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OBJECTIVE: Charcot-Marie-Tooth disease covers a group of inherited peripheral neuropathies. The aim of this study was to investigate the effect of targeted next-generation sequencing panels on the molecular diagnosis of Charcot-Marie-Tooth disease and its subtypes in routine clinical practice, and also to show the limitations and importance of next-generation sequencing in the diagnosis of Charcot-Marie-Tooth diseases. METHODS: This is a retrospective study. Three different molecular methods (multiplex ligation probe amplification, next-generation sequencing, and whole-exome sequencing) were used to detect the mutations related to Charcot-Marie-Tooth disease. RESULTS: In total, 64 patients (33 males and 31 females) with suspected Charcot-Marie-Tooth disease were analyzed for molecular etiology. In all, 25 (39%) patients were diagnosed by multiplex ligation probe amplification. With an extra 11 patients with normal PMP22 multiplex ligation probe amplification results that were consulted to our laboratory for further genetic analysis, a total of 50 patients underwent next-generation sequencing for targeted gene panels associated with Charcot-Marie-Tooth disease. Notably, 18 (36%) patients had pathogenic/likely pathogenic variants. Whole-exome sequencing was performed on five patients with normal next-generation sequencing results; the diagnostic yield by whole-exome sequencing was 80% and it was higher in the childhood group. CONCLUSION: The molecular etiology in Charcot-Marie-Tooth disease patients can be determined according to pre-test evaluation, deciding the inheritance type with pedigree analysis, the clinical phenotype, and an algorithm for the genetic analysis. The presence of patients without a molecular diagnosis in all the literature suggests that there are new genes or mechanisms waiting to be discovered in the etiology of Charcot-Marie-Tooth disease.

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Background: Charcot-Marie-Tooth disease type 2Q (CMT2Q) is a rare disorder (< 1/1,000,000 individuals worldwide) linked to chromosome 10p14 in the DHTKD1 gene. This phenotype is characterized by an adolescent or adulthood-onset, slowly progressive distal muscle weakness and symmetrical atrophy associated with reduced or absent deep tendon reflexes. Currently, only two familiar cases from China have been reported: one familiar case of eight individuals affected by isolated DHTKD1 gene mutation and one familiar case of two individuals affected by DHTKD1 gene mutation and GJB1 gene mutation. Case report: We present the case of a 10-year-old male patient with obesity, frequent falls, swollen legs and thighs, and pain in the lower and upper limbs. We performed the clinical evaluation and a clinical targeted exome test, which reported mutations on DHTKD1 y NTRK2 genes. Conclusions: Due to scientific and technological advances, genetic dysfunctions that can cause different diseases have been identified with greater sensitivity. Globally, this is the eleventh case reported of DHTKD1 gene mutation linked to CMT2Q. Moreover, this is the first case related to NTRK2 gene mutation (linked to obesity, hyperphagia, and delayed development). The patient showed an atypical CMT2Q phenotype additional to obesity. Therefore, we propose to study metabolic disorders linked to hereditary peripheral neuropathies.

Introducción: La enfermedad de Charcot-Marie-Tooth tipo 2Q (CMT2Q) es una alteración poco frecuente (< 1/1,000,000 habitantes en todo el mundo) condicionada por mutaciones en el gen DHTKD1, localizado en el cromosoma 10p14. El padecimiento inicia en la adolescencia o la edad adulta de manera lenta y progresiva, con debilidad muscular y atrofia distal simétrica, y afecta predominantemente las extremidades inferiores y los reflejos tendinosos profundos, que se encuentran reducidos o ausentes. Solo se ha reportado un caso familiar de ocho personas afectadas con la mutación aislada en el gen DHTKD1 y un caso familiar de dos personas afectadas con mutaciones en los genes DHTKD1 y GJB1, ambas familias de China. Caso clínico: Se presenta el caso de un paciente de sexo masculino de 10 años y 11 meses de edad con obesidad, caídas frecuentes, edema de miembros pélvicos y dolor en las extremidades inferiores y superiores. Se realizaron valoración clínica y estudio genético molecular de exoma dirigido, el cual reportó mutaciones en los genes DHTKD1 y NTRK2. Conclusiones: Gracias al avance científico y tecnológico se han podido identificar con mayor precisión las alteraciones genéticas causantes de diferentes enfermedades. Este es el undécimo caso reportado en el mundo de una mutación en el gen DHTKD1 asociada con la enfermedad de CMT2Q. También es el primer caso relacionado con una mutación del gen NTRK2 (asociada con obesidad, hiperfagia y retraso en el desarrollo). El paciente presentó un cuadro clínico atípico de enfermedad de CMT2Q agregado a obesidad. Por ello, se sugiere estudiar a fondo la conexión entre trastornos metabólicos y neuropatías periféricas hereditarias.

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Diagnostic yield of genetic studies for Charcot-Marie-Tooth disease (CMT) is little known, with a lack of epidemiological data to build better diagnostic strategies outside the United States and Europe. We aimed to evaluate the performance of two molecular diagnostic strategies for patients with CMT, and to characterize epidemiological findings of these conditions in southern Brazil. We performed a single-center cross-sectional study, in which 94 patients (55 families) with CMT suspicion were evaluated. Overall, the diagnostic yield of the combined strategy of Multiplex-ligation-dependent-probe-amplification (MLPA) of PMP22/GJB1/MPZ and GJB1/MPZ/PMP22 Sanger sequencing was 63.6% (28/44) for index cases with demyelinating/intermediate CMT suspicion (21 CMT1A-PMP22, 5 CMTX1-GJB1 and 2 with probably CMT1B-MPZ diagnosis). Five of the 11 index cases (45.4%) with axonal CMT had at least a possible diagnosis with next generation sequencing (NGS) panel of 104 inherited neuropathies-related genes (one each with CMT1A-PMP22, CMT2A-MFN2, CMT2K-GDAP1, CMT2U-MARS, CMT2W-HARS1). Detailed clinical, neurophysiological and molecular data of families are provided. Sequential molecular diagnosis strategies with MLPA plus target Sanger sequencing for demyelinating/intermediate CMT had high diagnostic yield, and almost half of axonal CMT families had at least a possible diagnosis with the comprehensive NGS panel. Most frequent subtypes of CMT in our region are CMT1A-PMP22 and CMTX1-GJB1.

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Herein, we report a patient that presented with late-onset progressive steppage gait, neuropathy and pes cavus, suggesting Charcot-Marie-Tooth (CMT) disease. Subsequent genetic investigation confirmed Friedreich's ataxia (FRDA). We demonstrate that late-onset Friedreich's ataxia (LOFA) may be a CMT mimicker. This case reinforces that other genetic conditions may clinically resemble CMT. The clinical similarities between CMT and FRDA include a symmetrical neuropathy (axonal in FRDA), steppage gait, and eventually scoliosis. We suggest that late-onset forms of hereditary neuropathies should be carefully evaluated, since LOFA may be a CMT mimicker.

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BACKGROUND: Charcot-Marie-Tooth disease (CMT) is the most common inherited neuropathy. CMT is classified into 2 main subgroups: CMT type 1 (CMT1; demyelinating form) and CMT type 2 (CMT2; axonal form). The objectives of this study were to systematically review and assess the quality of studies reporting the incidence and/or prevalence of CMT worldwide. SUMMARY: A total of 802 studies were initially identified, with only 12 meeting the inclusion criteria. CMT prevalence was reported in 10 studies and ranged from 9.7/100,000 in Serbia to 82.3/100,000 in Norway. The frequency of the main subtypes varied from 37.6 to 84% for CMT1 and from 12 to 35.9% for CMT2; the country with the lowest prevalence of CMT1 was Norway, and the country with the highest prevalence of CMT1 was Iceland; on the other hand, CMT2 was least prevalent in the United Kingdom and most prevalent in Norway. KEY MESSAGES: This review reveals the gaps that still exist in the epidemiological knowledge of CMT around the world. Published studies are of varying quality and utilise different methodologies, thus precluding a robust conclusion. Additional research focusing on epidemiological features of CMT in different nations and different ethnic groups is needed.

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A different and rare type of atrophy with a predominant pattern in scapulo-peroneal distribution was described by Davidenkow in 1939. The syndrome was characterized by some researchers as a variant of Charcot-Marie-Tooth disease, however Davidenkow noticed that clinical and laboratorial manifestations did not corroborate exactly with this hypothesis. We describe a case of a female patient, 39 years-old, clinical picture similar to the syndrome described by Davidenkow, presenting scapulo-peroneal atrophy. Her first symptoms had appeared when she was 24, initially with proximal motor weakness in the upper limbs. This patient did not have family history of myopathy or neuropathy. Several tests were performed to exclude other syndromes that could be included in the differential diagnosis, by testing gene mutation, in addition to the physical examination and electromyography. The large spectrum of neuromuscular diseases makes difficult the diagnosis of Davidenkow's syndrome which always should be considered in the differential diagnosis.

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En 1939 Davidenkow describió un tipo de atrofia diferente y rara con un patrón predominante en distribución escápulo-peroneal. Algunos investigadores caracterizaron el síndrome como una variante de la enfermedad de Charcot-Marie-Tooth; sin embargo, Davidenkow percibió que las manifestaciones clínicas y de laboratorio no corroboraban exactamente esta hipótesis. Describimos el caso de una mujer de 39 años, con cuadro clínico semejante al síndrome descrito por Davidenkow, presentando atrofia escápulo-peroneal. Sus primeros síntomas comenzaron cuando tenía 24 años, inicialmente con debilidad motora proximal en los miembros superiores. No tenía historia familiar de miopatía o neuropatía y se excluyeron otros síndromes que se podrían incluir entre los diagnósticos diferenciales mediante la realización de pruebas de mutación genética, además del examen físico y electromiografía. El amplio espectro de enfermedades neuromusculares a veces dificulta su diagnóstico y debe ser siempre considerado en el diagnóstico diferencial.

A different and rare type of atrophy with a predominant pattern in scapulo-peroneal distribution was described by Davidenkow in 1939. The syndrome was characterized by some researchers as a variant of Charcot-Marie-Tooth disease, however Davidenkow noticed that clinical and laboratorial manifestations did not corroborate exactly with this hypothesis. We describe a case of a female patient, 39 years-old, clinical picture similar to the syndrome described by Davidenkow, presenting scapulo-peroneal atrophy. Her first symptoms had appeared when she was 24, initially with proximal motor weakness in the upper limbs. This patient did not have family history of myopathy or neuropathy. Several tests were performed to exclude other syndromes that could be included in the differential diagnosis, by testing gene mutation, in addition to the physical examination and electromyography. The large spectrum of neuromuscular diseases makes difficult the diagnosis of Davidenkow’s syndrome which always should be considered in the differential diagnosis.

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The aim of this study was to evaluate the pulmonary condition in a large family with Charcot-Marie-Tooth disease type 2 (CMT2). Eighteen participants diagnosed with CMT2 and 20 healthy individuals were evaluated by spirometry and maximal expiratory and maximal inspiratory pressures (MEP and MIP, respectively). Clinical disability was measured with CMT neuropathy score (CMTNS; range 0-36). One control group (CG) comprising 20 individuals, matched for age, sex and body mass index, were used for comparison. Eight patients were female (44.5%) and 10 patients were male (55.5%); mean age was 31.8 years (range 11-79) and CMTNS range was 6-26. Differences between CMT2 and CG in the spirometry and respiratory muscle strength were statistically significant for all dimensions. There were significant correlations between CMTNS and MIP (Pearson = -0.581) and MEP (Pearson = -0.5090). The results of this study show that patients with CMT, in spite of not showing clinical signs of advanced respiratory impairment, may present subclinical respiratory changes. The respiratory comprise in the CMT disease can be silent and insidious without presenting characteristic clinical signals.

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A paresia distal crural, muito marcante nos pacientes com doença de Charcot-Marie-Tooth (CMT), provoca inúmeras alterações nos padrõesda marcha. Vários recursos de reabilitação têm sido propostos para gerenciar os problemas de deambulação, entre eles a utilização de órteses tornozelo-pé (OTP). O objetivo deste trabalho foi analisar efeitos imediatos do uso de OTP na cinemática da marcha e nos parâmetros estabilométricos em paciente com CMT. Buscou-se avaliar: o equilíbrio e a marcha, por meio da Escala de Avaliação da Mobilidade Orientada pelo Desempenho (POMA); a cinemática da marcha, com o sistema Qualisys Track Manager (QTM); e a estabilometria, utilizando a plataforma de força. As avaliações foram realizadas antes e durante o uso de OTP. Observou-se declínio na escala POMA durante o uso da OTP de 11%. Na cinemática da marcha, verificou-se decréscimo na velocidade e comprimento da passada, assim comoaumento na duração dela. Na estabilometria, observou-se aumento na velocidade médio-lateral e na velocidade média na condição sem restrição visual, e aumento em todos os parâmetros de velocidade e deslocamento na condição com restrição visual durante o uso da OTP. O paciente avaliado não apresentou melhoras imediatas com aplicação de OTP, fato justificado pela presença de contraturas e tempo de evolução da doença. A prescrição de órteses na CMT deve respeitar as particularidades do paciente e a forma de apresentação da patologia.

The distal crural weakness, very striking in patients with Charcot-Marie-Tooth disease (CMT), causes gait impairment. Several rehabilitationapproaches have been proposed to manage the ambulation problems, among them, the use of ankle-foot orthosis (AFO). The objective of this study is to analyze the immediate effects of using AFO in the gait kinematic and stabilometric parameters in a patient with CMT. We evaluated the balance and the gait using Performance Oriented Mobility Assessment (POMA) Scale, gait kinematics using the Qualisys Track Manager (QTM) system and stabilometry, using a force platform. The evaluations were performed before and during the use of AFO. A decreasing of POMA scores was observed when the patient used AFO (11%). In the gait kinematic a decrease was verified in the speed gait and step length, as an increase in the time. In the stabilometry was observed an increase in the mediolateral velocity and average velocity in the condition without visual restrictionand an increase in all parameters of velocity and displacement in thecondition with visual restriction during the use of the AFO. The assessedpatient didn?t present immediate improvement with the AFO due to contractures presented and the time of the disease course. Prescription of orthosis in the CMT should respect the patient?s particularities and the clinical manifestations, and the way the pathology is presented.

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Pmp-22 mutant mice (Trembler-J: B6.D2-Pmp22/J), are used as a model to study Charcot-Marie-Tooth type 1A (CMT1A). The identification of individual genotypes is a routine in the management of the Tr(J) colony. The earliest phenotypic manifestation of the pmp-22 mutation is just about 20th postnatal days, when pups begin to tremble. In this study, a rapid and simple diagnostic method was developed by modifying the Tail Suspension Test (MTST) to determine the difference between the Tr(J) and the wild-type mice phenotype. The animal behavioral phenotypes generated during the test were consistent with the specific genotype of each animal. The MTST allowed us to infer the heterozygous genotype in early postnatal stages, at 11 days after birth. The motor impairment of Tr(J) mice was also analyzed by a Fixed Bar Test (FBT), which revealed the disease evolution according to age. The main advantages of MTST are its objectivity, simplicity, and from the viewpoint of animal welfare, it is a non-invasive technique that combined with his rapidity show its very well applicability for use from an early age in these mice.

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Compound forms of Charcot-Marie-Tooth (CMT) disease have been recently associated with unusually severe neuropathies, an observation that prompted the proposition that the additive effects of two mutations should be searched in patients whose clinical severity falls outside the common CMT phenotypes. In this report, we present a father and a daughter with a very mild and unusual disease that segregates with two mutations in PMP22 gene, the 17p11.2-p12 duplication and a Ser72Leu point mutation. We propose that the deleterious effects of each mutation are partially compensated by the functional effect of the other.

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Frecuency of the allele causing the axonal form of autosomal recessive Charcot-Marie-Tooth in Palmares, Costa Rica. The Charcot-Marie-Tooth disease constitutes is among the most frequent hereditary peripheral neuropathies world-wide. We identified a family from Palmares (Alajuela, Costa Rica) with 18 affected members. Their neuropathy is axonal, with an autosomal recessive pattern of inheritance; the responsible gene is at the 19q13.33 chromosomal region. Later the mutation was identified in gene MED25. We studied the frequency and geographic distribution of the mutant allele. In a random sample of 103 individuals, six were heterozygote and were widely distributed in Palmares. There was no person in homozigote state for the mutant allele. Clinical characteristics do not differ significantly between individuals that are homozygous for the wildtype allele and individuals hetero zygous for the mutation. A 5.83 % of the population is heterozygote and the frequency of the Ala335Val allele is 0.029, six times higher than in a sample of the Costa Rican population. Werecommend a molecular analysis of carriers to detect additional cases in the region. Rev. Biol. Trop. 57 (Suppl.1): 381-387. Epub 2009 November 30.

La enfermedad de Charcot-Marie-Tooth constituye elgrupo de neuropatías periféricas hereditarias más común a nivel mundial. Una familia con 18 afectados del cantón de Palmares (Alajuela, Costa Rica) con una neuropatía de tipo axonal y herencia autosómica recesiva, permitió localizar el gen responsable en la región 19q13.33. Posteriormente se identificó la mutación causante en el gen MED25. El presente estudio determinó la frecuencia del alelo mutante, así como la distribución geográfica de este alelo. En una muestra al azar de 103 individuos se encontraron seis individuos heteroigotas para la mutación, distribuidos por todo el cantón. No se encontró ninguna persona en estado homocigota para este alelo. No hallamos algunacaracterística clínica que difiera significativamente entre los individuos homocigotos silvestres y los heterocigotos para la mutación. El 5.83% de la población es heterocigota y la frecuencia del alelo Ala335Val es de 0.029, seis veces mayor que en una muestra de toda la población costarricense. Por esta razón se recomienda un análisis molecular de portadores con el fin de alertar sobre la posibilidad de aparición de más casos en el cantón.

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Objetivo: Evaluar la distribución espacial como indicador de la incidencia de la enfermedad de Charcot-Marie-Tooth por los egresos hospitalarios reportados en Costa Rica entre el período 1990-2003. Métodos: Se aplicó un rastreo estadístico espacial de la incidencia de la enfermedad y se evaluó la significancia estadística de los conglomerados con excesos de casos. Resultados: El exceso de casos observados de la enfermedad en la zona de Naranjo fue estadísticamente significativo (56 versus 26.3 p menor 0.05). Otras regiones en donde se presenta exceso significativo de casos de CMT, son: Tibás (33 versus 13.5), Alajuela Centro (20 versus 6), Turrialba centro (16 versus 4.5), Golfito (18 versus 5.6) y Puntarenas centro (9 versus 1.5). Discusión: Se propone este rastreo estadístico espacial como herramienta en el proceso de toma de decisiones paa disminuir la incidencia de la enfermedad, así como atender adecuadamente a los afectados por CMT y sus familias, pues el métoido identificó regiones críticas o conglomerados (clusters) en donde es necesario dirigir los esfuerzos para la evaluación de la incidencia de la enfermedad.

Objective: To evaluate the spatial distribution of Charcot- Marie-Tooth disease as indicator of incidence in Costa Rica between 1990-2003.Methods: A spatial statistical scan was performed for the CMT incidence. We evaluated the statistical significance of high rate clusters. Results: The excess of observed cases of the disease in the area of Naranjo was statistically significant (56 vs. 26.3 p <0.05). Other regions showing significant excess of cases of CMT are: Tibás (33 vs. 13.5), Alajuela Centro (20 vs. 6), Turrialba Centro (16 vs. 4.5), Golfito (18 vs. 5.6) and Puntarenas Centro (9 vs. 1.5).Discussion: Spatial statistical scan is proposed as a tool in the decision making process in order to reduce the incidence of the disease and respond appropriately to those affected by CMT and their families. The method identifies clusters where it is necessary to focus efforts in evaluating the incidence of the disease.

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