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last update : 22-01-2019
Symbol SMALED2
Location 9q22
Name extremity-predominant spinal muscular atrophy-2
Corresponding gene BICD2
Main clinical features
  • spinal muscular atrophy characterized by early-childhood onset of muscle weakness and atrophy predominantly affecting the proximal and distal muscles of the lower extremity, although some patients may show upper extremity involvement
  • delayed walking, waddling gait, difficulty walking, and loss of distal reflexes
  • congenital slowly progressive dominant SMA
  • also severe form of congenital muscular atrophy with arthrogryposis multiplex, respiratory insufficiency and lethality within four months (PMID: 28635954))
  • Genetic determination autosomal dominant
    Function/system disorder neurology
    Type disease
  • perturbation of BICD2-mediated trafficking of RAB6-positive secretory vesicles leads to impaired development and maintenance of a key subset of anterior horn cells and upper motor neurons and thus results in both the static and the slowly progressive features that characterize BICD2-associated disorders (PMID: 23664120))
  • BICD2 mutations increase microtubule stability in motor neurons leading to increased axonal branching and to impaired neuromuscular junction development (PMID: 29528393))