Propionic acidemia

Propionic acidemia, also known as propionic aciduria, or sometimes referred to as ketotic glycinemia, is an autosomal recessive amino acid disorder, classified as a branched-chain organic acidemia,^[1] which presents in the early neonatal period with progressive encephalopathy.

Death can occur quickly, due to secondary hyperammonemia, infection, cardiomyopathy, or basal ganglial stroke.^[2]

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Diagnosis

Mutations in both copies of the PCCA or PCCB genes cause propionic acidemia.^[3] These genes are responsible for the formation of the enzyme propionyl-CoA carboxylase (EC 6.4.1.3), referred to as PCC.

PCC is required for the normal breakdown of the essential amino acids valine, isoleucine, threonine, and methionine, as well as certain odd-chained fatty-acids. Mutations in the PCCA or PCCB genes disrupt the function of the enzyme, preventing these acids from being metabolized. As a result, propionyl-CoA, propionic acid, ketones and other toxic compounds accumulate in the blood, causing the signs and symptoms of propionic acidemia.

Symptoms

Propionic acidemia is characterized almost immediately in newborns. Symptoms include poor feeding, vomiting, dehydration, acidosis, low muscle tone (hypotonia), seizures, and lethargy. The effects of propionic acidemia quickly become life-threatening.

Prevalence

  Propionic acidemia is inherited in an autosomal recessive pattern and is found in about 1 in 35,000^[3] live births in the United States. The condition appears to be more common in Saudi Arabia,^[4] with a frequency of about 1 in 3,000^[3]. The condition also appears to be common in Amish and Mennonite populations.^[5]

References

See also

• Methylmalonic acidemia
• Isovaleric acidemia
• Maple syrup urine disease