Type 1B and nerve biopsy - from France

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Abstract from Ultrastruct Pathol 2003 Jan-Feb;27(1):1-5

Uncompacted myelin lamellae in peripheral nerve biopsy.

Vital C, Vital A, Bouillot S, Favereaux A, Lagueny A, Ferrer X,

Brechenmacher C, Petry KG.

Neuropathology Laboratory and Neurobiologie des affections de la

myeline, EA2966, Victor Segalen University, Bordeaux, France.

Since 1979, the authors have studied 49 peripheral nerve biopsies

presenting uncompacted myelin lamellae (UML). Based on the

ultrastructural pattern of UML they propose a 3-category classification.

The first category includes cases displaying regular UML, which was

observed in 43 cases; it was more frequent in 9 cases with

polyneuropathy organomegaly endocrinopathy m-protein skin changes

(POEMS) syndrome as well as in 1 case of Charcot-Marie-Tooth 1B with a

novel point mutation in the P0 gene. The second category consists of

cases showing irregular UML, observed in 4 cases with IgM monoclonal

gammopathy and anti-myelin-associated glycoprotein (MAG)

activity. This group included 1 benign case and 3 B-cell malignant

lymphomas.The third category is complex UML, which was present in 2

unrelated patients with an Arg 98 His missense mutation in the P0

protein gene. Irregular and complex UML are respectively related to MAG

and P0, which play a crucial role in myelin lamellae compaction

and adhesion.