Intermediate conduction velocity in two cases of Charcot-Marie-Tooth disease type 1A
Pedro José Tomaselli1, Julian Blake2,3, James M Polke4
1Clinical Hospital of Ribeirão Preto, Department of Neurosciences and Behaviour Sciences, University of São Paulo, Ribeirão Preto, Brazil.
Background And Purpose:
Charcot-Marie-Tooth disease type 1A (CMT1A) is the most prevalent hereditary neuropathy worldwide and classically has slow nerve conduction velocity (NCV), in most cases below 38 m/s. Two unrelated patients with motor NCVs in the upper limbs above 38 m/s are reported.
Method:
Case report.
Results:
Two genetically confirmed CMT1A patients are presented, from two unrelated families (one of British origin and the other of Brazilian origin). Both individuals had upper limb motor NCVs above 38 m/s, with values ranging from 41.9 to 45 m/s in the median nerve and from 42 to 42.3 m/s in the ulnar nerve. They presented with a very mild phenotype, with CMT Neuropathy Score version 2 (CMTNSv2) of 6 and 5, respectively. In contrast, affected family members within both kinships exhibited a classical phenotype with more severe disease manifestation (CMTNSv2 ranging from 12 to 20) and motor NCVs below 30 m/s.
Conclusion:
These cases, although very rare, highlight the importance of testing PMP22 duplication in patients with intermediate conduction velocities.
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