Peroxisomal Acyl-CoA oxidase deficiency
Straight-chain Acyl-CoA oxidase deficiency
Peroxisomal acyl-CoA oxidase deficiency is a disorder that causes deterioration of nervous system functions (neurodegeneration) beginning in infancy. Newborns with peroxisomal acyl-CoA oxidase deficiency have weak muscle tone (hypotonia) and seizures. They may have unusual facial features, including widely spaced eyes (hypertelorism), a low nasal bridge, and low-set ears. Extra fingers or toes (polydactyly) or an enlarged liver (hepatomegaly) also occur in some affected individuals.
Most babies with peroxisomal acyl-CoA oxidase deficiency learn to walk and begin speaking, but they experience a gradual loss of these skills (developmental regression), usually beginning between the ages of 1 and 3. As the condition gets worse, affected children develop exaggerated reflexes (hyperreflexia), increased muscle tone (hypertonia), more severe and recurrent seizures (epilepsy), and loss of vision and hearing. Most children with peroxisomal acyl-CoA oxidase deficiency do not survive past early childhood.
- Abnormal electroretinogram
- Abnormality of metabolism/homeostasis
- Abnormality of visual evoked potentials
- Cognitive impairment
- Developmental regression
- EEG abnormality
- Gait disturbance
- Morphological abnormality of the central nervous system
- Muscular hypotonia
Peroxisomal acyl-CoA oxidase deficiency is a rare disorder. Its prevalence is unknown. Only a few dozen cases have been described in the medical literature.
Peroxisomal acyl-CoA oxidase deficiency is caused by mutations in the ACOX1 gene, which provides instructions for making an enzyme called peroxisomal straight-chain acyl-CoA oxidase. This enzyme is found in sac-like cell structures (organelles) called peroxisomes, which contain a variety of enzymes that break down many different substances. The peroxisomal straight-chain acyl-CoA oxidase enzyme plays a role in the breakdown of certain fat molecules called very long-chain fatty acids (VLCFAs). Specifically, it is involved in the first step of a process called the peroxisomal fatty acid beta-oxidation pathway. This process shortens the VLCFA molecules by two carbon atoms at a time until the VLCFAs are converted to a molecule called acetyl-CoA, which is transported out of the peroxisomes for reuse by the cell.
Reported prenatal diagnosis of acyl-CoA oxidase deficiency by analysis of amniotic fluid taken at 20 weeks's gestation. Plasmalogen synthesis was normal, but beta-oxidation activity was decreased. There was an abnormal accumulation of VLCFAs. Immunoblot analysis showed absence of the acyl-CoA oxidase protein.
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