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3-phosphoglycerate dehydrogenase deficiency

  • What is 3-phosphoglycerate dehydrogenase deficiency?

    3-phosphoglycerate dehydrogenase deficiency is an inherited disorder caused by the inability of the body to make serine, which is building block for protein. This is due to a dysfunctional enzyme called phosphoglycerate dehydrogenase. Affected infants typically are born with small heads or head sizes that progressively get smaller as the child ages. This is due to loss of brain cells and brain tissue as a result of the lack of serine for brain development. Affected children typically have seizures, severe delays in achieving developmental milestones and involuntary momentary loss of muscle use and coordination. They will also have intellectual disability. In some very rare cases, affected individuals will not show signs or symptoms of the disorder until adolescence or adulthood. There is no cure for 3-phosphoglycerate dehydrogenase deficiency and only in some cases has supplemental dietary serine had any positive effect. 3-phosphateglycerate dehydrogenase deficiency is caused by pathogenic variants in the PHGDH gene.

  • How is 3-phosphoglycerate dehydrogenase deficiency inherited?

    3-phosphoglycerate dehydrogenase deficiency is inherited in an autosomal recessive manner. This type of inheritance requires the presence of two copies of a pathogenic variant for a person to have the genetic disease. Both parents must be carriers of a pathogenic variant in the gene in order to be at risk to have an affected child. The child must inherit a pathogenic variant from each carrier parent in order to be affected. There is a 1 in 4 chance that a baby will inherit two mutated copies of the gene and be affected when both parents are carriers.

  • What does it mean to be a carrier?

    There are generally no signs or symptoms associated with being a carrier for 3-phosphoglycerate dehydrogenase deficiency. However, the risk to have a child affected with 3-phosphoglycerate dehydrogenase deficiency is increased. Testing of reproductive partners is recommended for carriers of 3-phosphoglycerate dehydrogenase deficiency.

  • How common is 3-phosphoglycerate dehydrogenase deficiency?

    3-phosphoglycerate dehydrogenase deficiency is a very rare disorder. It is unknown exactly how often 3-phosphoglycerate dehydrogenase deficiency occurs.

  • What is analysed?

    Full gene sequencing

AFFECTED SYSTEMS
Brain
Muscle
CARRIER RATES
Ethnicity Detection Rate Carrier Frequency
General Population 99% 1 in 500