GTR Home > Conditions/Phenotypes > Mitochondrial complex II deficiency

Summary

Complex II, also known as succinate dehydrogenase (EC 1.3.5.1), is part of the mitochondrial respiratory chain. Deficiency of complex II is characterized by highly variable phenotypic expression. [from OMIM]

Associated genes

Clinical features

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  • Babinski sign
  • Muscle weakness
  • Hyperreflexia
  • Short stature
  • Neonatal hypotonia
  • Increased serum lactate
  • Developmental regression
  • Progressive leukoencephalopathy
  • Cognitive impairment
  • Seizures
  • Ragged-red muscle fibers
  • Ataxia
  • Spasticity
  • Dystonia
  • Myoclonus
  • Flexion contracture
  • Hypertrophic cardiomyopathy
  • Dilated cardiomyopathy
  • Leukoencephalopathy
  • Exercise intolerance
  • Stress/infection-induced lactic acidosis
  • Decreased activity of mitochondrial complex II
  • Abnormal mitochondria in muscle tissue
  • Increased intramyocellular lipid droplets
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