Organic acidemia

Organic Acidemia
Synonyms	N/A
Pronounce	N/A
Specialty	N/A
Symptoms	Vomiting, lethargy, hypotonia, developmental delay
Complications	Metabolic acidosis, seizures, coma
Onset	Neonatal or infancy
Duration	Chronic
Types	N/A
Causes	Genetic mutation
Risks	Family history
Diagnosis	Newborn screening, blood test, urine test
Differential diagnosis	N/A
Prevention	N/A
Treatment	Dietary management, supplementation, medication
Medication	N/A
Prognosis	Variable
Frequency	Rare
Deaths	N/A

Organic acidemia refers to a group of metabolic disorders characterized by the accumulation of organic acids in the body due to defects in the metabolism of certain amino acids, fats, or carbohydrates. These disorders are typically inherited in an autosomal recessive manner and can lead to severe metabolic acidosis and other complications if not managed appropriately.

Pathophysiology

Organic acidemias result from defects in the enzymes responsible for the breakdown of specific amino acids, fatty acids, or other compounds. This leads to the accumulation of organic acids in the blood and urine, which can be toxic to the body. The accumulation of these acids can disrupt normal metabolic processes, leading to acidosis, hypoglycemia, and hyperammonemia.

Types of Organic Acidemia

There are several types of organic acidemias, each associated with a specific enzyme deficiency:

• Methylmalonic acidemia (MMA): Caused by a deficiency in the enzyme methylmalonyl-CoA mutase or defects in the metabolism of vitamin B12.
• Propionic acidemia (PA): Results from a deficiency in the enzyme propionyl-CoA carboxylase.
• Isovaleric acidemia (IVA): Caused by a deficiency in the enzyme isovaleryl-CoA dehydrogenase.
• Glutaric acidemia type I (GA1): Due to a deficiency in the enzyme glutaryl-CoA dehydrogenase.

Clinical Presentation

Symptoms of organic acidemia can vary depending on the specific disorder and the severity of the enzyme deficiency. Common symptoms include:

• Vomiting
• Lethargy
• Hypotonia
• Developmental delay
• Seizures
• Coma

Diagnosis

Diagnosis of organic acidemia is often made through newborn screening programs, which can detect elevated levels of specific organic acids in the blood. Further diagnostic tests include:

• Blood tests to measure levels of organic acids and ammonia.
• Urine tests to detect organic acid metabolites.
• Genetic testing to identify specific enzyme deficiencies.

Management

Management of organic acidemia involves dietary modifications and medical interventions to prevent metabolic crises:

• Dietary management: Restriction of specific amino acids or proteins that cannot be properly metabolized.
• Supplementation: Use of carnitine or vitamin B12 supplements, depending on the specific disorder.
• Medication: Use of medications to reduce ammonia levels or to provide alternative metabolic pathways.

Prognosis

The prognosis for individuals with organic acidemia varies depending on the type and severity of the disorder. Early diagnosis and management can improve outcomes and prevent severe complications.

Research and Future Directions

Research is ongoing to better understand the genetic and biochemical basis of organic acidemias and to develop new treatments. Gene therapy and enzyme replacement therapy are potential future treatment options.

See Also

• Metabolic disorder
• Inborn error of metabolism
• Amino acid metabolism

External Links

• National Human Genome Research Institute - Organic Acidemias
• NIH Rare Diseases - Organic Acidemias

NIH genetic and rare disease info

• NIH info on Organic acidemia

Organic acidemia is a rare disease.