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Mitochondrial oxidative phosphorylation disorders in children: Phenotypic, genotypic and biochemical correlations in

Kothari Sonam1, Parayil Sankaran Bindu2, M M Srinivas Bharath3

  • 1Department of Clinical Neurosciences, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India; Neuromuscular Laboratory, Neurobiology Research Centre, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India.

Mitochondrion
|November 10, 2016
PubMed

Insights

Mitochondrial oxidative phosphorylation (OXPHOS) disorders in children present with diverse neuromuscular symptoms. This Indian study correlated enzyme deficiencies with clinical, imaging, and genetic data, revealing significant heterogeneity.

Area of Science:

  • Biochemistry
  • Pediatric Neurology
  • Genetics

Background:

  • Mitochondrial oxidative phosphorylation (OXPHOS) disorders are a significant cause of pediatric neuromuscular diseases.
  • Accurate diagnosis requires integrating biochemical, clinical, imaging, and genetic data.

Purpose of the Study:

  • To investigate the spectrum of mitochondrial OXPHOS disorders in a large cohort of Indian children with neuromuscular conditions.
  • To correlate biochemical enzyme deficiencies with clinical phenotypes, imaging, histopathology, and genetic findings for diagnostic clarification.

Main Methods:

  • Assay of mitochondrial respiratory chain enzymes in muscle tissue from 85 children between June 2011 and December 2013.
  • Correlation of enzyme deficiencies with neurological findings, magnetic resonance imaging (MRI), histopathology, and genetic analysis (mtDNA, SURF1, POLG1&2).
  • Classification of patients into syndromic and non-syndromic presentations.

Main Results:

  • The most frequent deficiency was isolated complex I (60%), followed by multiple complexes (27%).
  • Common neurological presentations included ataxia (59%), hypotonia (59%), and involuntary movements (49%).
  • Genetic analysis identified variations in mitochondrial DNA (n=8), SURF1 (n=5), and POLG1 (n=3).

Conclusions:

  • Mitochondrial OXPHOS disorders in children exhibit a wide range of clinical and imaging phenotypes.
  • Significant genetic heterogeneity underlies these disorders, necessitating comprehensive diagnostic approaches.
  • This study provides crucial insights into pediatric mitochondrial disorders in India.

Keywords:
Oxidative phosphorylation disordersPOLG1SURFmtDNA

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