine-guanine phosphoribosyl transferase (HPRT) provides the underlying metabolic basis for this disease. A 12 month-old male baby who had orange crystals over the diapers since he was 3 months old was brought to our hospital due to developmental delay. Mental retardation and athetosis were also noted. Chemical analysis revealed hyperuricemia (uric acid 8.6 mg/dl). Urine routine showed microscopic hematuria and uric acid crystals. The activity of HPRT in erythrocyte lysates of parents were both within normal limits, but that of the patient was very low (0.0547 nm/min/mg protein, < 0.05% of control). His younger brother was born 2 months after this disorder diagnosed in this patient. The younger brother was noted to have uric acid crystals over the diapers when he was 40 days old and hyperuricemia (10.6 mg/dl) showed up later. He was also a case of Lesch-Nyhan syndrome since the activity of HPRT in erythrocyte lysates was also low (0.0327 nmol/min/mg protein, < 0.05% of control). Further studies, including carrier detection and deoxyribonucleic acid (DNA) analysis, could be helpful for genetic counseling. This syndrome is rare among Chinese, and this may be due to underdiagnosis.