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Peroxisomal acyl-CoA oxidase deficiency

Synonym(s) Pseudo-NALD
Pseudo-neonatal adrenoleukodystrophy
Prevalence <1 / 1 000 000
Inheritance Autosomal recessive
Age of onset Neonatal
  • E71.3
  • C0342871
  • C1849678
  • C536662
MedDRA -


Disease definition

Peroxisomal acyl-CoA oxidase deficiency is a rare neurodegenerative disorder that belongs to the group of inherited peroxisomal disorders and is characterized by hypotonia and seizures in the neonatal period and neurological regression in early infancy.


Acyl-CoA oxidase deficiency is a rare disease with only 30-40 patients identified world-wide so far.

Clinical description

The disease manifests in the neonatal period with hypotonia (92%) and seizures (91%) as dominant features. Facial dysmorphism (50%) with hypertelorism, epicanthus, low nasal bridge, and low-set ears may be present. Some children have polydactyly and hepatomegaly. Psychomotor development is delayed, but children are usually able to walk and say a few words. However, neurological regression occurs usually at the age of 1-3 years (mean age: 28 months). Hypotonia is replaced by hypertonia with hyperreflexia. Epilepsy may become more severe and sensorineural hearing loss may appear. Strabismus, nystagmus, and optic atrophy can also occur.


Peroxisomal acyl-CoA oxidase deficiency is caused by mutations in the ACOX1 gene (17q25.1) encoding peroxisomal straight-chain acyl-CoA oxidase.

Diagnostic methods

Diagnosis is based on laboratory studies revealing increased serum very-long chain fatty acids (VLCFA) and markedly reduced acyl-CoA oxidase activity in fibroblasts. MRI examination of the brain shows abnormal white matter signals. Diagnosis can be confirmed by the presence of mutations in the ACOX1 gene.

Differential diagnosis

Differential diagnoses include Usher syndrome (see this term) and all causes of neonatal hypotonia. The other peroxisomal disorders should also be discarded, especially neonatal adrenoleukodystrophy (see this term), which presents similar clinical manifestations.

Antenatal diagnosis

Antenatal diagnosis is possible through biochemical and/or molecular analysis of amniocytes or chorionic villus cells.

Genetic counseling

Transmission is autosomal recessive. Genetic counseling should be offered to the families of patients.

Management and treatment

No specific treatment is available. Multidisciplinary supportive care should be offered.


Prognosis is unfavorable; death usually occurs at around 5 years from respiratory issues.

Expert reviewer(s)

  • Pr R.J.A. [Ronald] WANDERS

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