The shifting paradigm of Charcot-Marie-Tooth disease.

Molecular studies have created a paradigm shift in our perception of Charcot-Marie-Tooth disease (CMT). Indeed, CMT has evolved from the concept of a rather homogeneous hereditary disease exclusively involving peripheral nerves to the concept of a highly heterogeneous clinical and genetic syndrome mainly - but sometimes not exclusively - involving the peripheral nervous system. The phenotypic spectrum of CMT overlaps with other inherited neuropathies such as distal hereditary motor neuropathy (dHMN), hereditary sensory and autonomic neuropathy (HSAN), spinal muscular atrophy (SMA) subtypes, and the neuropathies of mitochondrial disorders. At a molecular level, mutations in one given gene may alternatively provoke CMT, HSAN, dHMN or SMA variants. Over the last years, there have been dramatic advances in deciphering the molecular basis for many CMT subtypes and more than 900 different mutations in more than 60 causative genes are now described. However, as 75% of CMT causative genes apparently remain unknown and as disease-specific therapies are not available, major advances are yet to come in the field of CMT.

[Research in amyotrophic lateral sclerosis: what is new in 2009?]. / La recherche sur la SLA en 2009 : compte rendu du groupe bibliographique de la coordination des centres SLA.

This paper, written by French amyotrophic lateral sclerosis (ALS) center experts, presents an update of recent advances in fundamental, epidemiological and clinical research in ALS based on a review of the literature between September 2008 and November 2009. Among other pathophysiological mechanisms, the role of stress of the endoplasmic reticulum and the importance of energetic metabolic disturbances have been underscored. In the field of genetics, research has been advanced through the identification of mutations of the gene FUsed in Sarcoma/Translated in LipoSarcoma (FUS/TLS) in individuals with familial and sporadic ALS. This gene is involved in the regulation of transcription, splicing and RNA transport, and has functional homology to another ALS gene, TARDBP, which suggests that a common mechanism may underlie motor neuron degeneration. A report showed that mice expressing a mutant form of human TDP-43 develop a progressive and fatal neurodegenerative disease reminiscent of both ALS and frontotemporal lobar degeneration with ubiquitin aggregates (FTLD-U), providing a new animal model that may help to better understand the pathophysiology and test new therapeutics. Beside genetic studies, several epidemiologic studies have investigated the role of environmental factors. A recent study suggests that smoking is a risk factor for developing ALS and it is hypothesized that this could occur through lipid peroxidation via formaldehyde exposure. From a neuroprotective perspective, trials with IGF-1, sodium valproate, coenzyme Q or glatiramer acetate have failed to demonstrate any beneficial effect. A study published in 2008 argued that lithium may have a neuroprotective effect in ALS mice and also in patients. However, two preclinical studies failed to replicate the neuroprotective effect of lithium in ALS mice. Therapeutic trials have been performed or are currently ongoing in Europe and North America. Their results have not yet been published.