Clinical, Genetic, and Disability Profile of Pediatric Distal Hereditary Motor Neuropathy

Clinical and Genetic Aspects of Childhood-Onset Demyelinating Charcot-Marie-Tooth's Disease in Brazil

Charcot-Marie-Tooth's disease (CMT) represents the most common inherited neuropathy. Most patients are diagnosed during late stages of disease course during adulthood. We performed a review of clinical, neurophysiological, and genetic diagnoses of 32 patients with genetically defined childhood-onset demyelinating CMT under clinical follow-up in a Brazilian Center for Neuromuscular Diseases from January 2015 to December 2019. The current mean age was 33.1 ± 18.3 years (ranging from 7 to 71 years) and mean age at defined genetic diagnosis was 36.1 ± 18.3 years. The mean age at onset was 6.1 ± 4.4 years. The most common initial complaint was bilateral pes cavus. The genetic basis included PMP22 duplication (CMT1A) ( n  = 18), GJB1 (CMTX1) ( n  = 5), MPZ (CMT1B) ( n  = 3), FIG4 (CMT4J) ( n  = 3), SH3TC2 (CMT4C) ( n  = 1), PLEKHG5 (CMTRIC) ( n  = 1), and PRX (CMT4F) ( n  = 1). Almost all patients ( n  = 31) presented with moderate or severe compromise in the CMT neuropathy score 2 with the highest values observed in CMT1B. Medical history disclosed obstructive sleep apnea ( n  = 5), aseptic meningitis ( n  = 1/ MPZ ), akinetic-rigid parkinsonism ( n  = 1/ FIG4 ), and overlapping chronic inflammatory demyelinating polyneuropathy ( n  = 1/ MPZ ). Motor conduction block was detected in three individuals ( PMP22 , FIG4 , MPZ ). Acute denervation occurred in seven patients. Nonuniform demyelinating patterns were seen in four individuals (two CMT1A, one CMT1B, and one CMTX1). Abnormal cerebral white matter findings were detected in CMT1A and CMTX1, while hypertrophic roots were seen in CMT1A, CMT1B, and CMTX1. Our study emphasizes a relative oligogenic basis in childhood-onset demyelinating CMT and atypical findings may be observed especially in MPZ , PMP22 , and GJB1 gene variants.

One-year changes in clinical and balance parameters in individuals of different subtypes of migraine

BACKGROUND

Migraine has been associated with balance dysfunction, more pronounced in patients with aura and chronic migraine. Also, it has been suggested that balance deficits are progressive through the migraineurs lifetime.

OBJECTIVE

To analyze the one-year progression of balance parameters and clinical parameters associated with balance in female patients with and without migraine.

DESIGN

Prospective cohort study.

METHODS

The participants were distributed in four groups: control (CG; n = 27) migraine with aura (MA; n = 25), migraine without aura (MwA; n = 26), and chronic migraine (CM; n = 27). They performed the Sensory Organization Test, Motor Control Test and Adaptation Test protocols of dynamic posturography tests. Questionnaires about fear of falls, dizziness disability, and kinesiophobia were administered. These assessments were performed twice: baseline and after 1-year (follow-up). No intervention was performed for balance improvement, and the participants maintained their usual migraine treatment prescribed.

RESULTS

None of the groups differed in balance tests between baseline and follow-up. We observed a reduction in migraine frequency in MA (-2.2 days, p = 0.01) and CM (-10.8 days, p < 0.001) groups, and in the migraine intensity (-2.3 points, p = 0.001) in CM group. Significant decreases in the scores of fear of falling, dizziness disability, and kinesiophobia were observed in the migraine groups (p < 0.05), but the differences did not exceed the minimal detectable change of the questionaries scores.

CONCLUSION

Women with different migraine subtypes did not present balance changes in a one-year interval. The improvements in migraine's clinical features were not accompanied by improvements in balance parameters.

Genetic spectrum in a cohort of patients with distal hereditary motor neuropathy

Background

Distal hereditary motor neuropathy (dHMN) is a heterogeneous group of diseases characterized by exclusive degeneration of peripheral motor nerves, while only 20.0–47.8% of dHMN patients are genetically identified. Recently, GGC expansion in the 5’UTR of NOTCH2NLC has been associated with dHMN. Accordingly, short tandem repeat (STR) should be further explored in genetically unsolved patients with dHMN.

Methods

A total of 128 patients from 90 unrelated families were clinically diagnosed as dHMN, and underwent a comprehensively genetic screening. Skin biopsies were conducted with routine protocols.

Results

Most patients showed chronic distal weakness of lower limbs (121/128), while 20 patients initially had asymmetrical involvements, 14 had subclinical sensory abnormalities, 11 had pyramidal impairments, five had cerebellar disturbance, and four had hyperCKmia. The rate of genetic detection was achieved in 36.7% (33/90), and the rate increased to 46.7% (42/90) if patients with variants uncertain significance were included. The most common causative genes included chaperone‐related genes (8/33, 24.2%), tRNA synthetase genes (4/33, 12.1%), and cytoskeleton‐related genes (4/33, 12.1%). Additionally, two dominant inherited families were attributed to abnormal expansion of GGC repeats in the 5‘UTR of NOTCH2NLC; and a patient with dHMN and cerebellar symptoms had CAG repeat expansion in the ATXN2 gene. Skin biopsy from patients with GGC expansion in NOTCH2NLC revealed typical intranuclear inclusions on histological and ultrastructural examinations.

Interpretations

This study further extends the genetic heterogeneity of dHMN. Given some dHMN patients may be associated with nucleotides repeat expansion, STR screening is necessary to perform in genetically unsolved patients.

tRNA overexpression rescues peripheral neuropathy caused by mutations in tRNA synthetase

[Figure: see text].

Pediatric inherited peripheral neuropathy: a prospective study at a Spanish referral center

Background

Single‐center clinical series provide important information on genetic distribution that can guide genetic testing. However, there are few such studies on pediatric populations with inherited peripheral neuropathies (IPNs).

Methods

Thorough genetic testing was performed on IPN patients under 20 years of age from a geographically well‐defined Mediterranean area (Valencian Community, Spain), annually assessed with the Charcot–Marie–Tooth disease Pediatric Scale (CMTPedS).

Results

From 86 families with IPNs, 99 patients (59 males) were identified, 85 with sensorimotor neuropathy or CMT (2/3 demyelinating form) and 14 with distal hereditary motor neuropathy (dHMN). Genetic diagnosis was achieved in 79.5% families, with a similar mutation detection rate in the demyelinating (88.7%) and axonal (89.5%) forms, significantly higher than in the dHMN families (27.3%). CMT1A was the most common subtype, followed by those carrying heterozygous mutations in either the GDAP1 or GJB1 genes. Mutations in 15 other genes were identified, including a new pathogenic variant in the ATP1A gene. The CMTPedS detected significant disease progression in all genetic subtypes of CMT, at a rate of 1.84 (±3.7) over 1 year (p < 0.0005, n = 62) and a 2‐year rate of 3.6 (±4.4: p < 0.0005, n = 45). Significant disease worsening was also detected for CMT1A over 1 (1.7 ± 3.6, p < 0.05) and 2 years (4.2 ± 4.3, p < 0.0005).

Conclusions

This study highlights the unique spectrum of IPN gene frequencies among pediatric patients in this specific geographic region, identifying the CMTPedS as a sensitive tool to detect significant disease worsening over 1 year that could help optimize the design of clinical trials.