Diseases

  

  Mitochondrial disease

  • Mitochondria are critical for cell function and defected forms are involved in a number of degenerative diseases, ageing and cancers.
  • The causes of mitochondrial disease can arise by mutations that are inherited or obtained in mitochondrial DNA.
  • Mutations in the nuclear genes that code for some of the mitochondrial proteins can also cause defects. 
  •  Unfavorable effect from infections, drugs or other environmental may also cause mitochondrial diseases.
  •  Mutations in the mitochondrial DNA usually impair the oxidative phosphorylation enzymes in the electron transport chain. This can have profound effects especially in tissues that depend on oxidative phosphorylation, like the brain, heart and muscles.
  • Mitochondrial mutations can therefore result in a wide range of disorders which include cancer, epilepsy, diabetes, and muscle, heart, kidney and liver conditions, deafness and blindness.
  • Some examples of mitochondrial disease are Neuropathy Ataxia and Retinitis Pigmenatosa, Leber's Hereditary and Chronic Progressive External Opthalmoplegia.

 

Neuropathy Ataxia and Retinitis Pigmentosa (NARP)

This disease usually presents in young adults and is caused by mutations that leads to impairment of the synthesis of the mitochondria’s ATP. This leads to a reduction in the cells production of cellular energy and also cell death. Patients suffer a number of symptoms, which include sluggish pupils, proximal muscle weakness, blindness, seizures, hearing loss and dementia and developmental delay.

 

Leber’s Hereditary 

This is an inherited form of vision loss and like NARP; it presents in young adults and is usually rare in early childhood or late adulthood. Defected mitochondria results from mutations in genes which are associated in the ATP synthesis mechanism. The cells in the optic nerve, which relay visual information to the brain, die and this subsequently causes vision loss in suffers. The condition is usually gradually and mainly effects central vision which is required for detailed vision. Conditions are usually permanent but in rare cases central vision can gradually improve. How the genetic defects cause the death of cells in the optic nerve remains yet unclear.

 

Chronic Progressive External Opthalmoplegia (CPEO) ptosis patient

The onset of this rare disorder is usually before the age of 20 and affects boys and girls equally. Mutations in the mitochondrial DNA results in defected proteins required for ATP production. This results in the slow progression of paralysis of extraocular muscles, which are the six muscles that control eye movement. Suffers usually experience bilateral, symmetrical progressive ptosis (drooping of the upper eye lid) then months or years later symptoms are followed up by ophthalmoparesis. This is the paralysis of the one or more of the extraocular muscles.

 

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