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La atrofia muscular espinal y bulbar es una enfermedad neurologica caracterizada por degeneracion gradual de la motoneurona inferior, que resulta en debilidad muscular, atrofia y fasciculaciones. Es una entidad de etiologia genetica con mecanismo de herencia ligado al cromosoma X recesivo, por lo que afecta a varones, en la que se produce una expansion del triplete CAGn en el gen del receptor de androgenos. Se manifiesta por signos de insensibilidad a los androgenos (ginecomastia e infertilidad). A partir de los 20-30 anos, aproximadamente, comienzan los signos de afectacion de la motoneurona inferior a nivel espinal con calambres y temblor de accion y posteriormente debilidad muscular. En la evolucion se evidencia compromiso bulbar. Se presenta el caso clinico-genealogico de un varon de 32 anos con temblores en quien se confirma molecularmente la enfermedad de Kennedy. Este es el primer caso, hasta nuestro conocimiento, reportado en Uruguay. Se destaca la importancia de plantear dicha afeccion en un paciente joven con “temblores” cuando aun no es ostensible la debilidad muscular. La historia familiar es de capital importancia. La presencia de fasciculaciones en el estudio electrico a nivel perioral es muy sugestiva de esta patologia. La confirmacion molecular es importante para el asesoramiento genetico.

Currently more than 30 genes are known to be responsible for genetically determined neuropathies. Charcot-Marie-Tooth (CMT) disease is the most frequent of these hereditary neuropathies, with a prevalence of 4.7 to 36 per 100 000. In its demyelinating forms (CMT1), approximately 70% of cases are associated with a duplication of the PMP22gene. In its axonal forms (CMT2), 10-20% of the cases may be associated with a mutation of the MFN2gene. For North African patients with recessive transmission, a mutation of the LMNA gene must be sought. It is essential to stress the great variability of the phenotype--clinical, electrophysiological, and histologic--between and within families. A detailed analysis of these criteria, together with consideration of ethnic origin, may guide the search for the causal mutation. Whether the case involves certainly hereditary transmission or a sporadic form, it is desirable to be able to examine the maximum number of the patient's kin, both clinically and electrophysiologically. The forms with recessive transmission usually have a very early onset and are more serious than the dominant forms. The early- and very early-onset forms of CMT are increasingly better distinguished: congenital hypomyelination neuropathy (mutations of PMP22, MPZ or EGR2), or more axonal forms, including SMARD1 (Spinal muscle atrophy with respiratory distress; mutations of IGHMBP2) and EOHMSN (Early-onset hereditary motor and sensory neuropathy; mutations of MFN2). The prevention of cutaneous (ulcerations), bone, and amputation complications is very important in patients with hereditary sensory and autonomic neuropathies, because of the severity of the sensory disorders.

International audience; There are several pathogenic mechanisms of peripheral nerve involvement in patients with monoclonal dysglobulinemia. Intranervous proliferation of malignant cells, immunoglobulin, or amyloid deposits in the endoneurial space can only be determined by examination of nerve biopsy specimens. We present clinical, electrophysiological, and histological data from seven patients whose polyneuropathy was induced by immunoglobulin deposits in the endoneurial space. As these lesions cannot be demonstrated on clinical and electrophysiological grounds, the indication for nerve biopsy derives from careful analysis of each patient presenting with a polyneuropathy and a monoclonal dysglobulinemia. To visualize and clearly characterize these deposits, electron microscopic examination is indispensable. Immunocytochemical methods using both light and electron microscopy for ultrastructural analysis are of great value. Demonstration of endoneurial immunoglobulin deposits may have major therapeutic consequences. Indeed, identification of these deposits prompted the use of aggressive treatment, which was quite effective in five of our seven patients.

International audience; Background: Mutations in the gene encoding mito- fusin 2 (MFN2) cause Charcot-Marie-Tooth disease type 2 (CMT2), with heterogeneity concerning severity and associated clinical features. Objective: To describe MFN2 mutations and associ- ated phenotypes in patients with hereditary motor and sensory neuropathy (HMSN). Design: Direct sequencing of the MFN2 gene and clini- cal investigations of patients with MFN2 mutations. Setting: Molecular genetics laboratory of a university hospital and the LimogesNational Referral Center for Rare Peripheral Neuropathies. Patients: One hundred fifty index patients with HMSN and amedianmotor nerve conduction velocity of 25m/s or greater and without mutations in the genes encoding connexin 32 and myelin protein zero. Main Outcome Measures: Results of genetic analy- ses and phenotypic observations. Results: Twenty different missense mutations were identified in 20 index patients. Mutation frequency was 19 of 107 (17.8%) in patients with CMT2 and 1 of 43 (2.3%) in patients with a median motor nerve conduc- tion velocity less than 38 m/s. Four patients had proven de novo mutations, 8 families had autosomal dominant inheritance, and 3 had autosomal recessive inheritance. The remaining 5 patients were sporadic cases with het- erozygous mutations. Phenotypes varied from mild forms to early-onset severe forms. Additional features were encountered in 8 patients (32%). Six patients un- derwent sural nerve biopsy: electronic microscopy showed prominent mitochondrial abnormalities on longitudinal sections. Conclusions: MFN2 mutations are a frequent cause of CMT2, with variable severity and either dominant or recessive inheritance. MFN2 gene testing must be a first-line analysis in axonal HMSN irrespective of the mode of inheritance or the severity of the peripheral neuropathy.

Although there are many human hereditary neuropathies, most of them with the exception of Charcot-Marie-Tooth disease or hereditary sensorimotor neuropathy, are rare. Irrespective of their type, the mode of transmission may be autosomal dominant or recessive, or X-linked. The most difficult to diagnose, however, are the sporadic forms. It is customary to distinguish the cases in which the neuropathy is the sole clinical expression from multisystemic diseases where neuropathy is one component of multi-organ involvement. The complexity and the multiplicity of genes involved and the lack of understanding of their exact functions hinder logical presentation of these hereditary neuropathies. For understandable technical reasons, the stage of specific treatment, namely the repair of the mutated gene, has yet to be attained.