I read with interest the excellent review on Charcot-Marie-Tooth disease (CMT) by Reilly and Shy (1). I wish to make a brief comment on CMT associated with dynamin 2 gene mutations. This CMT subtype is currently classified within dominant intermediate CMT type B (DI-CMTB), as electrophysiological study characteristically shows motor conduction velocities in the intermediate range (25-45 m/s). There are, however, three recent pedigrees associated to mutations in the PH or M domain of the gene causing a well defined axonal phenotype (2-4). CMT subtypes (CMT1, CMT2A, etc.) are used to characterise specific causes of each of the larger categories (1). As demonstrated in the case of several CMT causative gene mutations, including dynamin 2, this system is not perfect (1). CMT caused by dynamin 2 mutations could be classified either within DI-CMTB, or within CMT2 in which case this calls for a new acronym (following the order of publication this might be CMT2M).

References 1. Reilly MM, Shy ME. Diagnosis and new treatments in genetic neuropathies. J Neurol Neurosurg Psychiatry 2009; 80: 1304-14. 2. Fabrizi GM, Ferrarini M, Cavallaro T, et al. Two novel mutations in dynamin-2 cause axonal Charcot-Marie-Tooth disease. Neurology 2007; 69: 291-5. 3. Gallardo E, Claeys KG, Nelis E, et al. Magnetic resonance imaging findings of leg musculature in Charcot-Marie-Tooth disease type 2 due to dynamin 2 mutation. J Neurol 2008; 255:986-92. 4. Claeys KG, Zuchner S, Kennerson M, et al. Phenotypic spectrum of dynamin 2 mutations in Charcot-Marie-Tooth neuropathy. Brain 2009; 132: 1741-52.

Conflict of Interest:

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