Charcot-Marie-Tooth disease type 1A, 9 November 1992, San Francisco, CA, U.S.A

Charcot-Marie-Tooth 1A: A narrative review with clinical and anatomical perspectives

Charcot-Marie-Tooth 1A (CMT1A) is regarded as the most common hereditary peripheral neurodegenerative disorder. This narrative review highlights perspectives around the historically well-established and characteristic anatomical manifestations of CMT1A seen in the feet, legs and hands, in addition to a clinical diagnosis that may be confirmed by electrophysiology, genetic or molecular markers together with the presence of a typical family history. A less well-known perspective is the potential for systemic manifestations and wider complication. The condition is characterised by a progressive clinical picture with unmistakable anatomical and neurological features that have been described since the late 19th century. There remains no cure although supportive, rehabilitative, and surgical regimes may provide helpful management or amelioration of symptoms. Most recently, the emergence of a pleotherapeutic approach suggests distinct promise. Future research focused on a detailed elucidation of the underlying molecular mechanisms underpinning myelin and axonal function may eventually hold the key to successful treatment of CMT1A. Genetic modification would potentially present a cure. Clin. Anat. 29:547-554, 2016. © 2015 Wiley Periodicals, Inc.

Improved culture methods to expand Schwann cells with altered growth behaviour from CMT1A patients

A duplication of the gene for myelin protein PMP22 is by far the most common cause of the hereditary demyelinating neuropathy CMT1A. A role for PMP22 in cell growth in addition to its function as a myelin protein has been suggested because PMP22 is homologous to a gene specifically upregulated during growth arrest. Furthermore, transfected rat Schwann cells overexpressing PMP22 show reduced growth. In addition, abnormal Schwann cell differentiation has been described in nerve biopsies from CMT1A patients. To analyse whether the duplication of the PMP22 gene in CMT1A neuropathy primarily alters Schwann cell differentiation and to exclude nonspecific secondary responses, we improved human Schwann cell culturing. This allowed us long-term passaging of human Schwann cells with unchanged phenotype, assessed by expression of different Schwann cell markers. Subsequently we established Schwann cell cultures from CMT1A nerve biopsies. We find decreased proliferation of Schwann cells from different CMT1A patients in all passages. We also demonstrate PMP22 mRNA overexpression in cultured CMT1A Schwann cells. We conclude that decreased proliferation in cultured Schwann cells that carry the CMT1A duplication indicates abnormal differentiation of CMT1A Schwann cells. The identification of an abnormal phenotype of CMT1A Schwann cells in culture could possibly lead to an in vitro disease model.