This disorder occurs through a mutation in the SPR gene, which is responsible for encoding the signals that create<unk><unk>  enzyme. The enzyme is involved in the last step of producing tetrahydrobiopterin better known as BH4. BH4 is involved in the processing of amino acids and the production of neurotransmitters, specifically that of dopamine and serotonin which are primarily used in transmission of signals between nerve cells in the brain. The mutation in the SPR gene interferes with the production of the enzyme by producing enzymes with little or no function at all. This interference results in a lack of BH4 specifically in the brain. The lack of BH4 only occurs in the brain because other parts of the body adapt and utilize alternate pathways for the production of BH4. The mutation in the SPR gene leads to nonfunctional<unk><unk>  enzymes, which results in a lack of BH4 and ultimately disrupts the production of dopamine and serotonin in the brain. The disruption of dopamine and serotonin production leads to the visible symptoms present in patients suffering from<unk> . SR deficiency is considered an inherited autosomal recessive condition disorder because each parent carries one copy of the mutated gene, but typically do not show any signs or symptoms of the condition.
Sepiapterin reductase deficiency
Enolase deficiency
Holocarboxylase synthetase deficiency
Ornithine translocase deficiency
Carbamoyl phosphate synthetase I deficiency
Malonyl-CoA decarboxylase deficiency
Glutathione synthetase deficiency
Mevalonate kinase deficiency