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Phenotypic variability in siblings with type III spinal muscular atrophy
  1. M M K Muqit4,
  2. J Moss2,
  3. C Sewry3,
  4. R J M Lane1
  1. 1Division of Clinical Neurosciences and Psychological Medicine, Imperial College at Charing Cross Hospital, London W6, UK
  2. 2Division of Pathology, Imperial College at Charing Cross Hospital
  3. 3Dubowitz Neuromuscular Unit, Imperial College at Hammersmith Hospital, London W12
  4. 4Department of Molecular Pathogenesis, Institute of Neurology, National Hospital for Neurology and Neurosurgery, Queen Square, London WC1
  1. Correspondence to:
 Dr Russell J M Lane
 West London Neurosciences Centre, Charing Cross Hospital, Fulham Palace Road, London W6 8RF, UK;


Autosomal recessive spinal muscular atrophy (SMA) shows substantial phenotypic variability, presenting at a variety of ages from infancy to adult life. Diagnostic difficulties may arise because SMA sometimes produces a dystrophic or myopathic phenotype rather than classical neurogenic abnormalities. Two brothers are described who illustrate this principle and highlight the increasing importance of molecular genetics in investigating patients with neuromuscular diseases. The findings are discussed in the light of recent observations in a mouse model of SMA.

  • SMA, spinal muscular atrophy
  • SMN, survival motor neurone
  • genetics
  • myopathy
  • spinal muscular atrophy

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  • Competing interests: none declared