Effects of L-5-hydroxytryptophan on monoamine and amino acids turnover in the Lesch-Nyhan syndrome.

In a patient with the Lesch-Nyhan syndrome we found decreased spinal fluid 5-hydroxyindole acetic acid (5-HIAA), the major metabolite of serotonin, and decreased homovanillic acid (HVA), the major metabolite of dopamine, indicating a decrease in monoamine metabolism. Administration of 5-hydroxytryptophan and carbidopa produced an increase in spinal fluid 5-HIAA, indicating that it might be possible to correct the serotonin deficiency in this syndrome, but there were no changes in the marked mental retardation and neurological deficits. Self-mutilation appeared to be suppressed by therapy but the effectiveness of the drugs decreased with time. There were also changes in the spinal fluid concentration of amino acids that might affect brain protein synthesis. These changes were corrected during administration of 5-hydroxytryptophan and carbidopa.