PCBD1

pterin-4 alpha-carbinolamine dehydratase 1

The PCBD1 gene provides instructions for making an enzyme called pterin-4 alpha-carbinolamine dehydratase. This enzyme helps carry out one step in the chemical pathway that recycles a molecule called tetrahydrobiopterin (BH4).

Tetrahydrobiopterin plays a critical role in processing several protein building blocks (amino acids) in the body. For example, it works with the enzyme phenylalanine hydroxylase to convert an amino acid called phenylalanine into another amino acid, tyrosine. Tetrahydrobiopterin is also involved in reactions that produce chemicals called neurotransmitters, which transmit signals between nerve cells in the brain. Because it helps enzymes carry out chemical reactions, tetrahydrobiopterin is known as a cofactor.

When tetrahydrobiopterin interacts with enzymes during chemical reactions, the cofactor is altered and must be recycled to a usable form. Pterin-4 alpha-carbinolamine dehydratase is one of two enzymes that help recycle tetrahydrobiopterin in the body.

At least nine mutations in the PCBD1 gene have been found to cause tetrahydrobiopterin deficiency. When this condition results from PCBD1 gene mutations, it is known as pterin-4 alpha-carbinolamine dehydratase (PCD) deficiency. PCD deficiency accounts for about 5 percent of all cases of tetrahydrobiopterin deficiency.

Some mutations in the PCBD1 gene change single amino acids in pterin-4 alpha-carbinolamine dehydratase, while other mutations introduce a premature stop signal in the instructions for making this enzyme. Changes in pterin-4 alpha-carbinolamine dehydratase reduce the enzyme's activity, which affects the body's ability to recycle tetrahydrobiopterin. As a result, less of this cofactor is available to participate in chemical reactions such as the conversion of phenylalanine to tyrosine. If phenylalanine is not converted to tyrosine, the excess can build up in the bloodstream and other tissues.

Although people with PCD deficiency usually have elevated levels of phenylalanine in the blood, this form of tetrahydrobiopterin deficiency rarely causes significant medical problems. Researchers believe that other enzymes may compensate for the reduced activity of pterin-4 alpha-carbinolamine dehydratase in people with PCBD1 gene mutations.

Cytogenetic Location: 10q22, which is the long (q) arm of chromosome 10 at position 22

Molecular Location: base pairs 70,882,280 to 70,888,786 on chromosome 10 (Homo sapiens Annotation Release 108, GRCh38.p7) (NCBI)

Cytogenetic Location: 10q22, which is the long (q) arm of chromosome 10 at position 22
  • 4-alpha-hydroxy-tetrahydropterin dehydratase
  • 6-pyruvoyl-tetrahydropterin synthase/dimerization cofactor of hepatocyte nuclear factor 1 alpha (TCF1)
  • Carbinolamine-4a-dehydratase
  • DCOH
  • Dimerization cofactor of hepatocyte nuclear factor 1-alpha
  • Dimerization cofactor of HNF1
  • PCBD
  • PCD
  • Phenylalanine hydroxylase-stimulating protein
  • PHS_HUMAN
  • Pterin-4-alpha-carbinolamine dehydratase
  • pterin-4 alpha-carbinolamine dehydratase/dimerization cofactor of hepatocyte nuclear factor 1 alpha
  • pterin-4 alpha-carbinolamine dehydratase/dimerization cofactor of hepatocyte nuclear factor 1 alpha (TCF1)
  • Pterin-4a-carbinolamine dehydratase (dimerization cofactor of hepatic nuclear factor 1-alpha)
  • Pterin carbinolamine dehydratase