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

Source: 

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