Synthase Deficiency with Mild Hyperphenylalaninemia

Severe 6-pyruvoyl-tetrahydrobiopterin synthase deficiency is a tetrahydrobiopterin deficiency disorder that presents in infancy with developmental delay, seizures, and abnor-mal movements associated with hyperphenylalaninemia usually detectable by neonatal phenylketonuria screening programs. We describe an 8-year-old girl with delay, sei-zures, and dystonia with mild hyperphenylalaninemia de-tected in late childhood. The diagnosis of 6-pyruvoyl-tetrahydrobiopterin synthase deficiency was made by analysis of pterins in urine, pterins and neurotransmitters in cerebrospinal fluid, and enzyme assay. The patient im-proved clinically taking oral tetrahydrobiopterin, levo-dopa/carbidopa, and 5-hydroxytryptophan. This treatable condition may not always be detected by routine popula-tion screening for hyperphenylalaninemia. Ann Neurol 2005;58:164–167 6-Pyruvoyl-tetrahydrobiopterin synthase (PTPS) defi-ciency is a recessively inherited neurometabolic condi-tion identified as the most common cause of tetrahy-drobiopterin (BH4) deficiency. It is the cause of approximately 60 % of all cases of BH4 deficiencies as listed in the BIODEF International database of Tetra-hydrobiopterin Deficiencie