bims-cytox1 Biomed News
on Cytochrome oxidase subunit 1
Issue of 2024‒06‒09
two papers selected by
Gavin McStay, Liverpool John Moores University
  1. Complex mitochondrial disease caused by the mutation of COX10 in a toddler: a case-report study.
  2. A novel homozygous pathogenic missense variant in COX6B1: Further delineation of the phenotype.
  1. Ann Med Surg (Lond). 2024 Jun;86(6): 3753-3756
    Complex mitochondrial disease caused by the mutation of COX10 in a toddler: a case-report study.
    Azita Tavasoli, Maryam Kachuei, Saeed Talebi, Shayan Eghdami.
      Introduction and importance: Cytochrome C oxidase (COX) deficiency is an uncommon inherited metabolic disorder. It is identified by a lack of the COX, also known as Complex IV. This enzyme plays a crucial role in the rate-limiting and oxygen-accepting step of the respiratory chain within the subcellular structures called mitochondria. The deficiency of COX can either be restricted to skeletal muscle tissues or can impact multiple tissues throughout the body.Case presentation: A 3-year-old girl was admitted due to muscle weakness and a decline in developmental milestones 7 days after a significant stressor. Leukodystrophy was observed in the brain magnetic resonance imaging, and genome sequencing identified a homozygous mutation in exon 1 and 7 of chromosome 17. This mutation led to a deficiency in COX10, which is a component of mitochondrial complex IV.
    Clinical discussion: In the medical field, inherited metabolic disorders can be complex to diagnose due to overlapping symptoms with other conditions. Mitochondria's oxidative phosphorylation system, including the COX enzyme complex, plays a crucial role in energy production. Mitochondrial disorders, including COX deficiency, can present at various stages of life with diverse symptoms. Treatment options focus on supportive care and potential benefits from supplements like coenzyme-Q10 and small-molecule therapies targeting mitochondrial function. Identifying genetic mutations is key for advancing treatments in this area.
    Conclusion: This report presents a unique case of developmental regression and muscle weakness in a paediatric patient, which can be attributed to a rare occurrence of type 3 nuclear mitochondrial complex IV deficiency.
    Keywords:  COX10; case report; cytochrome c oxidase deficiency; mitochondrial complex IV; mitochondrial disorder
    DOI:  https://doi.org/10.1097/MS9.0000000000002096
  2. Am J Med Genet A. 2024 Jun 06. e63783
    A novel homozygous pathogenic missense variant in COX6B1: Further delineation of the phenotype.
    E Jennions, M Olsson-Engman, K Visuttijai, Å Wiksell, N Fluriach Dominguez, G Kollberg, A Oldfors, C Hedberg-Oldfors.
      Cytochrome c oxidase (COX) deficiency is a phenotypically diverse group of diseases caused by variants in over 30 genes. Biallelic pathogenic variants in COX6B1 have been described in four patients to date with varying disease manifestations. We describe the clinical features and follow-up of a patient with a novel homozygous pathogenic variant in COX6B1 who presented acutely with severe encephalomyopathy associated with an infection. New findings include ophthalmological evaluation and follow-up of neuroradiological investigations. The novel p.Trp31Arg variant was predicted to be pathogenic in silico, and further functional analyses with biochemical analysis of mitochondrial function showed isolated COX deficiency. Muscle biopsy showed a specific lack of COX6B1 protein together with complex IV deficiency on western blot, enzyme histochemistry, and immuno-histochemistry.
    Keywords:  COX deficiency; COX6B1; cavitating leukoencephalopathy
    DOI:  https://doi.org/10.1002/ajmg.a.63783
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