Motor neurone disease

 

Clinical features

  1. Motor neurone disease is also known as amyotrophic lateral sclerosis (ALS) or Lou Gehrig disease.
  2. It is a rapidly advancing condition characterised by progressive muscle weakness due to the death of motor neurons in the brain, brain stem and spinal cord.
  3. This affects movement of the limbs, speech, swallowing and respiration.
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Genetics

  1. Inherited motor neurone disease shows:
  2. Familial aggregation
  3. An earlier age of onset than average (40s or younger)
  4. Clinical features essentially the same as the sporadic form
  5. Approximately 10% of cases of motor neurone disease are thought to be due to mutations in a single gene.
  6. About 20% of cases all inherited motor neurone disease is due to mutations in the SOD1 gene
  7. In these cases, the inheritance pattern is autosomal dominant
  8. However, some causative mutations in SOD1 are not fully penetrant so the person may remain
    asymptomatic despite having the mutation
  9. Other genes in which mutations can cause motor neurone disease include:
  10. ALS2 which follows a pattern of autosomal recessive inheritance
  11. ALS4 which follows a pattern of autosomal dominant inheritance and is associated with variations in the SETX gene
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Investigations

  1. Diagnostic and predictive genetic testing if appropriate may be available through a neurogenetics service
    or Genetics Services.
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Management

  1. Consider referral to a neurogenetics service or Genetics Services where:
  2. More than one member of a family has motor neurone disease
  3. A sporadic case has an early age of onset
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