Hereditary neuropathies: An update.

Hereditary neuropathies are the most common inherited neuromuscular diseases. Charcot-Marie-Tooth (CMT) disease represents the most common form with an average prevalence ranging from 1/2500 to 1/1200, depending on the studies. To date and with the advances of the latest generation sequencing, more than 80 genes have been identified. Although the common clinical phenotype comprises a progressive distal muscle weakness and sensory loss, foot deformities and decreased or absent tendon reflexes, clinical and electrophysiological phenotypes exhibit great variability. Moreover, atypical phenotypes are arising, overlapping with spastic paraplegia, hereditary sensory neuropathies or amyotrophic lateral sclerosis. The causative genes are involved in various biological processes such as myelin development and maintenance, biosynthesis and degradation of proteins, neuronal structural maintenance, axonal transport, endocytosis, membrane dynamics, ion-channel function and the mitochondrial network. An accurate genetic diagnosis is important for appropriate genetic counselling and treatment options. Therapeutic advances, particularly small interfering RNA therapy, are encouraging in hereditary transthyretin amyloid neuropathy.