6-Pyruvoyltetrahydropterin synthase deficiency

6-Pyruvoyltetrahydropterin synthase deficiency is an autosomal recessive disorder that causes malignant hyperphenylalaninemia, a persistent rise of the amino acid phenylalanine, because the body lacks enough tetrahydrobiopterin. Commonly reported symptoms are low muscle tone in the trunk at first, later stiffness in the limbs, slowed movement, cogwheel rigidity, generalised dystonia and a marked variation in symptoms over the day. Other reported features include difficulty swallowing, oculogyric crises, sleepiness, irritability, raised temperature and seizures. Treatment options include neurotransmitter precursors such as levodopa and 5-hydroxytryptophan, monoamine oxidase inhibitors and tetrahydrobiopterin, with a variable response and an unknown long-term outcome. This entry records the condition as a named clinical entity and is not medical advice; diagnosis and care belong to a qualified clinician.