6-pyruvoyl-tetrahydropterin-synthase deficiency (PTPS) results in high levels of an amino acid called phenylalanine (hyperphenylalaninemia).
Individuals with PTPS deficiency may have delayed intellectual development, loss of coordination or delayed motor development, low muscle tone in the body (hypotonia) but increased muscle tone in the arms and legs (rigidity), and body temperature regulation issues. Symptoms can appear within the first 4-6 months of life, and the symptoms can vary greatly from individuals being mildly to severely affected. Treatments are available for this disorder and the impact of PTPS deficiency can be limited if it is recognized and treated early.
PTPS deficiency is caused by pathogenic (disease-causing) variants in the PTS gene and exhibits autosomal recessive inheritance. This means that both parents must be carriers to have a 25% chance to have a child with the condition.
Other names for this condition are tetrahydrobiopterin deficiency, hyperphenylalaninemia, BH4-deficient, A (HPABH4A), hyperphenylalaninemia, BH4-deficient, due to partial PTS deficiency, and hyperphenylalaninemia, tetrahydrobiopterin-deficient, due to PTS deficiency.
Resources:
National Organization for Rare Disorders
Revised July 2023
