Movement Disorders Vol. 13, Nu. 2, 1998, p. 350 0 1998 Movement Disorder Society BE! S PP MEW

Editor Solicited Videotape

Infantile Parkinsonism-Dystonia: Hydroxylase Deficiency

Tyrosine

Robert Surtees, PhD, and Peter Clayton, MD

Institute of Child Health, University College London Medical School, London, U. K.

Infantile parkinsonism-dystonia is most commonly caused by inborn errors of metabolism affecting the do- pamine biosynthetic pathway. The inborn errors include those interrupting de novo synthesis of the cofactor tet- rahydrobiopterin (GTP-cyclohydrolase I deficiency and 6-pyruvoyltetrahydropterin synthase deficiency) or its reclamation (dihydropteridine reductase deficiency) in addition to those directly affecting the dopamine synthe- sis pathway (aromatic amino-acid decarboxylase defi- ciency and tyrosine hydroxylase deficiency).

The video shows a 6-month-old infant with tyrosine hydroxylase deficiency before and during treatment with levodopa (2 mgkg per day in five divided doses). Do- pamine deficiency was suspected from the clinical fea- tures and confirmed by finding a selective reduction in the concentration of homovanillic acid (an acidic dopa-

mine metabolite) in her cerebrospinal fluid. Cerebrospi- nal fluid tetrahydrobiopterin, dihydrobiopterin, neop- terin, and 3-methoxytyrosine concentrations were normal suggesting tyrosine hydroxylase deficiency; this was proven by molecular analysis.' The patient was homo- zygous for a point mutation (L205P) in the tyrosine hy- droxylase gene while her asymptomatic parents and brother were heterozygous for the mutation, indicating recessive inheritance. When last reviewed at the age of 4 years, there were no abnormal neurologic signs and her development was age appropriate.

REFERENCE 1. Ludecke B, Kndppskog PM, Clayton PT, et al. Recessively inher-

ited L-dopa-responsive parkinsonism in infancy caused by a point mutation (L205P) in the tyrosine hydroxylase gene. Hum Mot Genet 1996;5: 1023-1028.

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