Diff: ACOX1
Comparing revision #2 (2023-06-15 04:41:46) with revision #3 (2026-06-22 11:37:16).
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ACOX1, also known as Acyl-CoA Oxidase 1, is an enzyme encoded by the ACOX1 gene. This gene plays a crucial role in fatty acid metabolism within the peroxisomes, specialized cellular structures responsible for breaking down fatty acids and other metabolic processes. Mutations in the ACOX1 gene can lead to various disorders, including [[Mitchell Syndrome]], a rare neurological condition. |
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== Function and Role in Fatty Acid Metabolism == |
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ACOX1 is primarily involved in the breakdown of very long-chain fatty acids (VLCFAs) within the peroxisomes. It catalyzes the initial step of the fatty acid beta-oxidation pathway, converting VLCFAs into medium-chain fatty acids, which can be further metabolized for energy production. This process generates hydrogen peroxide as a byproduct, which is then efficiently detoxified by peroxisomal catalase. |
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== Clinical Significance and Mutations == |
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Mutations in the ACOX1 gene can lead to various metabolic disorders, collectively known as peroxisomal disorders. These disorders are characterized by impaired fatty acid oxidation and the accumulation of VLCFAs and BCFAs in tissues and body fluids. The specific mutations in ACOX1 can vary and may result in a range of clinical manifestations and disease severity. |
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'''ACOX1''' is the gene that provides instructions for making peroxisomal straight-chain acyl-CoA oxidase, an enzyme involved in breaking down very-long-chain fatty acids inside peroxisomes. |
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Some of the peroxisomal disorders associated with ACOX1 mutations include: |
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Peroxisomes are small cell structures that help process fatty acids and other molecules. ACOX1 acts early in peroxisomal fatty-acid beta-oxidation and produces hydrogen peroxide as a by-product, which is normally handled by other peroxisomal enzymes such as catalase. |
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* X-linked adrenoleukodystrophy (X-ALD) |
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* Refsum disease |
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* Acyl-CoA oxidase deficiency |
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== Function == |
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The ACOX1 enzyme helps shorten very-long-chain fatty acids so they can be further processed. This pathway is important because some fatty acids are too long to be handled efficiently by mitochondria alone. |
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Individuals with these disorders may experience neurological symptoms, such as progressive loss of motor function, impaired vision, and hearing loss. The severity and progression of symptoms can vary widely, even among individuals with the same ACOX1 mutation. |
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The gene is located on chromosome 17 and is also known by names such as acyl-CoA oxidase 1, palmitoyl-CoA oxidase and peroxisomal acyl-coenzyme A oxidase 1. |
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== ACOX1 Mutations and Mitchell Syndrome == |
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Certain mutations in the ACOX1 gene can lead to the development of Mitchell Syndrome, an extremely rare genetic disorder characterized by neurological impairments. Mitchell Syndrome was only recently identified due to advancements in genetic sequencing. |
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== Disease Associations == |
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Different kinds of ACOX1 variant can cause different clinical pictures. |
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In Mitchell Syndrome, a specific mutation occurs in the ACOX1 gene during the embryonic stage, resulting in a dysfunctional ACOX1 enzyme. This leads to an abnormal fatty acid metabolism within the peroxisomes. The impaired breakdown of VLCFAs causes an accumulation of hydrogen peroxide, which becomes toxic to the cells over time. |
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Biallelic loss-of-function variants can cause peroxisomal acyl-CoA oxidase deficiency, a rare inherited disorder beginning in infancy. MedlinePlus Genetics describes hypotonia, seizures, developmental problems, leukodystrophy, hearing and vision loss, and early severe neurological decline in many reported cases. |
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The buildup of hydrogen peroxide is particularly detrimental to Schwann cells, which are responsible for producing the myelin sheath surrounding nerves. The myelin sheath is essential for the proper conduction of nerve signals. In Mitchell Syndrome, the myelin sheath becomes damaged, leading to impaired axonal function. This results in mobility and balance issues, progressive loss of motor skills, and potential cognitive decline in some cases. |
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Specific de novo gain-of-function variants have been reported in Mitchell syndrome, a rare autosomal dominant neurodegenerative disorder associated with episodic demyelination, peripheral neuropathy and hearing loss. The mechanism is different from classical loss-of-function acyl-CoA oxidase deficiency. |
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== Diagnosis and Treatment == |
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The diagnosis of Mitchell Syndrome relies on genetic testing to identify specific mutations in the ACOX1 gene. Given the rarity of the condition, there are currently limited diagnostic and treatment options available. |
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ACOX1 should not be confused with genes that cause other peroxisomal disorders. For example, X-linked adrenoleukodystrophy is mainly associated with ABCD1, and classic Refsum disease is commonly associated with PHYH or PEX7. |
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Treatment for Mitchell Syndrome focuses on managing symptoms and providing supportive care to individuals affected by the condition. Physical therapy and rehabilitation programs may help maintain mobility and improve quality of life. Additionally, ongoing research is being conducted to explore potential gene therapies and novel treatment approaches that target the underlying genetic mutation in ACOX1. |
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== Diagnosis and Research == |
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Diagnosis of suspected ACOX1-related disease may involve clinical assessment, biochemical testing of very-long-chain fatty acids, brain imaging, nerve studies and genetic testing. |
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The diagnosis of ACOX1-related disorders involves clinical evaluation, genetic testing to identify mutations in the ACOX1 gene, and biochemical analysis to assess the accumulation of VLCFAs and BCFAs in tissues or body fluids. Early diagnosis is crucial for the implementation of appropriate treatment strategies. |
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Research has focused on how loss of enzyme function, gain of enzyme activity and oxidative stress affect glial cells, myelin and the nervous system. Because the conditions are rare, much of the literature is based on case reports, small series and experimental models. |
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Currently, there is no cure for ACOX1-related disorders. Treatment approaches focus on managing symptoms and preventing complications. This may include dietary modifications, the use of specific medications to control symptoms, and supportive therapies to address individual needs. |
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== See Also == |
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* [[Genetics]] |
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* [[Chromosome_17]] |
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* [[Mitchell_Syndrome]] |
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* [[Peroxisome]] |
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In addition to Mitchell Syndrome, mutations in the ACOX1 gene can lead to other peroxisomal disorders, such as ACOX1 deficiency. Although these disorders involve ACOX1 gene mutations, they exhibit distinct clinical manifestations, symptoms, and severity. |
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== References == |
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* [https://medlineplus.gov/genetics/gene/acox1/ MedlinePlus Genetics: ACOX1 gene] |
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* [https://www.ncbi.nlm.nih.gov/gene/51 NCBI Gene: ACOX1 acyl-CoA oxidase 1] |
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* [https://www.ncbi.nlm.nih.gov/medgen/376636 NCBI MedGen: Acyl-CoA oxidase deficiency] |
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* [https://thegencc.org/genes/HGNC%3A119 GenCC: ACOX1 gene disease validity] |
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* [https://pmc.ncbi.nlm.nih.gov/articles/PMC10318832/ PMC: A de novo heterozygous variant in ACOX1 gene causes Mitchell syndrome] |
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== Research and Future Directions == |
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Ongoing research aims to further understand the molecular mechanisms underlying ACOX1-related disorders and develop novel therapeutic approaches. Advances in gene therapy, enzyme replacement therapy, and small molecule interventions hold promise for potential future treatments. |
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[[Category:Genetics]] |
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[[Category:Medicine]] |