Researchers at University of California at San Diego, and 22 other US national and international centers studied the clinical, biochemical, and molecular findings in a cohort of 38 patients with sepiapterin reductase deficiency (SRD). The phenotype and treatment response were assessed by chart and literature review. Average age of onset is 7 months, and delay to diagnosis is 9.1 years. Symptoms in infancy or childhood include motor and language delays, axial hypotonia, dystonia, weakness, oculogyric crises, with diurnal fluctuation, benefitted by sleep. Cerebral palsy is a common misdiagnosis. CSF showed low 5-hydroxyindoleacetic acid and homovanillic acid and elevated biopterin and sepiapterin. Diagnosis is confirmed by mutation analysis and/or enzyme activity in cultured fibroblasts. All patients treated with l-dopa in combination with carbidopa showed dramatic improvement. Early diagnosis and treatment are recommended. 
COMMENT. A diagnosis of SRD should be considered in patients with developmental delay, dystonia, axial hypotonia and atypical presumed cerebral palsy.