Tyrosine Hydroxylase Deficiency in Taiwanese Infants

Abstract 

We analyzed the clinical manifestations, genetic mutations, treatment responses to l-dopa, and long-term neurologic outcomes in Taiwanese infants with tyrosine hydroxylase deficiency. From 1999 to May 2011, we enrolled six infants who had been diagnosed with tyrosine hydroxylase deficiency by identifying point mutations on the tyrosine hydroxylase gene. Two patients manifested fetal distress during the perinatal period. Four patients exhibited generalized tremor as their first observed neurologic sign at age 3 months. All presented brisk reflexes, hypokinesia, rigidity, distal chorea, and athetosis. We identified a novel missense mutation, I382T, and report on the first patient, to the best of our knowledge, with a homozygous R153X nonsense mutation. Five of six patients responded to l-dopa at a dose of 4.2-34.7 mg/kg/day combined with biperiden or selegiline or both. Long-term neurologic outcomes (median follow-up, 5 years and 10.5 months) revealed two patients demonstrated slightly low intelligence quotients, three demonstrated mild to moderate psychomotor retardation, and one died of respiratory failure. A higher dose of l-dopa, together with alternative therapies, may lead to improvements in motor function. However, several years of observation may be needed to reach definitive conclusions about neurologic outcomes.