CMT Diagnostic value of ultrastructural nerve examination

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Acta Neuropathol (Berl). 2007 Feb 10

Diagnostic value of ultrastructural nerve examination in Charcot-

Marie-Tooth disease: two CMT 1B cases with pseudo-recessive

inheritance.

Vallat JM, Magy L, Lagrange E, Sturtz F, Magdelaine C, Grid D, Tazir

M.

Department of Neurology et Centre National de Reference des

Neuropathies Peripheriques Rares, University Hospital, 2 Avenue

Luther King, 87042, Limoges Cedex, France

We report two sporadic patients of CMT disease in different

consanguineous families. The electrophysiological examination led to

the diagnosis of a severe demyelinating neuropathy. The nerve

biopsies exhibited numerous outfoldings of the myelin sheaths and

onion-bulb proliferations. The consanguinity and the histological

findings pointed to a diagnosis of CMT 4B.

However, the detection of abnormal and regular widenings between the

major dense lines of the myelin lamellae by electron microscopy led

us to search for a P0 gene mutation. Two heterozygous mutations of

this gene were identified: S63F and N131Y. Different aspects of

uncompacted myelin lamellae have been described in some cases of P0

mutations and a few now appear to be quite specific to it. More than

30 genes are implicated in CMT and as mutation search is time- and

money-consuming, we believe that in some selected patients

ultrastructural examination of nerves, among other criteria, helps

orientate the molecular diagnosis of CMT.