title: Strategy for genetic testing in Charcot-Marie-disease.
abstract: BACKGROUND
  Charcot Marie Tooth disease (CMT) affects one in 2500 people. Genetic testing is often pursued for family planning purposes, natural history studies and for entry into clinical trials. However, identifying the genetic cause of CMT can be expensive and confusing to patients and physicians due to locus heterogeneity.
  
  
  METHODS
  We analyzed data from more than 1000 of our patients to identify distinguishing features in various subtypes of CMT. Data from clinical phenotypes, neurophysiology, family history, and prevalence was combined to create algorithms that can be used to direct genetic testing for patients with CMT.
  
  
  RESULTS
  The largest group of patients in our clinic have slow motor nerve conduction velocities (MNCV) in the upper extremities. Approximately 88% of patients in this group have CMT1A. Those who had intermediate MNCV had primarily CMT1X (52.8%) or CMT1B (27.8%). Patients with very slow MNCV and delayed walking were very likely to have CMT1A (68%) or CMT1B (32%). No patients with CMT1B and very slow MNCV walked before 15 months of age. Patients with CMT2A form our largest group of patients with axonal forms of CMT.
  
  
  CONCLUSIONS
  Combining features of the phenotypic and physiology groups allowed us to identify patients who were highly likely to have specific subtypes of CMT. Based on these results, we created a series of algorithms to guide testing. A more detailed review of this data is published in Annals of Neurology (1).
authors: Department of Neurology Wayne State University School of Medicine, 421 Ea Canfield, Elliman 3217, Detroit, MI 48201, USA.
authors: L J
authors: LJ
authors: Miller
authors: A S D
authors: AS
authors: Saporta
authors: S L
authors: SL
authors: Sottile
authors: C E
authors: CE
authors: Siskind
authors: S M E
authors: SM
authors: Feely
authors: M E
authors: ME
authors: Shy
mesh_terms: D017668:Age of Onset; D000465:Algorithms; D019090:Case Management / Q000458:organization & administration*; D002607:Charcot-Marie-Tooth Disease / Q000175:diagnosis* / Q000453:epidemiology / Q000235:genetics* / Q000503:physiopathology; D004568:Electrodiagnosis; D005820:Genetic Testing / Q000379:methods* / Q000592:standards / Q000706:statistics & numerical data; D006801:Humans; D040582:Inheritance Patterns; D009046:Motor Neurons / Q000473:pathology; D009431:Neural Conduction; D018579:Patient Selection; D010375:Pedigree; D017410:Practice Guidelines as Topic / Q000592:standards; D015995:Prevalence; D012720:Severity of Illness Index; D034941:Upper Extremity / Q000294:innervation / Q000503:physiopathology