1
|
Diagnostic value of nerve conduction study in NOTCH2NLC-related neuronal intranuclear inclusion disease. J Peripher Nerv Syst 2023; 28:629-641. [PMID: 37749855 DOI: 10.1111/jns.12599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 09/18/2023] [Accepted: 09/22/2023] [Indexed: 09/27/2023]
Abstract
BACKGROUND AND AIMS Neuronal intranuclear inclusion disease (NIID) is a rare progressive neurodegenerative disorder mainly caused by abnormally expanded GGC repeats within the NOTCH2NLC gene. Most patients with NIID show polyneuropathy. Here, we aim to investigate diagnostic electrophysiological markers of NIID. METHODS In this retrospective dual-center study, we reviewed 96 patients with NOTCH2NLC-related NIID, 94 patients with genetically confirmed Charcot-Marie-Tooth (CMT) disease, and 62 control participants without history of peripheral neuropathy, who underwent nerve conduction studies between 2018 and 2022. RESULTS Peripheral nerve symptoms were presented by 53.1% of patients with NIID, whereas 97.9% of them showed peripheral neuropathy according to electrophysiological examinations. Patients with NIID were characterized by slight demyelinating sensorimotor polyneuropathy; some patients also showed mild axonal lesions. Motor nerve conduction velocity (MCV) of the median nerve usually exceeded 35 m/s, and were found to be negatively correlated with the GGC repeat sizes. Regarding the electrophysiological differences between muscle weakness type (n = 27) and non-muscle weakness type (n = 69) of NIID, nerve conduction abnormalities were more severe in the muscle weakness type involving both demyelination and axonal impairment. Notably, specific DWI subcortical lace sign was presented in only 33.3% of muscle weakness type, thus it was difficult to differentiate them from CMT. Combining age of onset, distal motor latency, and compound muscle action potential of the median nerve showed the optimal diagnostic performance to distinguish NIID from major CMT (AUC = 0.989, sensitivity = 92.6%, specificity = 97.4%). INTERPRETATION Peripheral polyneuropathy is common in NIID. Our study suggest that nerve conduction study is useful to discriminate NIID.
Collapse
|
2
|
A novel splicing mutation in 5'UTR of GJB1 causes X-linked Charcot-Marie-tooth disease. Mol Genet Genomic Med 2023; 11:e2108. [PMID: 36394156 PMCID: PMC10009907 DOI: 10.1002/mgg3.2108] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 11/08/2022] [Accepted: 11/09/2022] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Charcot-Marie-Tooth (CMT) disease is the most frequent hereditary motor sensory neurological disease. GJB1 gene is the second most frequent cause of CMT, accounting for approximately 10% of CMT cases worldwide. We identified a large Han family with X-linked CMT disease. METHODS In this study, the probands and his mother underwent electrophysiological examinations and other family members were assessed retrospectively. Whole-exome sequencing, Sanger sequencing, and SNP array linkage analysis were performed to find and confirm the variant. The functional effect of the identified variant was further investigated in HEK293 cells and MCF-7 cells by minigene splicing assay. RESULTS The affected individuals had some clinical symptoms including symmetric atrophy and progressive weakness of the distal muscles in their twenties. Electrophysiological examinations result in peripheral nerve injury of the upper and lower limbs. Whole-exome sequencing identified a novel hemizygous deletion mutation (NM_000166: c.-16-8_-14del) in the GJB1 gene. SNP array linkage analysis and co-segregation analysis confirmed this mutation. Minigene splicing assay verified that this mutation leads to the activation of cryptic splicing sites in exon 2 which results in the deletion of exon 2. CONCLUSION Our study provides theoretical guidance for prenatal diagnosis and subsequent fertility of this family. This result expands the spectrum of mutations in GJB1 known to be associated with CMTX and contributes to the diagnosis of CMT and clinical genetic counseling.
Collapse
|
3
|
HINT1 neuropathy: Expanding the genotype and phenotype spectrum. Clin Genet 2022; 102:379-390. [PMID: 35882622 DOI: 10.1111/cge.14198] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 07/20/2022] [Accepted: 07/21/2022] [Indexed: 01/07/2023]
Abstract
Inherited peripheral neuropathy (IPN) is a heterogeneous group of disorders due to pathogenic variation in more than 100 genes. In 2012, the first cases of IPN associated with HINT1 pathogenic variations were described in 33 families sharing the same phenotype characterized by an axonal neuropathy with neuromyotonia and autosomal recessive inheritance (NMAN: OMIM #137200). Histidine Triad Nucleotide Binding Protein 1 regulates transcription, cell-cycle control, and is possibly involved in neuropsychiatric pathophysiology. Herein, we report seven French patients with NMAN identified by Next Generation Sequencing. We conducted a literature review and compared phenotypic and genotypic features with our cohort. We identified a new HINT1 pathogenic variation involved in NMAN: c.310G>C p.(Gly104Arg). This cohort is comparable with literature data regarding age of onset (7,4yo), neuronal involvement (sensorimotor 3/7 and motor pure 4/7), and skeletal abnormalities (scoliosis 3/7, feet anomalies 6/7). We expand the phenotypic spectrum of HINT1-related neuropathy by describing neurodevelopmental or psychiatric features in six out of seven individuals such as generalized anxiety disorder (GAD), obsessive-compulsive disorder (OCD), mood disorder and attention deficit hyperactivity disorder (ADHD). However, only 3/128 previously described patients had neuropsychiatric symptomatology or neurodevelopmental disorder. These features could be part of HINT1-related disease, and we should further study the clinical phenotype of the patients.
Collapse
|
4
|
Validation of the Italian version of the Pediatric CMT Quality of Life Outcome Measure. J Peripher Nerv Syst 2022; 27:127-130. [PMID: 35416371 PMCID: PMC9324941 DOI: 10.1111/jns.12494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 04/10/2022] [Indexed: 11/29/2022]
Abstract
BACKGROUND AND AIMS The pediatric Charcot-Marie-Tooth (CMT) specific Quality of Life (QOL) outcome measure (pCMT-QOL) is a recently developed and validated patient reported measure of health QOL for children with CMT. The aim of this study was to provide and validate an Italian version of the pCMT-QOL. METHODS The original English version was translated and adapted into Italian using standard procedures. pCMT-QOL was administered to patients genetically diagnosed with CMT, aged 8 to 18 years. A retest was given 2 weeks later to assess reliability in all patients. RESULTS A total of 22 patients (median age 14 years, DS 2.5; M:F 1:1) affected with CMT (19 CMT1A, 2 CMT2A, 1 CMT2K) were assessed as part of their clinical visit. The Italian-pCMT-QOL demonstrate a high test-retest reliability. None of the patients experienced difficulty in completing the questionnaire, no further corrections were needed after administration in patients. INTERPRETATION The Italian-pCMT-QOL is a reliable, culturally adapted, and comparable version of the original English pCMT-QOL.
Collapse
|
5
|
MPZ gene variant site in Chinese patients with Charcot-Marie-Tooth disease. Mol Genet Genomic Med 2022; 10:e1890. [PMID: 35174662 PMCID: PMC9000946 DOI: 10.1002/mgg3.1890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 01/13/2022] [Accepted: 01/18/2022] [Indexed: 11/15/2022] Open
Abstract
Background Charcot–Marie–Tooth disease (CMT) is a hereditary monogenic peripheral nerve disease. Variants in the gene encoding myelin protein zero (MPZ) lead to CMT, and different variants have different clinical phenotypes. A variant site, namely, c.389A > G (p.Lys130Arg), in the MPZ gene has been found in Chinese people. The pathogenicity of this variant has been clarified through pedigrees, and peripheral blood‐related functional studies have been conducted. Method Whole‐exome sequencing and Sanger sequencing were used to detect the c.389A > G (p.Lys130Arg) variant in the MPZ gene in family members of the proband. Physical examination was performed in the case group to assess the clinical characteristics of MPZ site variants. The expression of MPZ and phosphorylated MPZ in the blood of 12 cases and 12 randomly selected controls was compared by RT–qPCR, Western blotting, and ELISA. Results The proband and 12 of her family members presented the AG genotype with different clinical manifestations. The expression of MPZ mRNA in the case group was increased compared with that in the control group, and the levels of MPZ and phosphorylated MPZ in peripheral blood were higher than those in normal controls. Conclusion The heterozygous genotype of the c.389A > G (p.Lys130Arg) variant in the MPZ gene mediated the increase in MPZ and phosphorylated MPZ levels in peripheral blood and was found to be involved with CMT.
Collapse
|
6
|
SPG9A with the new occurrence of an ALDH18A1 mutation in a CMT1A family with PMP22 duplication: case report. BMC Neurol 2021; 21:64. [PMID: 33573605 PMCID: PMC7876803 DOI: 10.1186/s12883-021-02087-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Accepted: 02/02/2021] [Indexed: 12/03/2022] Open
Abstract
Background ALDH18A1 mutations lead to delta-1-pyrroline-5-carboxylate-synthetase (P5CS) deficiency, which is a urea cycle-related disorder including SPG9A, SPG9B, autosomal dominant cutis laxa-3 (ADCL3), and autosomal recessive cutis laxa type 3A (ARCL3A). These diseases exhibit a broad clinical spectrum, which makes the diagnosis of P5CS deficiency difficult. We report here a rare Japanese family including both patients with an ALDH18A1 mutation (SPG9A) and ones with CMT1A. Case presentation A Japanese family included five patients with the CMT phenotype and five with the HSP phenotype in four generations. The patients with the HSP phenotype showed a pure or complicated form, and intrafamilial clinical variability was noted. Genetically, FISH analysis revealed that two CMT patients had a PMP22 duplication (CMT1A). Exome analysis and Sanger sequencing revealed five HSP patients had an ALDH18A1 heterozygous mutation of c.755G > A, which led to SPG9A. Haplotype analysis revealed that the ALDH18A1 mutation must have newly occurred. To date, although de novo mutations of ALDH18A1 have been described in ADCL3A, they were not mentioned in SPG9A in earlier reports. Thus, this is the first SPG9A family with a de novo mutation or the new occurrence of gonadal mosaicism of ALDH18A1. Analysis of serum amino acid levels revealed that two SPG9A patients and two unaffected family members had low citrulline levels and one had a low level of ornithine. Conclusions Since the newly occurring ALDH18A1 mutation, c.755G > A, is the same as that in two ADHSP families and one sporadic patient with SPG9A reported previously, this genomic site might easily undergo mutation. The patients with the c.755G > A mutation in our family showed clinical variability of symptoms like in the earlier reported two families and one sporadic patient with this mutation. Further studies are required to clarify the relationship between the amino acid levels and clinical manifestations, which will reveal how P5CS deficiency influences disease phenotypes including ARCL3A, ADCL3, SPG9B, and SPG9A.
Collapse
|
7
|
Ataxia pancytopenia syndrome due to SAMD9L mutation presenting as demyelinating neuropathy. J Peripher Nerv Syst 2020; 25:433-437. [PMID: 32808377 DOI: 10.1111/jns.12409] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 08/09/2020] [Accepted: 08/10/2020] [Indexed: 12/01/2022]
Abstract
Ataxia pancytopenia (ATXPC) syndrome due to gain-of-function pathogenic variants in the SAMD9L gene has been described in 38 patients to date. It is characterized by variable neurological and hematological phenotypes including ataxia, pyramidal signs, cytopenias, and hematological malignancies. Peripheral neuropathy with slowing of conduction velocities has been reported in only two affected individuals. We describe a female with childhood onset neuropathy diagnosed as Charcot-Marie-Tooth disease type 1 with onset of cerebellar ataxia in her 50s. Cerebellar, pyramidal, and neuropathic features were found on examination. Additionally, she also had conjunctival telangiectasia. Nerve conduction studies confirmed a demyelinating neuropathy. MRI brain showed cerebellar atrophy with diffuse white matter hyperintensities. OCT demonstrated global thinning of the retinal nerve fiber layer (RNFL). Full blood count has always been normal. A previously described pathogenic variant in SAMD9L [c.2956C>T p.(Arg986Cys)] was identified on whole exome sequencing. This case extends the previously described phenotype to include conjunctival telangiectasia and RNFL thinning and suggests that ATXPC syndrome should be considered in the differential for inherited demyelinating neuropathies.
Collapse
|
8
|
Validation of the Italian version of the Charcot-Marie-Tooth disease Pediatric Scale. J Peripher Nerv Syst 2020; 25:138-142. [PMID: 32394473 DOI: 10.1111/jns.12383] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 05/06/2020] [Indexed: 11/30/2022]
Abstract
The Charcot-Marie-Tooth disease Pediatric Scale (CMTPedS) is a Rasch-built clinical outcome measure of disease severity. It is valid, reliable, and responsive to change for children and adolescents aged 3 to 20 years. The aim of this study was to translate and validate an Italian version of the CMTPedS using a validated framework of transcultural adaptation. The CMTPedS (Italian) was translated and culturally adapted from source into Italian by two experts in CMT with good English language proficiency. The two translations were reviewed by a panel of experts in CMT. The agreed provisional version was back translated into English by a professional translator. The definitive Italian version was developed during a consensus teleconference by the same panel. CMT patients were assessed with the final version of the outcome measure and a subset had a second assessment after 2 weeks to evaluate test-retest reliability. Seventeen patients with CMT aged 5 to 20 years (eight female) were evaluated with the CMTPedS (Italian), and test-retest was performed in three patients. The CMTPedS (Italian) showed a high test-retest reliability. No patient had difficulty in completing the scale. The instructions for the different items were clearly understood by clinicians and therefore the administration of the outcome measure was straight forward and easily understood by the children assessed. The CMTPedS (Italian) will be used for clinical follow-up and in clinical research studies in the Italian population. The data is fully comparable to that obtained from the English language version.
Collapse
|
9
|
A recessive Trim2 mutation causes an axonal neuropathy in mice. Neurobiol Dis 2020; 140:104845. [PMID: 32205255 DOI: 10.1016/j.nbd.2020.104845] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Revised: 02/21/2020] [Accepted: 03/18/2020] [Indexed: 01/02/2023] Open
Abstract
We analyzed Trim2A/A mice, generated by CRISPR-Cas9, which have a recessive, null mutation of Trim2. Trim2A/A mice develop ataxia that is associated with a severe loss of cerebellar Purkinje cells and a peripheral neuropathy. Myelinated axons in the CNS, including those in the deep cerebellar nuclei, have focal enlargements that contain mitochondria and neurofilaments. In the PNS, there is a loss of myelinated axons, particularly in the most distal nerves. The pathologically affected neuronal populations - primary sensory and motor neurons as well as cerebellar Purkinje cells - express TRIM2, suggesting that loss of TRIM2 in these neurons results in cell autonomous effects on their axons. In contrast, these pathological findings were not found in a second strain of Trim2 mutant mice (Trim2C/C), which has a partial deletion in the RING domain that is needed for ubiquitin ligase activity. Both the Trim2Aand the Trim2C alleles encode mutant TRIM2 proteins with reduced ubiquitination activity. In sum, Trim2A/A mice are a genetically authentic animal model of a recessive axonal neuropathy of humans, apparently for a function that does not depend on the ubiquitin ligase activity.
Collapse
|
10
|
Walking and weakness in children: a narrative review of gait and functional ambulation in paediatric neuromuscular disease. J Foot Ankle Res 2020; 13:10. [PMID: 32122377 PMCID: PMC7052968 DOI: 10.1186/s13047-020-0378-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Accepted: 02/18/2020] [Indexed: 12/18/2022] Open
Abstract
Background Weakness is the primary impairment in paediatric neuromuscular diseases, impacting gait and gait-related functional activities in ambulant children affected by these rare and often degenerative diseases. Gait speed is an indicator of health and disability, yet gait is a complex, multi-faceted activity. Using the International Classification of Function, Health and Disability (ICF) model, assessment of gait and functional ambulation should consider the impairments, activity limitations and participation restrictions due to disease, and factors related to the environment and the individual person. Methods This narrative review involved a literature search of databases including Medline, Embase and Pubmed from 1946 to October 2019. Inclusion criteria included assessments of gait, endurance and ambulatory function in paediatric (0–18 years) neuromuscular diseases. Results Fifty-two papers were identified reporting assessments of gait speed, timed function, endurance and ambulatory capacity, gait-related balance and qualitative descriptive assessments of gait function and effect of disease on gait and gait-related activities. Gait speed is an indicator of disability and children with neuromuscular disease walk slower than typically developing peers. Increasing disease severity and age were associated with slower walking in children with Duchenne muscular dystrophy and Charcot-Marie-Tooth disease. The six-minute walk test is used widely as a test of endurance and ambulatory capacity; six-minute walk distance was substantially reduced across all paediatric neuromuscular diseases. Endurance and ambulatory capacity was more limited in children with spinal muscular atrophy type 3, congenital muscular dystrophy and older boys with Duchenne muscular dystrophy. Only a few papers considered normalisation of gait parameters accounting for the effect on gait of height in heterogeneous groups of children and linear growth in longitudinal studies. Balance related to gait was considered in five papers, mainly in children with Charcot-Marie-Tooth disease. There was limited investigation of factors including distance requirements and terrain in children’s typical environments and personal factors related to self-perception of disease effect on gait and gait-related function. Conclusion Assessments of gait and functional ambulation are important considerations in documenting disease progression and treatment efficacy in the clinical setting; and in clinical trials of disease-modifying agents and physiotherapeutic interventions in paediatric neuromuscular diseases. There is a need for expert consensus on core gait and functional ambulation assessments for use in clinical and research settings.
Collapse
|
11
|
Neurological safety of oxaliplatin in patients with uncommon variants in Charcot-Marie-tooth disease genes. J Neurol Sci 2020; 411:116687. [PMID: 32018185 DOI: 10.1016/j.jns.2020.116687] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 01/11/2020] [Accepted: 01/13/2020] [Indexed: 10/25/2022]
Abstract
Oxaliplatin therapy can be complicated by chemotherapy-induced peripheral neuropathy (CIPN). Other neurotoxic chemotherapies have been linked to single nucleotide variants (SNV) in Charcot-Marie-Tooth disease (CMT) genes. Whether oxaliplatin carries increased risks of CIPN due to SNV in CMT-associated genes is unknown. 353 patients receiving oxaliplatin in NCCTG N08CB were serially evaluated for CIPN using a validated patient-reported outcome (PRO) instrument, the CIPN20 questionnaire (sensory scale). 49 canonical CMT-associated genes were analyzed for rare and common SNV by nextgen sequencing. The 157 patients with the highest and lowest susceptibility to CIPN (cases and controls) harbored 270 non-synonymous SNV in CMT-associated genes (coding regions). 143 of these were rare, occurring only once ("singletons"). CIPN cases had 0.84 singletons per patient compared with 0.98 in controls. An imbalance in favor of cases was noted only in few genes including PRX, which was previously highlighted as a candidate CIPN gene in patients receiving paclitaxel. However, the imbalance was only modest (5 singleton SNV in cases and 2 in controls). Therefore, while singleton SNV were common, they did overall not portend an increased risk of CIPN. Furthermore, testing CMT-associated genes using recurrent non-synonymous SNV did not reveal any significant association with CIPN. Genetic analysis of patients from N08CB provides clinical guidance that oxaliplatin chemotherapy decisions should not be altered by the majority of SNV that may be encountered in CMT-associated genes when common genetic tests are performed, such as exome or genome sequencing. Oxaliplatin's CIPN risk appears unrelated to CMT-associated genes.
Collapse
|
12
|
Investigation of Mutations in Exon 14 of SH3TC2 Gene and Exon 7 of NDRG1 Gene in Iranian Charcot-Marie-Tooth Disease Type 4 (CMT4D) Patients. IRANIAN JOURNAL OF CHILD NEUROLOGY 2020; 14:93-100. [PMID: 32256628 PMCID: PMC7085125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/26/2017] [Revised: 03/07/2018] [Accepted: 02/16/2019] [Indexed: 10/29/2022]
Abstract
OBJECTIVES Charcot-Marie-tooth disease type 4 (CMT4D) is an autosomal recessive form of Charcot-Marie-tooth disease with an earlier age of onset and greater severity, compared to other types of this disease. CMT4C and CMT4D are the most prevalent subtypes in Mediterranean countries due to the higher rate of consanguineous marriage. In this study, we aimed to identify p.R148X mutation in NDRG1 gene and p.R1109X mutation in SH3TC2 gene (responsible for CMT4D and CMT4C, respectively) and to investigate other possible nucleotide changes in exon 14 of SH3TC2 gene and exon 7 of NDRG1 gene in an Iranian population. MATERIALS & METHODS A total of 24 CMT4D patients, who were referred to Iran Special Medical Center, were clinically and electrophysiologically evaluated in this study. DNA was extracted from the patients' blood samples. Next, polymerase chain reaction (PCR) assay was carried out, and the products were sequenced and analyzed in FinchTV software. RESULTS None of the target mutations were found in this study. Sequencing of SH3TC2 gene showed SNP rs1025476 (g.57975C>T) in 21 (87.5%) patients, including 7 homozygous and 14 heterozygous individuals. CONCLUSION Despite the high rate of mutations in some populations, it seems that they are very rare in Iranian CMT4D patients. Regarding the association of SNP rs1025476 with CMT4D, further assessments are needed to reach a better understanding of genetic markers and their genetic features and to propose better diagnostic and treatment plans for the Iranian population.
Collapse
|
13
|
Neuroinflammation in the pathogenesis of axonal Charcot-Marie-Tooth disease caused by lack of GDAP1. Exp Neurol 2019; 320:113004. [PMID: 31271761 DOI: 10.1016/j.expneurol.2019.113004] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Revised: 06/17/2019] [Accepted: 06/28/2019] [Indexed: 01/17/2023]
Abstract
Mutations in the GDAP1 mitochondrial outer membrane gene cause Charcot-Marie-Tooth (CMT) neuropathy. Reduction or absence of GDAP1 has been associated with abnormal changes in the mitochondrial morphology and dynamics, oxidative stress and changes in calcium homeostasis. Neuroinflammation has been described in rodent models of genetic demyelinating CMT neuropathies but not in CMT primarily associated with axonopathy. Inflammatory processes have also been related to mitochondrial changes and oxidative stress in central neurodegenerative disorders. Here we investigated the presence of neuroinflammation in the axonal neuropathy of the Gdap1-/- mice. We showed by transcriptome profile of spinal cord and the in vivo detection of activated phagocytes that the absence of GDAP1 is associated with upregulation of inflammatory pathways. We observed reactive gliosis in spinal cord with increase of the astroglia markers GFAP and S100B, and the microglia marker IBA1. Additionally, we found significant increase of inflammatory mediators such as TNF-α and pERK, and C1qa and C1qb proteins of the complement system. Importantly, we observed an increased expression of CD206 and CD86 as M2 and M1 microglia and macrophage response markers, respectively, in Gdap1-/- mice. These inflammatory changes were also associated with abnormal molecular changes in synapses. In summary, we demonstrate that inflammation in spinal cord and sciatic nerve, but not in brain and cerebellum, is part of the pathophysiology of axonal GDAP1-related CMT.
Collapse
|
14
|
A novel family with axonal Charcot-Marie-Tooth disease caused by a mutation in the EGR2 gene. J Peripher Nerv Syst 2019; 24:219-223. [PMID: 30843326 DOI: 10.1111/jns.12314] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 02/17/2019] [Accepted: 03/04/2019] [Indexed: 11/30/2022]
Abstract
EGR2 (Early Growth Response 2) is one of the most important transcription factors involved in myelination in the peripheral nervous system. EGR2 mutations typically cause different forms of demyelinating neuropathy, that is, Charcot-Marie-Tooth type 1D (CMT1D), Dejerine-Sottas Syndrome (DSS), and Congenital Hypomyelinating Neuropathy (CHN). However, the EGR2 gene has been recently associated with an axonal phenotype (CMT2) in a large CMT family. Here, we report another CMT family exhibiting an axonal phenotype associated with a missense change (c.1235A>G, p.E412G) in the EGR2 gene. Neurological evaluation of five affected members of the family showed a classical CMT phenotype including distal muscle atrophy and weakness, absence of deep tendon reflexes, pes cavus, and scoliosis. Electrophysiological examination was consistent with a motor-sensory axonal neuropathy. Sural nerve biopsy performed in one patient showed a loss of myelinated and unmyelinated nerve fibers without de-remyelinating signs and onion bulbs. This study confirms the phenotypical heterogeneity of EGR2-related neuropathy, indicating a role for EGR2 in primary axonal degeneration.
Collapse
|
15
|
A cryptic splicing mutation in the INF2 gene causing Charcot-Marie-Tooth disease with minimal glomerular dysfunction. J Peripher Nerv Syst 2019; 24:120-124. [PMID: 30680856 DOI: 10.1111/jns.12308] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Revised: 01/21/2019] [Accepted: 01/22/2019] [Indexed: 12/14/2022]
Abstract
Heterozygous mutations in the inverted formin-2 (INF2) gene provoke focal segmental glomerulosclerosis (FSGS) and intermediate Charcot-Marie-Tooth (CMT) disease with FSGS. Here, we report four patients from a three-generation family with a new cryptic splicing INF2 mutation causing autosomal dominant intermediate CMT with minimal glomerular dysfunction. Three males and one female with a mean age of 51 years (26-87) presented with a slowly progressive sensorimotor polyneuropathy, pes cavus, and kyphoscoliosis. Mean age at CMT disease onset was 11.5 years (3-17), and electrophysiological studies showed demyelinating and axonal features consistent with intermediate CMT. Plasma albumin and creatinine were normal in all four cases, and urine protein was normal in one case and mildly raised in three patients (mean: 0.32 g/L [0.18-0.44], N < 0.14). Genetic analysis found a c.271C > G (p. Arg91Gly) variation in INF2 exon 2, and in vitro splicing assays showed the deletion of the last 120 nucleotides of INF2 exon 2 leading to a 40 amino acids in-frame deletion (p. Arg91_p. Gln130del). This report expands the genetic spectrum of INF2-associated disorders and demonstrates that INF2 mutations may provoke isolated CMT with no clinically relevant kidney involvement. Consequently, INF2 mutation analysis should not be restricted to individuals with coincident neuropathy and renal disease.
Collapse
|
16
|
Mosaicism for a pathogenic MFN2 mutation causes minimal clinical features of CMT2A in the parent of a severely affected child. Neurogenetics 2017; 18:49-55. [PMID: 28063088 PMCID: PMC5243894 DOI: 10.1007/s10048-016-0504-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 12/07/2016] [Indexed: 10/26/2022]
Abstract
Charcot-Marie-Tooth disease (CMT) refers to a genetically heterogeneous group of disorders which cause a peripheral motor and sensory neuropathy. The overall prevalence is 1 in 2500 individuals. Mutations in the MFN2 gene are the commonest cause for the axonal (CMT2) type. We describe a Caucasian 5-year old girl affected by CMT2A since the age of 2 years. She presented with unsteady gait, in-turning of the feet and progressive foot deformities. Nerve conduction studies suggested an axonal neuropathy and molecular testing identified a previously reported pathogenic variant c.1090C > T, p.(Arg364Trp) in the MFN2 gene. This variant was also detected in a mosaic state in blood and saliva by Sanger sequencing in her subjectively healthy father. Next generation sequencing showed that the level of mosaicism was 21% in blood and 24% in saliva. A high recurrence risk was given because the father had proven somatic mosaicism and an affected child implying gonadal mosaicism. The parents were referred for pre-implantation genetic diagnosis. To the best of our knowledge, this is the first reported case of somatic mosaicism for MFN2. This study has important implications for genetic counselling in families with CMT2A.
Collapse
|
17
|
Proteolipid protein modulates preservation of peripheral axons and premature death when myelin protein zero is lacking. Glia 2015; 64:155-74. [PMID: 26393339 DOI: 10.1002/glia.22922] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 09/04/2015] [Indexed: 12/23/2022]
Abstract
Protein zero (P0) is the major structural component of peripheral myelin. Lack of this adhesion protein from Schwann cells causes a severe dysmyelinating neuropathy with secondary axonal degeneration in humans with the neuropathy Dejerine-Sottas syndrome (DSS) and in the corresponding mouse model (P0(null)-mice). In the mammalian CNS, the tetraspan-membrane protein PLP is the major structural myelin constituent and required for the long-term preservation of myelinated axons, which fails in hereditary spastic paraplegia (SPG type-2) and the relevant mouse model (Plp(null)-mice). The Plp-gene is also expressed in Schwann cells but PLP is of very low abundance in normal peripheral myelin; its function has thus remained enigmatic. Here we show that the abundance of PLP but not of other tetraspan myelin proteins is strongly increased in compact peripheral myelin of P0(null)-mice. To determine the functional relevance of PLP expression in the absence of P0, we generated P0(null)*Plp(null)-double-mutant mice. Compared with either single-mutant, P0(null)*Plp(null)-mice display impaired nerve conduction, reduced motor functions, and premature death. At the morphological level, axonal segments were frequently non-myelinated but in a one-to-one relationship with a hypertrophic Schwann cell. Importantly, axonal numbers were reduced in the vital phrenic nerve of P0(null)*Plp(null)-mice. In the absence of P0, thus, PLP also contributes to myelination by Schwann cells and to the preservation of peripheral axons. These data provide a link between the Schwann cell-dependent support of peripheral axons and the oligodendrocyte-dependent support of central axons.
Collapse
|