Spinal Muscular Atrophy: Test and Diagnosis

1st order laboratory parameters – obligatory laboratory tests.

  • Molecular genetic testing – analysis for mutations in the SMN1 gene on chromosome 5.
  • Muscle biopsy (an incision about 7.5 cm long and removal of part of the muscle tissue from the thigh) – if atrophy of type 1 (faster twitching) and type 2 (slow twitching) muscle fibers is found, this gives high evidence of spinal muscular atrophy.

Laboratory parameters 2nd order – depending on the results of the history, physical examination, etc. – for differential diagnostic clarification.

  • Creatine kinase (CPK – due todifferential diagnosis: if elevated, is possibly other neurodegenerative diseases [muscular dystrophy Duchenne: 10-100-fold increased].
  • Molecular genetic testing
    • Gene EMD for the protein emerin on chromosome X (due toEmery-Dreifuss muscular dystrophy).
    • Gene SMCDH1 and other genes of chromosome 18 related to facio-scapulo-humeral muscular dystrophy (FSHD) of various genes related to limb-girdle dystrophy.
    • AR gene of the X chromosome (due tospinobulbar muscular atrophy type Kennedy).
    • ISPD gene on chromosome 12 (due toWalker-Warburg syndrome).
    • POMGNT1 gene on chromosome 1 (due tomuscle-eye-brain disease).
  • HIV test – due topossible differential diagnosis in neuromuscular and myopathic complications of HIV.