Dopa responsive dystonia with Turner's syndrome: clinical, genetic, and neuropsychological studies in a family with a new mutation in the GTP-cyclohydrolase I gene.

A 26 year old woman with dopa responsive dystonia and cytogenetically confirmed Turner's syndrome had bilateral globus pallidus hypointensity on brain MRI. Among the living members of a five generation pedigree the patient's mother and the mother's sister also had dopa responsive dystonia; a maternal grandfather had senile parkinsonism, his niece isolated postural tremor. No other family member had Turner's syndrome. A new missense mutation in exon I of the gene of GTP-cyclohydrolase I was found in the three family members with dopa responsive dystonia. With levodopa substitution the patients with dopa responsive dystonia improved clinically as well as in quantitative tests on hand tapping, verbal and performance IQ, concept formation, and set shifting abilities.