Genetic and clinical spectrum of early growth response 2-related Charcot-Marie-Tooth disease in a Brazilian cohort

BACKGROUND

 Charcot-Marie-Tooth (CMT) disease is a genetically diverse group of hereditary neuropathies. Most studies on the frequency of CMT subtypes report that the early growth response 2 (EGR2) gene accounts for less than 1% of cases. However, data regarding the epidemiology and clinical characteristics of EGR2-related CMT in Central and South America remain limited.

OBJECTIVE

 To characterize the clinical and genetic features of EGR2-related CMT in a Brazilian cohort.

METHODS

 We retrospectively analyzed clinical and ancillary data from four individuals with confirmed molecular diagnosis of EGR2-related CMT. Patients were categorized based on age of onset, motor nerve conduction velocity of the ulnar nerve, and nerve biopsy findings when available. Next-generation sequencing was utilized for genetic analysis.

RESULTS

 Pathogenic and likely pathogenic variants were identified exclusively in the three zinc-finger domains of EGR2, including a novel variant, c.1234G > C (p.Glu412Gln). Patients exhibited significant variation in clinical severity and phenotypes. Dysphagia, respiratory complications, and scoliosis were prominent features.

CONCLUSION

 Our findings corroborate the complex and varied clinical presentations of EGR2-related CMT, highlighting respiratory issues and dysphagia as significant features. Comprehensive clinical assessment and early genetic diagnosis are essential for managing this condition's diverse phenotypic spectrum.

Review of general and head and neck/oral and maxillofacial features of Charcot-Marie-Tooth disease and dental management considerations

Charcot-Marie-Tooth disease (CMTD) is an uncommon progressive neuromuscular disorder of the peripheral nervous system and primarily leads to distal extremity weakness and sensory deficits. Frequently, affected patients manifest pes cavus, drop foot, and digit contractures that may pose significant challenges in ambulation and grasping objects. Although there are numerous articles of this syndrome in the medical literature, there is a limited number of dental publications. The objective of this article is to review the general and head and neck/oral and maxillofacial features of CMTD. General guidelines for dental management are also provided.

Screening for oropharyngeal dysphagia in adult patients with neuromuscular diseases using the Sydney Swallow Questionnaire

INTRODUCTION/AIMS

Oropharyngeal dysphagia is common in patients with neuromuscular diseases (NMDs). Its early recognition is vital for proper management. We tested a large cohort of adult NMD patients for oropharyngeal dysphagia using the Sydney Swallow Questionnaire (SSQ). We also looked for possible differences in characteristics of oropharyngeal dysphagia in various NMD groups and diseases. Finally, we compared results of this screening with those from their corresponding medical records for eventual "clinical history" of dysphagia.

METHODS

We asked patients to fill in the SSQ during follow-up outpatient visits at our neuromuscular reference center. A total score above the cutoff score of 118.5 out of 1700 was indicative of oropharyngeal dysphagia.

RESULTS

Of the 304 adult patients assessed for eligibility, 201 NMD patients (96 women and 105 men, aged 49.0 ± 16.2 years) were included and tested in this study. Oropharyngeal dysphagia was detected in 45% of all the NMD patients when using the SSQ, whereas only 12% had a positive medical record for dysphagia. The median SSQ scores for patients with myotonic syndromes (including myotonic dystrophy type 1), with amyotrophic lateral sclerosis, and with facioscapulohumeral dystrophy were above the cutoff score. The SSQ scores obtained revealed distinct oropharyngeal dysphagia characteristics in the different NMD groups and diseases.

DISCUSSION

The SSQ tests positively for oropharyngeal dysphagia in a higher proportion of NMD patients compared with their medical records. The distinct oropharyngeal dysphagia characteristics we revealed in different NMD groups and diseases may help to elaborate adapted clinical approaches in the management of oropharyngeal dysphagia.

Vocal cord paralysis in Charcot-Marie-Tooth type 4b1 disease associated with a novel mutation in the myotubularin-related protein 2 gene: A case report and review of the literature

•

Vocal cord paralysis is a relevant symptom of Charcot–Marie–Tooth type 4B1.

•

Patients harboring MTMR2 mutations should be investigated for laryngeal function.

•

A new mutation in the MTMR2 gene is described.

•

The frequency of vocal cord paralysis in early-onset CMT subtypes is explored.

Charcot–Marie–Tooth type 4B1 (CMT4B1) is an autosomal recessive motor and sensory demyelinating neuropathy characterized by the association of early-onset neurological symptoms and typical histological findings. The natural history and the clinical variability of the disease are still poorly known, thus further clarification of the different phenotypes is needed. We report on the case of a Pakistani girl born to consanguineous parents harboring a novel mutation in the MTMR2 gene. When aged 18 months, reduced limb tone, muscle wasting associated with proximal and distal weakness prevalent in lower limbs, absence of tendon reflexes, hoarseness and inspiratory stridor were detected. Vocal cord palsy was diagnosed shortly after. We suggest that laryngeal involvement might be a relevant and initial feature of early-onset CMT4B1 neuropathy. Thus, affected patients should undergo early laryngological evaluation in order to prompt an appropriate management.

Management of Charcot-Marie-Tooth disease: improving long-term care with a multidisciplinary approach

Charcot–Marie–Tooth (CMT) disease is the most common inherited neuropathy and one of the most common inherited diseases in humans. The diagnosis of CMT is traditionally made by the neurologic specialist, yet the optimal management of CMT patients includes genetic counselors, physical and occupational therapists, physiatrists, orthotists, mental health providers, and community resources. Rapidly developing genetic discoveries and novel gene discovery techniques continue to add a growing number of genetic subtypes of CMT. The first large clinical natural history and therapeutic trials have added to our knowledge of each CMT subtype and revealed how CMT impacts patient quality of life. In this review, we discuss several important trends in CMT research factors that will require a collaborative multidisciplinary approach. These include the development of large multicenter patient registries, standardized clinical instruments to assess disease progression and disability, and increasing recognition and use of patient-reported outcome measures. These developments will continue to guide strategies in long-term multidisciplinary efforts to maintain quality of life and preserve functionality in CMT patients.

Familial congenital bilateral vocal fold paralysis: a novel gene translocation

OBJECTIVES

True vocal fold (TVF) paralysis is a common cause of neonatal stridor and airway obstruction, though bilateral TVF paralysis is seen less frequently. Rare cases of familial congenital TVF paralysis have been described with implied genetic origin, but few genetic abnormalities have been discovered to date. The purpose of this study is to describe a novel chromosomal translocation responsible for congenital bilateral TVF immobility.

METHODS

The charts of three patients were retrospectively reviewed: a 35 year-old woman and her two children. The mother had bilateral TVF paralysis at birth requiring tracheotomy. Her oldest child had a similar presentation at birth and also required tracheotomy, while the younger child had laryngomalacia without TVF paralysis. Standard karyotype analysis was done using samples from all three patients and the parents of the mother, to assess whether a chromosomal abnormality was responsible.

RESULTS

Karyotype analysis revealed the same balanced translocation between chromosomes 5 and 14, t(5;14) (p15.3, q11.2) in the mother and her two daughters. No other genetic abnormalities were identified. Neither maternal grandparent had the translocation, which appeared to be a spontaneous mutation in the mother with autosomal dominant inheritance and variable penetrance.

CONCLUSIONS

A novel chromosomal translocation was identified that appears to be responsible for familial congenital bilateral TVF paralysis. While there are other reports of genetic abnormalities responsible for this condition, we believe this is the first describing this particular translocation.

Late-onset Charcot-Marie-Tooth disease 4F caused by periaxin gene mutation

We identified the main features of Charcot-Marie-Tooth (CMT) disease, type 4F, caused by a periaxin gene (PRX) mutation in Japanese patients. Periaxin is known as one of the key myelination molecules, forming tight junction between myelin loop and axon. We collected 427 DNA samples from individuals with CMT or CMT-related neuropathy, negative for PMP22 duplication. We investigated PRX mutations using a purpose-built resequencing array screen during the period 2006-2012. We detected two types of PRX mutations in three patients; one patient showed a novel homozygous p.D651N mutation and the other two showed homozygous p.R1070X mutation. All PRX mutations reported so far have been of nonsense or frameshift type. In this study, we found homozygous missense mutation p.D651N. Aspartate 651 is located in a repeat domain; its position might indicate an important function. PRX mutations usually lead to early-onset, autosomal-recessive demyelinating CMT neuropathy 4F (CMT4F) or Dejerine-Sottas disease; their clinical phenotypes are severe. In our three patients, the onset of the disease was at the age of 27 years or later, and their clinical phenotypes were milder compared with those reported in previous studies. We showed a variation of clinical phenotypes for CMT4F caused by a novel, nonsense PRX mutation.