@article {449, title = {Mutations in the MORC2 gene cause axonal Charcot-Marie-Tooth disease.}, journal = {Brain}, volume = {139}, year = {2016}, month = {2016 Jan}, pages = {62-72}, abstract = {

Charcot-Marie-Tooth disease (CMT) is a complex disorder with wide genetic heterogeneity. Here we present a new axonal Charcot-Marie-Tooth disease form, associated with the gene microrchidia family CW-type zinc finger 2 (MORC2). Whole-exome sequencing in a family with autosomal dominant segregation identified the novel MORC2 p.R190W change in four patients. Further mutational screening in our axonal Charcot-Marie-Tooth disease clinical series detected two additional sporadic cases, one patient who also carried the same MORC2 p.R190W mutation and another patient that harboured a MORC2 p.S25L mutation. Genetic and in silico studies strongly supported the pathogenicity of these sequence variants. The phenotype was variable and included patients with congenital or infantile onset, as well as others whose symptoms started in the second decade. The patients with early onset developed a spinal muscular atrophy-like picture, whereas in the later onset cases, the initial symptoms were cramps, distal weakness and sensory impairment. Weakness and atrophy progressed in a random and asymmetric fashion and involved limb girdle muscles, leading to a severe incapacity in adulthood. Sensory loss was always prominent and proportional to disease severity. Electrophysiological studies were consistent with an asymmetric axonal motor and sensory neuropathy, while fasciculations and myokymia were recorded rather frequently by needle electromyography. Sural nerve biopsy revealed pronounced multifocal depletion of myelinated fibres with some regenerative clusters and occasional small onion bulbs. Morc2 is expressed in both axons and Schwann cells of mouse peripheral nerve. Different roles in biological processes have been described for MORC2. As the silencing of Charcot-Marie-Tooth disease genes have been associated with DNA damage response, it is tempting to speculate that a deregulation of this pathway may be linked to the axonal degeneration observed in MORC2 neuropathy, thus adding a new pathogenic mechanism to the long list of causes of Charcot-Marie-Tooth disease.

}, keywords = {Adult, Aged, Animals, Axons, Charcot-Marie-Tooth Disease, Female, gene expression, Humans, Infant, Male, Mice, Middle Aged, mutation, Pedigree, Phenotype, Sciatic Nerve, Sural Nerve, Transcription Factors, Young Adult}, issn = {1460-2156}, doi = {10.1093/brain/awv311}, author = {Sevilla, Teresa and Lupo, Vincenzo and Mart{\'\i}nez-Rubio, Dolores and Sancho, Paula and Sivera, Rafael and Chumillas, Mar{\'\i}a J and Garc{\'\i}a-Romero, Mar and Pascual-Pascual, Samuel I and Muelas, Nuria and Dopazo, Joaquin and V{\'\i}lchez, Juan J and Palau, Francesc and Espin{\'o}s, Carmen} } @article {456, title = {The EGR2 gene is involved in axonal Charcot-Marie-Tooth disease.}, journal = {Eur J Neurol}, volume = {22}, year = {2015}, month = {2015 Dec}, pages = {1548-55}, abstract = {

BACKGROUND AND PURPOSE: A three-generation family affected by axonal Charcot-Marie-Tooth disease (CMT) was investigated with the aim of discovering genetic defects and to further characterize the phenotype.

METHODS: The clinical, nerve conduction studies and muscle magnetic resonance images of the patients were reviewed. A whole exome sequencing was performed and the changes were investigated by genetic studies, in silico analysis and luciferase reporter assays.

RESULTS: A novel c.1226G>A change (p.R409Q) in the EGR2 gene was identified. Patients presented with a typical, late-onset axonal CMT phenotype with variable severity that was confirmed in the ancillary tests. The in silico studies showed that the residue R409 is an evolutionary conserved amino acid. The p.R409Q mutation, which is predicted as probably damaging, would alter the conformation of the protein slightly and would cause a decrease of gene expression.

CONCLUSIONS: This is the first report of an EGR2 mutation presenting as an axonal CMT phenotype with variable severity. This study broadens the phenotype of the EGR2-related neuropathies and suggests that the genetic testing of patients suffering from axonal CMT should include the EGR2 gene.

}, keywords = {Adult, Aged, Aged, 80 and over, Axons, Charcot-Marie-Tooth Disease, Early Growth Response Protein 2, Exome, Female, Humans, Male, Middle Aged, mutation, Pedigree, Phenotype, Severity of Illness Index, Young Adult}, issn = {1468-1331}, doi = {10.1111/ene.12782}, author = {Sevilla, T and Sivera, R and Mart{\'\i}nez-Rubio, D and Lupo, V and Chumillas, M J and Calpena, E and Dopazo, J and V{\'\i}lchez, J J and Palau, F and Espin{\'o}s, C} }