Kon-Ping Lin

The Mutational Spectrum in a Cohort of Charcot-Marie-Tooth Disease Type 2 among the Han Chinese in Taiwan

Background Charcot-Marie-Tooth disease type 2 (CMT2) is a clinically and genetically heterogeneous group of inherited axonal neuropathies. The aim of this study was to extensively investigate the mutational spectrum of CMT2 in a cohort of patients of Han Chinese. Methodology and Principal Findings Genomic DNA from 36 unrelated Taiwanese CMT2 patients of Han Chinese descent was screened for mutations in the coding regions of the MFN2, RAB7, TRPV4, GARS, NEFL, HSPB1, MPZ, GDAP1, HSPB8, DNM2, AARS and YARS genes. Ten disparate mutations were identified in 14 patients (38.9% of the cohort), including p.N71Y in AARS (2.8%), p.T164A in HSPB1 (2.8%), and p.[H256R]+[R282H] in GDAP1 (2.8%) in one patient each, three NEFL mutations in six patients (16.7%) and four MFN2 mutations in five patients (13.9%). The following six mutations were novel: the individual AARS, HSPB1 and GDAP1 mutations and c.475-1G>T, p.L233V and p.E744M mutations in MFN2. An in vitro splicing assay revealed that the MFN2 c.475-1G>T mutation causes a 4 amino acid deletion (p.T159_Q162del). Despite an extensive survey, the genetic causes of CMT2 remained elusive in the remaining 22 CMT2 patients (61.1%). Conclusions and Significance This study illustrates the spectrum of CMT2 mutations in a Taiwanese CMT2 cohort and expands the number of CMT2-associated mutations. The relevance of the AARS and HSPB1 mutations in the pathogenesis of CMT2 is further highlighted. Moreover, the frequency of the NEFL mutations in this study cohort was unexpectedly high. Genetic testing for NEFL and MFN2 mutations should, therefore, be the first step in the molecular diagnosis of CMT2 in ethnic Chinese.

FUS, TARDBP, and SOD1 mutations in a Taiwanese cohort with familial ALS.

The cause of familial amyotrophic lateral sclerosis (FALS) has been attributed to mutations in several genes. The authors analyzed these genes, including SOD1, FUS, VAPB, ANG, TDP-43, FIG4, and CHMP2B, in a cohort of 15 index patients of Han Chinese descent with adult-onset FALS. Seven different mutations in eight patients, including three in SOD1 (G85R, T137R, and G138E), two in exon 15 of FUS (H517D and R521H), and two in exon 6 of TARDBP (M337V and N378D) were identified. Among them, T137R SOD1, G138E SOD1, H517D FUS, and N378D TARDBP were novel. No mutation was found in VAPB, ANG, FIG4, or CHMP2B genes. Mutations in SOD1, FUS, and TARDBP account for 20%, 13.3%, and 20% of FALS, respectively. This study defined the distribution and frequency of mutations of FALS in a Taiwanese Han Chinese population, which not only broadens the spectrum of the mutations causing FALS, but also further highlights the importance of FUS and TARDBP in the pathogenesis of amyotrophic lateral sclerosis (ALS).

Population-specific spectrum of NOTCH3 mutations, MRI features and founder effect of CADASIL in Chinese

Background and purposeCerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a hereditary disorder caused by NOTCH3 mutations and characterized by recurrent subcortical infarctions, dementia and leukoencephalopathy. So far, most clinical, molecular and neuroimaging information has come from Caucasians. Therefore, we investigated the spectrum of NOTCH3 mutations and MRI features in CADASIL patients of Chinese origin on Taiwan.MethodsMutational analysis of NOTCH3 exons 2 to 23 by direct nucleotide sequencing was performed in patients with clinically suspected CADASIL. MRI findings were retrospectively evaluated and scored using a modified Schelten’s scale.ResultsNine different point mutations of NOTCH3 were identified in 21 unrelated patients. Intriguingly, 47.6 % were in exon 11, and 19 % in each of exon 4 and 18. R544C was very common and present in all patients with a mutation in exon 11. Many patients with NOTCH3 R544C share the same haplotype linked to the mutation using markers D19S929 and D19S411, which flank the NOTCH3. The sensitivity of T2-weighted MRI detecting anterior temporal abnormality was only 42.9 %. Furthermore, the neuroimaging evidence of intracerebral hemorrhage (ICH) was present in 23.8 % of the 21 patients.ConclusionsA population-specific mutational spectrum of CADASIL was found in the Chinese patients on Taiwan. The Chinese patients carrying NOTCH3 R544C may descend from a common ancestor. Anterior temporal hyperintensity on T2-weighted MRI may not be a sensitive marker for CADASIL. ICH is a relatively common manifestation of CADASIL in East Asians, especially in the presence of hypertension.

PRRT2 Mutations in Paroxysmal Kinesigenic Dyskinesia with Infantile Convulsions in a Taiwanese Cohort

Background Mutations in the PRRT2 gene have recently been identified in patients with familial paroxysmal kinesigenic dyskinesia with infantile convulsions (PKD/IC) and patients with sporadic PKD/IC from several ethnic groups. To extend these recent genetic reports, we investigated the frequency and identities of PRRT2 mutations in a cohort of Taiwanese patients with PKD/IC. Methodology and Principal Findings We screened all 3 coding exons of PRRT2 for mutations in 28 Taiwanese patients with PKD/IC. Among them, 13 had familial PKD/IC and 15 were apparently sporadic cases. In total, 7 disparate mutations were identified in 13 patients, including 8 familial cases and 5 apparently sporadic cases. The mutations were not present in 500 healthy controls. Four mutations were novel. One patient had a missense mutation and all other patients carried PRRT2 mutations putatively resulting in a protein truncation. Haplotype analysis revealed that 5 of the 7 patients with the PRRT2 p.R217Pfs*8 mutation shared the same haplotype linked to the mutation. Conclusions and Significance PRRT2 mutations account for 61.5% (8 out of 13) of familial PKD/IC and 33.3% (5 out of 15) of apparently sporadic PKD/IC in the Taiwanese cohort. Most patients with the PRRT2 p.R217Pfs*8 mutation in Taiwan likely descend from a single common ancestor. This study expands the spectrum of PKD/IC-associated PRRT2 mutations, highlights the pathogenic role of PRRT2 mutations in PKD/IC, and suggests genetic heterogeneity within idiopathic PKD.

A hexanucleotide repeat expansion in C9ORF72 causes familial and sporadic ALS in Taiwan

A GGGGCC hexanucleotide repeat expansion in the C9ORF72 gene was recently identified as an important cause of familial amyotrophic lateral sclerosis (ALS) and frontotemporal dementia in Caucasian populations. The role of the C9ORF72 repeat expansion in ALS in Chinese populations has received little attention. We therefore performed mutation analyses in a Taiwanese cohort of 22 unrelated familial ALS (FALS) patients and 102 sporadic ALS patients of Han Chinese descent. The C9ORF72 mutation was found in 4 FALS (18.2%; 4/22) and 2 sporadic ALS patients (2.0%; 2/102). The C9ORF72 repeat numbers in the 300 healthy controls and the 118 ALS patients without the C9ORF72 mutation ranged from 3 to 15. Needle biopsy in the left frontal cortex of 1 patient with FALS-frontotemporal dementia revealed numerous cytoplasmic TAR DNA-binding protein 43 (TDP-43) inclusions and minimal neuritis, consistent with type B frontotemporal lobar degeneration with TDP-43 (FTLD-TDP) pathology. This study clearly demonstrates the existence and importance of the C9ORF72 hexanucleotide repeat expansion in a Taiwanese ALS cohort of Chinese origin, and supports the global presence of the C9ORF72 repeat expansion in ALS.

Comparison of cerebellar ataxias: A three-year prospective longitudinal assessment.

We quantitatively investigated the clinical severity and progression of diseases with ataxia, as measured with the Scale for the Assessment and Rating of Ataxia, and examined the potential application of the Scale for the Assessment and Rating of Ataxia for future therapeutic trials. Severity of ataxia was assessed in 238 patients with spinocerebellar ataxia type 2, spinocerebellar ataxia type 3, spinocerebellar ataxia type 6, spinocerebellar ataxia type 17, multiple system atrophy‐cerebellar variant, or Gerstman‐Sträussler‐Scheinker disease. Among them, 119 (50%) were longitudinally examined three to seven times, in a period of 8 to 38 months, resulting in a total set of 535 assessments. The differences between spinocerebellar ataxia and multiple system atrophy‐cerebellar variant were ascertained cross‐sectionally and longitudinally. Gerstman‐Sträussler‐Scheinker disease had the fastest progression, followed by multiple system atrophy‐cerebellar variant, spinocerebellar ataxia type 17, spinocerebellar ataxia type 3, spinocerebellar ataxia type 2, and spinocerebellar ataxia type 6. Patients with multiple system atrophy‐cerebellar variant had a faster progression in gait, sitting, speech, and total score than patients with spinocerebellar ataxias. For a randomized, case‐control trial, a sample size of 47 for spinocerebellar ataxia and 85 for multiple system atrophy‐cerebellar variant in the treatment or placebo arms would have a sufficient statistical power to demonstrate the efficacy of a new therapy that would retard ataxia progression by 1 point per year as measured by the Scale for the Assessment and Rating of Ataxia. The results will have a significant impact on the planning and implementation of future therapeutic trials of spinocerebellar ataxia and multiple system atrophy‐cerebellar variant.

Lead, Mercury, and Arsenic Poisoning Due to Topical Use of Traditional Chinese Medicines

BACKGROUND Metal poisonings through a mucocutaneous route are reported rarely in the literature. METHODS We report 2 cases of heavy metal intoxication from inappropriate use of Chinese mineral medicines confirmed by toxicologic investigations. RESULTS A 51-year-old man developed perianal gangrene and a high fever after a 2-week anal use of hong-dan herbal mixtures for anal fistula. He presented gastrointestinal and constitutional symptoms, followed by skin rash, anemia, hair loss, peripheral neuropathy, and muscle atrophy. Elevated urine arsenic and mercury confirmed the heavy metal poisonings. The hong-dan mixture contained lead tetraoxide, arsenic, and mercury. He was treated with 2,3-dimercapto-1-propanesulfonic acid, with partial improvement, but peripheral neuropathy persists 4 years later. A 75-year-old man developed anorexia, weight loss, headache, dizziness, nausea, vomiting, constipation, weakness, and anemia after a 3-month use of an herbal patch for chronic leg ulcer. His blood lead concentration was 226 μg/dL, and the lead content of the herbal patch was 517 mg/g. Chelation with ethylene diamine tetraacetic acid and dimercaptosuccinic acid was followed by clinical recovery. CONCLUSION These cases documented serious systemic poisoning after the short-term use of traditional Chinese medicines containing heavy metals in damaged or infected tissue.

Efficacy of Botulinum Toxin Type A in the Relief of Carpal Tunnel Syndrome

AbstractBackground and objectives: Botulinum toxin type A has been shown to relieve primary headaches, myofascial pain and various neuropathic pains. Carpal tunnel syndrome (CTS) is a common disorder resulting from median nerve compression at the wrist. As reports of botulinum toxin A in the treatment of CTS were limited, this study set out to evaluate the safety and tolerability of botulinum toxin A and its effects on the relief of nerve entrapment and pain in patients with CTS. Methods: We conducted an open-label, prospective pilot study using 60 units of botulinum toxin A injected intracarpally in patients with primary CTS. Changes in median nerve conduction velocities, distal latencies, compound muscle action potentials and visual analogue scale (VAS) pain scores were evaluated for 3 months following injection. All adverse experiences, reported spontaneously or observed directly by the investigator, were recorded. Results: Five women aged 52.2 ± 2.5 years with 1–2 years’ history of CTS were enrolled. Botulinum toxin A was well tolerated and safe. No exacerbated hand weakness was observed in any of the patients. At 3 months, pain was lessened in three patients, remained static in one patient, and was aggravated in one patient. The VAS pain score showed a trend to improvement during the 3 months of follow-up, although it did not reach statistical significance (p = 0.2). Conclusion: Our data suggest long-lasting antinociceptive effects of botulinum toxin A rather than electrophysiological restoration in patients with CTS. Intracarpal injection of botulinum toxin A was shown to be well tolerated and safe. A double-blind, placebo-controlled trial of botulinum toxin A in CTS is warranted since the current study may have been confounded by the placebo effect of intracarpal injection.

Migraine is associated with a higher risk of transient global amnesia: a nationwide cohort study.

The association between migraine and transient global amnesia (TGA) is not determined. Only two clinic‐based studies showed that TGA patients had a higher frequency of migraine history. Our population‐based study aimed to investigate whether migraine patients were associated with a higher risk of developing TGA.

A novel TFG mutation causes Charcot-Marie-Tooth disease type 2 and impairs TFG function

Objective: To describe a novel mutation in TRK-fused gene (TFG) as a new cause of dominant axonal Charcot-Marie-Tooth disease (CMT) identified by exome sequencing and further characterized by in vitro functional studies. Methods: Exome sequencing and linkage analysis were utilized to investigate a large Taiwanese family with a dominantly inherited adult-onset motor and sensory axonal neuropathy in which mutations in common CMT2-implicated genes had been previously excluded. Functional effects of the mutant gene products were investigated in vitro. Results: Exome sequencing of 2 affected individuals in this family revealed a novel heterozygous mutation, c.806G>T (p.Gly269Val), in TFG that perfectly cosegregates with the CMT2 phenotype in all 27 family members. This mutation occurs at an evolutionarily conserved residue and is absent in the 1,140 ethnically matched control chromosomes. Genome-wide linkage study also supported its disease-causative role. Cell transfection studies showed that the TFG p.Gly269Val mutation increased the propensity of TFG proteins to form aggregates, resulting in sequestration of both mutant and wild-type TFG proteins and might thus deplete functional TFG molecules. The secreted Gaussia luciferase reporter assay demonstrated that inhibition of endogenous TFG compromised the protein secretion pathways, which could only be rescued by expressing wild-type TFG but not the p.Gly269Val altered proteins. TFG mutation was not found in 55 additional unrelated patients with CMT2, suggesting its rarity. Conclusion: This study identifies a new cause of dominant CMT2 and highlights the importance of TFG in the protein secretory pathways that are essential for proper functioning of the human peripheral nervous system.