[GTP cyclohydrolase 1-deficient dopa-responsive hereditary dystonia].

GTP cyclohydrolase 1-deficient dopa- responsive dystonia is an autosomal dominant disorder caused by mutations in the guanosine triphospate (GTP) cyclohydrolase 1 gene (GTP-CH1) with incomplete penetrance. This gene is involved in the synthesis of dopamine. It is the dystonia with clinically significant response to levodopa within the group of neurotransmitter inborn errors. We report a case of seven years old female. Her initial symptoms were gait difficulties caused by right foot dystonia with aggravation of symptoms toward the evening. The laboratory studies and neuroimaging were normal. A therapeutic trial with levodopa was started with a dramatic response to low doses. Concentrations of total neopterin (NP) in cerebrospinal fluid (CSF) were reduced. Mutation analysis of the gene GCH1 confirmed the disease (p.W96X, nucleotide change c. 287G>A). After one year of levodopa therapy, we obtained maximum benefit with levodopa/decarboxylase inhibitor with absence of adverse effects.