Tetrahydrobiopterin deficiency

Tetrahydrobiopterin deficiency is a condition characterized by a deficiency in a molecule called tetrahydrobiopterin or BH4. This condition alters levels of several body substances including neurotransmitters (which transfer signals between cells and the brain) and phenylalanine (the building blocks of proteins). Infants with BH4 deficiency usually appear normal at birth, but symptoms can present themselves over time. These include: intellectual disability, movement disorders, difficulty swallowing, seizures, and an inability to control body temperature. This deficiency is caused by a mutation in one of several genes (GCH1, PCBD1, PTS, or QDPR). BH4 deficiencies can be treated with BH4 supplements (2-20mg/kg per day) or a diet to regulate blood phenylalanine concentration. This condition is inherited in an autosomal recessive pattern meaning that two copies of a specific gene must be altered to produce this condition.