Distal hereditary motor neuropathies.

Distal hereditary motor neuropathies (dHMN) are a group of heterogeneous hereditary disorders characterized by a slowly progressive distal pure motor neuropathy. Electrophysiology, with normal motor and sensory conduction velocities, can suggest the diagnosis of dHMN and guide the genetic study. More than thirty genes are currently associated with HMNs, but around 60 to 70% of cases of dHMN remain uncharacterized genetically.

[The high phenotypic variability of RYR1 gene mutations].

The RYR1 gene encodes the ryanodine-receptor 1, a key protein in the excitation-contraction coupling that takes place in muscle fibers. This receptor is the main channel responsible for calcium release from the endoplasmic reticulum [1]. A number of clinical phenotypes are linked to various mutations in this large gene as shown in a compilation established by ORPHANET (see table).

A TOR1AIP1 variant segregating with an early onset limb girdle myasthenia-Support for the role of LAP1 in NMJ function and disease.

Rare pathogenic variants in TOR1AIP1 (OMIM 614512), coding the inner nuclear membrane protein lamin-associated protein 1 (LAP1), have been associated with a spectrum of disorders including limb girdle muscular dystrophy with cardiac involvement and a severe multisystem phenotype. Recently, Cossins et al reported two siblings with limb girdle muscular dystrophy and impaired transmission of the neuromuscular synapse, demonstrating that defective LAP1 may lead to a congenital myasthenic syndrome. Herein, we describe the association of TOR1AIP1 deficiency with congenital myasthenic syndrome in three siblings.

Nerve Biopsy Is Still Useful in Some Inherited Neuropathies.

In hereditary neuropathies, next-generation sequencing techniques are producing a vast number of candidate gene mutations that need to be verified or excluded by careful genotype-phenotype correlation analysis. In most cases, clinical acumen is still important but needs to be combined with data from nerve conduction studies and, in some cases, from nerve biopsy examinations. Indeed, characteristic clinical, electrophysiological, and sometimes pathological features may be suggestive of a particular subtype of Charcot-Marie-Tooth (CMT) disease.

Arginine:glycine amidinotransferase (AGAT) deficiency: Clinical features and long term outcomes in 16 patients diagnosed worldwide.

Background: Arginine:glycine aminotransferase (AGAT) (GATM) deficiency is an autosomal recessive inborn error of creative synthesis.

Objective: We performed an international survey among physicians known to treat patients with AGAT deficiency, to assess clinical characteristics and long-term outcomes of this ultra-rare condition.

Results: 16 patients from 8 families of 8 different ethnic backgrounds were included.

Hereditary motor and sensory neuropathies or Charcot-Marie-Tooth diseases: an update.

Hereditary motor and sensory neuropathies (HMSN) or Charcot-Marie-Tooth (CMT) diseases are the most common degenerative disorders of the peripheral nervous system. However, the frequency of the different subtypes varies within distinct populations. Although more than seventy clinical and genetic forms are known to date, more than 80% of CMT patients in Western countries have genetic abnormalities associated with PMP22, MPZ, MFN2 and GJB1.

Autosomal recessive Charcot-Marie-Tooth disease: from genes to phenotypes.

The prevalence of Charcot-Marie-Tooth (CMT) disease or hereditary motor and sensory neuropathy (HMSN) varies in different populations. While in some countries of Western Europe, the United States and Japan the dominant form of HMSN is the most frequent, in other countries such as those of the Mediterranean Basin, the autosomal recessive form (AR-CMT) is more common. Autosomal recessive CMT cases are generally characterized by earlier onset, usually before the age of 2 or 3 years, and rapid clinical progression that results in severe polyneuropathy and more marked distal limb deformities such as pes equino-varus, claw-like hands, and often major spinal deformities.

Multicenter transversal two-phase study to determine a national prevalence of epilepsy in Algeria.

Background/aims: The prevalence of epilepsy in Algeria is unknown. The aims of this multicenter transversal study were to determine the national prevalence and clinical characteristics of epilepsy in the Algerian population.

Methods: This two-phase study was conducted in 5 circumscriptions and included 8,046 subjects aged over 2 months who attended the randomly selected public and private primary care clinics.

Novel mutations in the PRX and the MTMR2 genes are responsible for unusual Charcot-Marie-Tooth disease phenotypes.

Autosomal recessive Charcot-Marie-Tooth diseases, relatively common in Algeria due to high prevalence of consanguineous marriages, are clinically and genetically heterogeneous. We report on two consanguineous families with demyelinating autosomal recessive Charcot-Marie-Tooth disease (CMT4) associated with novel homozygous mutations in the MTMR2 gene, c.331dupA (p.

Phenotypic variability in giant axonal neuropathy.

Giant axonal neuropathy (GAN), a severe childhood disorder affecting both the peripheral nerves and the central nervous system, is due to mutations in the GAN gene encoding gigaxonin, a protein implicated in the cytoskeletal functions and dynamics. In the majority of the GAN series reported to date, patients had the classical clinical phenotype characterized by a severe axonal neuropathy with kinky hair and early onset CNS involvement including cerebellar and pyramidal signs. We present 12 patients (6 families) with GAN mutations and different clinical phenotypes.