Linkage analysis and whole exome sequencing reveals AHNAK2 as a novel genetic cause for autosomal recessive CMT in a Malaysian family.

Charcot-Marie-Tooth (CMT) disease is a form of inherited peripheral neuropathy that affects motor and sensory neurons. To identify the causative gene in a consanguineous family with autosomal recessive CMT (AR-CMT), we employed a combination of linkage analysis and whole exome sequencing. After excluding known AR-CMT genes, genome-wide linkage analysis mapped the disease locus to a 7.48-Mb interval on chromosome 14q32.11-q32.33, flanked by the markers rs2124843 and rs4983409. Whole exome sequencing identified two non-synonymous variants (p.T40P and p.H915Y) in the AHNAK2 gene that segregated with the disease in the family. Pathogenic predictions indicated that p.T40P is the likely causative allele. Analysis of AHNAK2 expression in the AR-CMT patient fibroblasts showed significantly reduced mRNA and protein levels. AHNAK2 binds directly to periaxin which is encoded by the PRX gene, and PRX mutations are associated with another form of AR-CMT (CMT4F). The altered expression of mutant AHNAK2 may disrupt the AHNAK2-PRX interaction in which one of its known functions is to regulate myelination.

X-linked Charcot-Marie-Tooth disease predominates in a cohort of multiethnic Malaysian patients.

INTRODUCTION: Data regarding Charcot-Marie-Tooth disease is lacking in Southeast Asian populations. We investigated the frequency of the common genetic mutations in a multiethnic Malaysian cohort. METHODS: Patients with features of Charcot-Marie-Tooth disease or hereditary liability to pressure palsies were investigated for PMP22 duplication, deletion, and point mutations and GJB1, MPZ, and MFN2 point mutations. RESULTS: Over a period of 3 years, we identified 25 index patients. A genetic diagnosis was reached in 60%. The most common were point mutations in GJB1, accounting for X-linked Charcot-Marie-Tooth disease (24% of the total patient population), followed by PMP22 duplication causing Charcot-Marie-Tooth disease type 1A (20%). We also discovered 2 novel GJB1 mutations, c.521C>T (Proline174Leucine) and c.220G>A (Valine74Methionine). CONCLUSIONS: X-linked Charcot-Marie-Tooth disease was found to predominate in our patient cohort. We also found a better phenotype/genotype correlation when applying a more recently recommended genetic approach to Charcot-Marie-Tooth disease.

Clinical Characteristics, Pain, and Quality of Life Experiences of Trigeminal Neuralgia in a Multi-Ethnic Asian Cohort.

AIMS: To describe the clinical characteristics of trigeminal neuralgia (TN) in a multi-ethnic Malaysian population and to relate them to standardized measures of pain severity, anxiety, depression, and quality of life (QoL). METHODS: Patients fulfilling the International Headache Society (IHS) criteria for TN were prospectively interviewed for their demographic and clinical data. Pain intensity was rated with a visual analog scale (VAS), anxiety and depression were determined by the Hospital Anxiety and Depression Scale (HADS), and QoL was assessed by the Short-Form 36 (SF-36) questionnaire. Chi-square, Mann-Whitney U, and Spearman correlation tests were used to test for differences considering a significance level of P < .05. RESULTS: Of the 75 included patients, 52 (69.3%) were women with a mean ± standard deviation (SD) onset age of 52.0 ± 12.7 years, and 57.3% were Chinese, 24.0% Malay, and 18.7% Indian. Pain was more common on the right side (69.3%) and in the maxillary and mandibular divisions. VAS scores for pain at its worst were higher in anxious/borderline anxious patients compared to non-anxious patients (89.5 ± 15.9 vs 80.9 ± 17.2, respectively; P < .05), and VAS scores for pain at its least were higher in depressed/borderline depressed subjects compared to non-depressed subjects (38.4 ± 25.8 vs 23.0 ± 19.2, respectively; P < .05). Chinese patients had lower VAS scores for pain at its least compared to Indian patients (19.7 ± 16.1 vs 39.9 ± 24.7; P < .01). TN patients scored lower in all eight domains of the SF-36 compared to the general population. Indian patients had lower scores in role limitations due to physical health (8.9 ± 23.2 vs 49.4 ± 43.8; P < .01) and social function (56.3 ± 13.6 vs 76.5 ± 23.6; P < .01) than Chinese patients, and Malay patients had lower mental health scores compared to Chinese patients (59.1 ± 19.5 vs 73.0 ± 21.0; P < .01). CONCLUSION: Clinical characteristics of TN patients were similar to those of other populations. There were differences in pain ratings and QoL between TN patients of different ethnicities, as well as between those with anxiety and depression.

A Double-Blind Randomized Controlled Trial Investigating the Most Efficacious Dose of Botulinum Toxin-A for Sialorrhea Treatment in Asian Adults with Neurological Diseases.

This study aims to determine the most efficacious dose of Botulinum neurotoxin type A (BoNT-A) in reducing sialorrhea in Asian adults with neurological diseases. A prospective, double-blind randomized controlled trial was conducted over 24 weeks. Thirty patients with significant sialorrhea were randomly assigned to receive a BoNT-A (Dysport(®)) injection into the submandibular and the parotid glands bilaterally via an ultrasound guidance. The total dose given per patient was either BoNT-A injection of (i) 50 U; (ii) 100 U; or (iii) 200 U. The primary outcome was the amount of saliva reduction, measured by the differential weight (wet versus dry) of intraoral dental gauze at baseline and at 2, 6, 12, and 24 weeks after injection. The secondary outcome was the subjective report of drooling using the Drooling Frequency and Severity Scale (DFS). Saliva reduction was observed in response to all BoNT-A doses in 17 patients who completed the assessments. Although no statistically significant difference among the doses was found, the measured reduction was greater in groups that received higher doses (100 U and 200 U). The group receiving 200 U of Dysport(®) showed the greatest reduction of saliva until 24 weeks and reported the most significant improvement in the DFS score.