Caused by changes in GCH1, which encodes the first enzyme in making tetrahydrobiopterin (BH4), a cofactor needed to produce dopamine and serotonin. A change in one copy causes dopa-responsive dystonia, often with reduced penetrance, while changes in both copies cause severe deficiency.
Příznaky a projevy
Dopa-responsive dystonia usually begins in childhood with stiffness and turning-in of a foot that affects walking, and is typically worse later in the day. It can spread to other limbs, and some adults develop features of parkinsonism. The recessive form presents in infancy with progressive developmental problems, movement disorders and seizures, and raised phenylalanine is present from early infancy.
Co se diagnózou změní
Dopa-responsive dystonia responds dramatically and lastingly to low doses of levodopa, so recognising it is important. The recessive form needs specialist metabolic care. Genetic counselling and testing of relatives are appropriate, noting that people with one changed copy may never develop symptoms.
Analyzované geny
Známé také jako
GTP-cyclohydrolase I deficiency
Zahrnuje 3 příbuzných podtypů ↓Skrýt podtypy ↑
- dystonia 5
- dystonia, dopa-responsive, with or without hyperphenylalaninemia, autosomal recessive
- GTP cyclohydrolase I deficiency with hyperphenylalaninemia
