The homozygous ganglioside-induced differentiation-associated protein 1 mutation c.373C > T causes a very early-onset neuropathy: case report and literature review

GDAP1 mutations are frequent among Brazilian patients with autosomal recessive axonal Charcot-Marie-Tooth disease

Mutations in ganglioside-induced differentiation-associated-protein 1 (GDAP1) are associated with several subtypes of Charcot-Marie-Tooth (CMT) disease, including autosomal recessive and demyelinating (CMT4A); autosomal recessive and axonal (AR-CMT2K); autosomal dominant and axonal (CMT2K); and an intermediate and recessive form (CMTRIA). To date, at least 103 mutations in this gene have been described, but the relative frequency of GDAP1 mutations in the Brazilian CMT population is unknown. In this study, we investigated the frequency of GDAP1 mutations in a cohort of 100 unrelated Brazilian CMT patients. We identified five variants in unrelated axonal CMT patients, among which two were novel and probably pathogenic (N64S, P119T) one was novel and was classified as VUS (K207L) and two were known pathogenic variants (R125* and Q163*). The prevalence rate of GDAP1 among the axonal CMT cases was 7,14% (5/70), all of them of recessive inheritance, thus suggesting that the prevalence was higher than what is observed in most countries. All patients exhibited severe early-onset CMT that was rapidly progressive. Additionally, this study widens the mutational spectrum of GDAP1-related CMT through identification of two novel likely pathogenic variants.

Impaired Mitochondrial Mobility in Charcot-Marie-Tooth Disease

Charcot-Marie-Tooth (CMT) disease is a progressive, peripheral neuropathy and the most commonly inherited neurological disorder. Clinical manifestations of CMT mutations are typically limited to peripheral neurons, the longest cells in the body. Currently, mutations in at least 80 different genes are associated with CMT and new mutations are regularly being discovered. A large portion of the proteins mutated in axonal CMT have documented roles in mitochondrial mobility, suggesting that organelle trafficking defects may be a common underlying disease mechanism. This review will focus on the potential role of altered mitochondrial mobility in the pathogenesis of axonal CMT, highlighting the conceptional challenges and potential experimental and therapeutic opportunities presented by this "impaired mobility" model of the disease.

Peripheral neuropathy and gastroenterologic disorders: an overview on an underrecognized association

BACKGROUND AND AIM OF THE WORK

Although peripheral neuropathies in children are often of genetic origin, acquired causes should be carefully looked for and ruled out also in the pediatric age. Gastroenterological disorders can be complicated by peripheral neuropathy as a result of micronutrients deficiency, drug toxicity or because of shared pathophysiological mechanisms.

METHODS

In this descriptive review we sought to give an overview on the most relevant clinical conditions in which peripheral neuropathies are associated with gastro-intestinal disorders or symptoms.

RESULTS

We describe the clinical, demographic, and electrophysiological features of peripheral neuropathy in three main clinical scenarios: in the context of common gastroenterological disorders (inflammatory bowel and celiac disease), in the context of micronutrients deficiencies arising from malabsorption irrespective of etiology, and in a rare degenerative mitochondrial disorder, mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) disorder.

CONCLUSIONS

The association between gastrointestinal and peripheral nervous system symptoms is probably still underrecognized but has to be actively sought, in order to provide prompt diagnosis resulting in optimal care and long-term management with the aim to improve quality of life and, at least in some conditions, try to impact on prognosis.