ABSTRACT
Progressive encephalopathy characterized by severe truncal hypotonia, decreased spontaneous movements, muscular rigidity of the extremities, movement disorders, including distal chorea and dystonia, mental impairment, microcephaly, epileptic seizures, hyperphenylalaninemia (HPA), and defective synthesis of tetrahydrobiopterin (BH4) because of defective activity of GTP cyclohydrolase (GTPCH), 6-pyruvoyltetrahydropterin synthase (PTPS) or sepiapterin reductase (SR), and defective recycling of BH4 due to deficiency of dihydropteridine reductase (DHPR) or pterin-4a-carbinolamine dehydratase (PCD).
