Sepiapterin reductase deficiency is an inherited pediatric disorder characterized by movement problems, and most commonly displayed as a pattern of involuntary sustained muscle contractions known as dystonia. Symptoms are usually present within the first year of age, but diagnosis is delayed due to physicians lack of awareness and the specialized diagnostic procedures. Individuals with this disorder also have delayed motor skills development including sitting, crawling, and need assistance when walking. Additional symptoms of this disorder include intellectual disability, excessive sleeping, mood swings, and an abnormally small head size. SR deficiency is a very rare condition. The first case was diagnosed in 2001, and since then there have been approximately 30 reported cases. At this time, the condition seems to be treatable, but the lack of overall awareness and the need for a series of atypical procedures used to diagnose this condition pose a dilemma. Signs and symptoms
Cognitive problems
Intellectual disability: Delay in cognitive development
Extreme mood swings
Language delay

Motor problems
Dystonia: involuntary muscle contractions
Axial hypotonia: low muscle tone and strength
Dysarthria: impairment in muscles used for speech
Muscle stiffness and tremors
Seizures
Coordination and balance impairment
Oculogyric crises: abnormal rotation of the eyesThe oculogyric crises usually occur in the later half of the day and during these episodes patients undergo extreme agitation and irritability along with uncontrolled head and neck movements. Apart from the aforementioned symptoms, patients can also display parkinsonism, sleep disturbances, small head size (microcephaly), behavioral abnormalities, weakness, drooling, and gastrointestinal symptoms. Causes
This disorder occurs through a mutation in the SPR gene, which is responsible for encoding the sepiapterin reductase enzyme.
This analysis reveals decreased concentrations of homovanillic acid (HVA), 5-hydroxyindolacetic acid (HIAA), and elevated levels of 7,8-dihydrobiopterin, a compound produced in the synthesis of neurotransmitters. Sepiapterin is not detected by the regularly used methods applied in the investigation of biogenic monoamine metabolites in the cerebrospinal fluid. It must be determined by specialized methods that work by indicating a marked and abnormal increase of sepiapterin in cerebrospinal fluid. Confirmation of the diagnosis occurs by demonstrating high levels of CSF sepiapterin and a marked decrease of SR activity of the fibroblasts along with SPR gene molecular analysis. Treatment
Levodopa and Carbidopa
SR deficiency is currently being treated using a combination therapy of levodopa and carbidopa. These treatments are also used for individuals suffering from Parkinsons. The treatment is noninvasive and only requires the patient to take oral tablets 3 or 4 times a day, where the dosage of levodopa and carbidopa is determined by the severity of the symptoms. Levodopa is in a class of medications called central nervous system agents where its main function is to become dopamine in the brain. Carbidopa is in a class of medications called decarboxylase inhibitors and it works by preventing levodopa from being broken down before it reaches the brain. This treatment is effective in mitigating motor symptoms, but it does not totally eradicate them and it is not as effective on cognitive problems. Patients who have been diagnosed with SR deficiency and have undergone this treatment have shown improvements with most motor impairments including oculogyric crises, dystonia, balance, and coordination.