Sepiapterin reductase deficiency

Sepiapterin reductase deficiency is a condition characterized by movement problems, most often a pattern of involuntary, sustained muscle contractions known as dystonia. Other movement problems can include muscle stiffness (spasticity), tremors, problems with coordination and balance (ataxia), and involuntary jerking movements (chorea). People with sepiapterin reductase deficiency can experience episodes called oculogyric crises. These episodes involve abnormal rotation of the eyeballs; extreme irritability and agitation; and pain, muscle spasms, and uncontrolled movements, especially of the head and neck. Movement abnormalities are often worse late in the day. Most affected individuals have delayed development of motor skills such as sitting and crawling, and they typically are not able to walk unassisted. The problems with movement tend to worsen over time.

People with sepiapterin reductase deficiency may have additional signs and symptoms including an unusually small head size (microcephaly), intellectual disability, seizures, excessive sleeping, and mood swings.