Intermediate Forms of CMT: A Review

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Neuromolecular Med. 2006;8(1-2):123-30.

Intermediate forms of charcot-marie-tooth neuropathy: a review.

Nicholson G, Myers S.

University of Sydney, The Molecular Medicine and ANZAC Research

Institute, Northcott Neuroscience Laboratory, Concord Hospital, NSW

2139, Australia.

The Charcot-Marie-Tooth (CMT) neuropathies divide into two main

electrophysiological groups with slow and near normal conduction

velocities corresponding to Schwann cell and axonal pathology.

An intermediate group also exists with nerve conduction velocities,

which overlaps the two main groups.

Families with intermediate CMT can be recognized in which different

affected individuals in the same family have motor conduction

velocities in both the CMT type 1 and 2 ranges (i.e., above and below

38 m/s).

The intermediate group is caused by a limited number of distinct gene

mutations in dynamin2 (DNM2), gap-junction protein 1 (GJB1),

neurofilament light polypeptide (NF-L) genes, and a rare mutation and

as yet unknown genes on chromosome 1 and 10 loci.

Intermediate forms of CMT may be associated with unique disease

mechanisms affecting both Schwann cells and axons. It is useful to

recognize this unique group of neuropathies for diagnostic and

management purposes.