What are the Mitochondrial disorders?

Mitochondrial disorder:

It is also known as Mitochondrial disease or Mitochondrial syndrome. It is a group of disorders caused by a mutation in the Mitochondrial DNA or gene encoding for oxidative pathways.  Syndrome associated with Mitochondrial gene mutation:

MERRF (Myoclonic epilepsy with ragged red fibres): It includes

  • Myoclonic epilepsy
  • Cerebellar ataxia
  • Dementia
  • Sensorineural deafness with or without peripheral neuropathy
  • Optic atrophy, and
  • Multiple lipomas

MELAS (Mitochondrial encephalopathy, lactic acidosis and stroke-like episodes): It includes

  • Episodic encephalopathy
  • Stroke-like episodes often preceded by migraine-like headache
  • Nausea and vomiting

CPEO (Chronic progressive external ophthalmoplegia): It includes

  • Progressive ptosis and external
  • oculomotor palsy (main features)
  • Proximal myopathy with or without deafness
  • Ataxia, and
  • Cardiac conduction defects

Kearns–Sayre syndrome: It includes

  • Chronic progressive external ophthalmoplegia but at an early age (< 20 years)
  • Heart block
  • Retinitis pigmentosa
  • Myopathy, and
  • Diabetes

MNGIE (Mitochondrial neurogastrointestinal encephalomyopathy): It includes

  • Progressive ptosis
  • External oculomotor palsy
  • Gastrointestinal dysmotility (often pseudo-obstruction)
  • Diffuse leukoencephalopathy
  • Thin body habitus
  • Peripheral neuropathy and myopathy

NARP (Neuropathy, ataxia and retinitis pigmentosa): It includes

  • Weakness
  • Ataxia
  • Progressive loss of vision
  • Dementia
  • Seizures

LHON (Leber’s hereditary, optic neuropathy): 

Three-point mutations account for more than 90% of LHON cases. It is characterized by
  • Acute or sub-acute painless loss of vision
  • Most frequently in young boys
  • Due to bilateral optic atrophy

Usher’s syndrome: It includes

  • Deafness
  • Retinitis pigmentosa
  • Myopathy

  • Davidson: 1144, 49
  • Step up to MRCP: 1046
  • Sanjay Sharma: Q 315

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