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Acyl-CoA dehydrogenase 9 deficiency

Synonym(s) ACAD9 deficiency
Prevalence Unknown
Inheritance Autosomal recessive
Age of onset Infancy
  • E71.3
MeSH -
MedDRA -


Disease definition

Acyl-CoA dehydrogenase 9 (ACAD9) deficiency is a rare disorder leading to a deficiency of complex I of the respiratory chain and is characterized by neurological dysfunction, hepatic failure and cardiomyopathy.


The prevalence is unknown.

Clinical description

Patients present predominantly with neurological, hepatic and /or cardiomyopathic disease with isolated NADH-CoQ reductase deficiency (see this term). Manifestations include failure to thrive, hypertrophic cardiomyopathy, exercise intolerance, liver disease and mild to severe neurological dysfunction.


ACAD9 deficiency is caused by a mutation in the ACAD9 gene (3q21.3) that encodes the protein ACAD9. This protein has only relatively recently been described but is quite widely expressed in tissues and has activity as an acyl-CoA dehydrogenase with overlapping substrate specificity with very long-chain acyl-CoA dehydrogenase (VLCAD). It also acts an assembly factor for complex I of the respiratory chain and therefore has a vital role in the production of a functioning mitochondrial respiratory chain.

Genetic counseling

The mode of inheritance is autosomal recessive and genetic counseling is possible.

Expert reviewer(s)

  • Dr Simon OLPIN

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