Neuropediatrics 2012; 43 - VS12_04
DOI: 10.1055/s-0032-1307164

Video documentation of a case of Dopa responsive Dystonia in early infancy: a rare but important diagnosis

S Bürki 1, S Strozzi 1, B Thöny 2, M Steinlin 1
  • 1Inselspital Bern, Universitätsklinik für Kinderheilkunde Abteilung für Neuropädiatrie, Entwicklung und Rehabilitation, Bern, Switzerland
  • 2Universitäts Kinderkliniken, Kinderspital Zürich, Abt. Klinische Chemie und Biochemie, Zürich, Switzerland

Introduction: As a disorder of BH4 metabolism Dopa responsive Dystonia (DRD) may present without hyperphenylalaninemia. DRD is caused by an autosomal dominant mutation in the GCH-1 gene, encoding the GTP cyclohydrolase I (GTPCH) that is involved in the cofactor biosynthesis of the hepatic apoenzyme phenylalanine-3-hydrocylase. Usually plasma hyperphenylalaninemia is detected in newborn screening (Guthrie). Here we describe a clinical case of GTPCH deficiency without hyperphenylalaninemia and show the video documentation of dramatic improvement after L-Dopa substitution.

Case Report: An 11-month old girl was referred for motor developmental delay obvious since the age of 9 months. She is the second child of healthy, nonconsanguineous Swiss parents. Family history is unremarkable. She was born after an uneventful pregnancy (birthweight 4050g) without perinatal or neonatal complications, newborn screening was normal. At examination there was truncal hypotonia and hypertonic posturing of extremities with diurnal fluctuation, there was intermittent head tremor. She was moving in a type of frog walk, a type of strange dystonic posturing on prone position.

Magnetic resonance imaging was normal, but CSF neurotransmitter analysis revealed low biopterin and neopterin concentrations. An oral phenylalanine-loading test revealed biopterin and neopterin to be very low. Skin biopsy adds up a reduced GTPCH activity in fibroblasts, mutation analysis of GCH1 gene is pending.

Treatment with L-Dopa supplementation was started in increasing dosage at the age of 15 months. Already after 10 days of treatment she was able to sit and started to crawl, 2 months later she walked hand-held.

Conclusion: This case illustrates an atypical presentation of strongly suspected Segawas disease and impressive video documentation of Dopa responsiveness. The diagnosis of this disorder is important, early treatment can enable striking clinical improvement with age appropriate development.

Dopa responsiveness - GTP cyclohydrolase I - Dystonia in early infancy