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Diseases Studied

Phenylalanine Hydroxylase Deficiency

Phenylalanine Hydroylase Deficiency (PAH Deficiency), also known as Phenylketonuria (PKU), is a genetic metabolic disorder that increases the body's levels of phenylalanine. Phenylalanine is one of the building blocks (amino acids) of proteins. Humans cannot make phenyalanine, but it is a natural part of the foods we eat. However, people do not need all the phenyalanine they eat, so the body converts extra phenylalanine to another harmless amino acid, tyrosine. People with PKU cannot properly break down the extra phenylalanine to convert it to tyrosine. This means phenylalanine builds up in the person's blood, urine, and body. If PKU is not treated, phenylalanine can build up to harmful levels in the body.

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Defects in Biopterin Synthesis or Recycling, or Tetrahydrobiopterin Deficiency (BH4 Deficiency), is a general term for a group of disorders characterized by abnormalities in the creation (biosynthesis) or regeneration of tetrahydrobiopterin, a naturally-occurring compound that acts as a cofactor. In most of these disorders, there are abnormally high levels of the amino acid phenylalanine (hyperphenylalaninemia). Symptoms can include progressive neurological abnormalities, lack of muscle tone (hypotonia), the overproduction of saliva (hypersalivation), loss of coordination, abnormal movements, and/or delayed motor development. The four main forms of the disorder include:

  • GTP cyclohydrolase 1 Deficiency
  • 6-Pyruvoyl-Tetrahydropterin Synthase Deficiency
  • DihydropteridineReductase Deficiency
  • Pterin-4a-Carbinolamine Dehydratase Deficiency
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DNAJC12 deficiency is a rare inborn error of metabolism characterized by increased serum phenylalanine. It is associated with various neurological symptoms ranging from mild autistic features or hyperactivity to severe intellectual disability, dystonia, and parkinsonism. Laboratory analyses show normal tetrahydrobiopterin (BH4) metabolism and low levels of the CSF monoamine neurotransmitter metabolites homovanillic acid and 5-hydroxyindoleacetic acid.

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