Clinical, pathological and genetic characteristics of 8 patients with distal hereditary motor neuropathy / 北京大学学报(医学版)

OBJECTIVE@#Distal hereditary motor neuropathy (dHMN) comprises a heterogeneous group of inherited disorders associated with neurodegeneration of motor nerves and neurons, mainly charac-terized by progressive atrophy and weakness of distal muscle without clinical or electrophysiological sensory abnormalities. To improve the recognition and diagnosis of the disease, we summarized the clinical manifestations, electrophysiological, pathological, and genetic characteristics in eight patients with dHMN.@*METHODS@#Eight probands from different families diagnosed with dHMN were recruited in this study between June 2018 and April 2019 at Peking University People's Hospital. Eight patients underwent complete neurological examination and standard electrophysiological examinations. The clinical criteria were consistent with the patients presenting with a pure motor neuropathy with no sensory changes on electrophysiology. The detailed clinical symptoms, neurophysiological examinations, pathological features and gene mutations were analyzed retrospectively. Genetic testing was performed on the eight patients using targeted next-generation sequencing panel for inherited neuromuscular disorder and was combined with segregation analysis.@*RESULTS@#The age of onset ranged between 11 and 64 years (median 39.5 years) in our dHMN patients. All the cases showed a slowly progressive disease course, mainly characterized by distal limb muscle weakness and atrophy. The motor nerve conduction revealed decreased compound muscle action potential amplitude and velocity, while the sensory nerve conduction velocities and action potentials were not affected. Needle electromyography indicated neurogenic chronic denervation in all patients. Muscle biopsy performed in two patients demonstrated neurogenic skeletal muscle damage. Sural nerve biopsy was performed in one patient, Semithin sections shows relatively normal density and structure of large myelinated fibers, except very few fibers with thin myelin sheaths, which suggested very mild sensory nerve involvement. Eight different genes known to be associated with dHMN were identified in the patients by next-generation sequencing, pathogenic dHMN mutations were identified in three genes, and the detection rate of confirmed genetic diagnosis of dHMN was 37.5% (3/8). Whereas five variants of uncertain significance (VUS) were identified, among which two novel variants co-segregated the phenotype.@*CONCLUSION@#dHMN is a group of inherited peripheral neuropathies with great clinical and genetic heterogeneity. Next-generation sequencing is widely used to discover pathogenic genes in patients with dHMN, but more than half of the patients still remain genetically unknown.

Neuropatía hereditaria con susceptibilidad a la parálisis por presión: importancia del protocolo electrodiagnóstico / Hereditary neuropathy with liability to pressure palsies. Importance of electrodiagnostic protocol

Introduction: Hereditary neuropathy with susceptibility to pressure palsy is a genetic disorder of autosomal dominant inheritance that affects mainly the peripheral nerve myelin. This work aims to give a detailed description of a peculiar case and a literature review. Method: Neurophysiological and genetic study of 21 years old patient referred to the Clinical Neurophysiology Unit, by paresthesia in the right ulnar nerve territory. Results: Electromyographic examination demonstrated the existence of a sensory-motor polineuropathy greater intensity in multiple locations susceptible to nerve entrapment and genetic study confirmed the existence of a deletion at the PMP22 gene (chromosome 17p11.2). Conclusions: Hereditary neuropathy with susceptibility to pressure palsy is an underdiagnosed disease that may go unnoticed by simulating a simple compressive neuropathy. A rigorous neurophysiological study is essential to carry out a suspected diagnosis and to guide subsequent genetic diagnosis.

Introducción: La neuropatía hereditaria con susceptibilidad a la parálisis por presión es un trastorno genético de herencia autosómica dominante que afecta principalmente a la mielina de los nervios periféricos. Con este trabajo se pretende por un lado hacer una descripción detallada de un caso peculiar resaltando la importancia del protocolo electrodiagnóstico además de realizar una revisión bibliográfica sobre el tema. Método: Estudio neurofisiológico y genético de paciente de 21 años remitido a la Unidad de Neurofisiología Clínica por parestesias en territorio del nervio cubital derecho. Resultados: La exploración electromiográfica objetivó la existencia de una polineuropatía sensitivo-motora de predominio desmielinizante y mayor intensidad en localizaciones susceptibles al atrapamiento nervioso y el estudio genético confirmó la existencia de una deleción a nivel del gen PMP22 (cromosoma 17p11.2). Conclusiones: La neuropatía hereditaria con susceptibilidad a la parálisis por presión es una enfermedad infradiagnosticada que puede pasar desapercibida simulando una simple neuropatía compresiva. Un riguroso estudio neurofisiológico es fundamental para llevar a cabo un diagnóstico de sospecha así como para orientar el posterior diagnóstico genético.

Autosomal dominant HMSN with proximal involvement: new Brazilian cases / HMSN autossômica dominante com envolvimento proximal: novos casos brasileiros

We report four Brazilian siblings with Autosomal Dominant Hereditary Motor Sensory Neuropathy with Proximal Dominant Involvement (HMSN-P), a rare form of HMSN, that was characterized by proximal dominant muscle weakness and atrophy onset after the age of 30 years, fasciculation, arreflexia and sensory disturbances with autosomal dominant inheritance. Electrophysiological study and sural nerve biopsy were in the accordance with axonal sensory motor polyneuropathy and laboratorial analysis disclosed serum lipids and muscle enzymes abnormalities. Our report is the first done by a group outside Japan, where the disease initially seemed to be restricted and stressed the phenotypic variability from the original report.

Relatamos os casos de quatro irmãos brasileiros com Neuropatia Sensitivo Motora Hereditária com Envolvimento Proximal Dominante (HMSN-P), uma forma rara de HMSN caracterizada por fraqueza muscular de predomínio proximal e atrofia de instalação após os 30 anos, fasciculações, arreflexia, distúrbios sensitivos e padrão de herança autossômica dominante. Os estudos eletrofisiológicos e de biópsia do nervo sural confirmaram o diagnóstico de polineuropatia sensitivo-motora com padrão lesional axonal. Laboratorialmente foram constatadas anormalidades séricas no metabolismo lipídico e enzimas musculares. Nosso relato é o primeiro feito por um grupo fora do Japão, onde a doença parecia restrita até então e ressalta a variabilidade fenotípica apresentada nos casos Brasileiros.

Neuropatía hereditaria con predisposición a la parálisis por compresión: presentación de casos clínicos y electrofisiológicos / Hereditary neuropathy with liability to pressure palsies: presentation of clinical and electrophysiological cases

Hereditary neuropathy with liability to pressure palsies (HNPP) is a rare autosomal dominant neuropathy characterized by recurrent episodes of painless multiple nerve entrapments. We present five cases of HNPP confirmed by clinical and electrophysiological studies. Genetic confirmation of the diagnosis was performed in only one of the cases, given the fact that there are no laboratories performing this test inChile. This emphasizes the importance of electrophysiological diagnostic suspicion and the need for electrophysiological studies in family members even when asymptomatic.

Actualidad génetica y clínica en las polineuropatías sensoromotoras hereditarias / Genetic present time and clinic in thehereditary motor sensory polineuropathies

Como objetivo hemos tenido el ampliar el conocimiento en el tema de las polineuropatías sensorimotoras hereditarias y mostrar los aportes de la genética molecular en la clasificación de esta enfermedad. En el desarrollo, revisamos el tema de las polineuropatías sensorimotoras hereditarias partiendo desde sus primeras descripciones. Se hace énfasis en la generalidad del cuadro clínico, seleccionando inicialmente la clasificación de Dyck & Lambert para luego detallar el gran paso generado por los avances de la genética molecular en la clasificación exacta de este grupo de desórdenes de los nervios periféricos. Se establece como regla para clasificarlo la naturaleza de la polineuropatía, dividiéndola en Desmielinizante y Axonal. En cada uno de estos dos grupos se explica claramente el patrón de herencia (A. Dominante, A recesiva, Ligada al Cromosoma X) con sus respectivas mutaciones y productos proteicos alterados.Las neuropatías sensorimotoras son un gran síndrome, en el cual la existencia de múltiples mutaciones explica la gran variabilidad en el cuadro clínico y en la expresión de esta enfermedad. El diagnóstico exacto de estas neuropatías parece estar muy ligado a la genética molecular, por lo que la clasificación de Dyck y Lambert es la de mayor utilidad para una correcta interpretación clínica de este síndrome

Hereditary motor and autonomic neuronopathy 1 maps to chromosome 20q13.2-13.3

The spinal muscular atrophies (SMA) or hereditary motor neuronopathies result from the continuous degeneration and death of spinal cord lower motor neurons, leading to progressive muscular weakness and atrophy. We describe a large Brazilian family exhibiting an extremely rare, late-onset, dominant, proximal, and progressive SMA accompanied by very unusual manifestations, such as an abnormal sweating pattern, and gastrointestinal and sexual dysfunctions, suggesting concomitant involvement of the autonomic nervous system. We propose a new disease category for this disorder, `hereditary motor and autonomic neuronopathy', and attribute the term, `survival of motor and autonomic neurons 1' (SMAN1) to the respective locus that was mapped to a 14.5 cM region on chromosome 20q13.2-13.3 by genetic linkage analysis and haplotype studies using microsatellite polymorphic markers. This locus lies between markers D20S120 and D20S173 showing a maximum LOD score of 4.6 at D20S171, defining a region with 33 known genes, including several potential candidates. Identifying the SMAN1 gene should not only improve our understanding of the molecular mechanisms underlying lower motor neuron diseases but also help to clarify the relationship between motor and autonomic neurons.

Hereditary neuropathy with liability to pressure palsies (HNPP) patients of Korean ancestry with chromosome 17p11.2-p12 deletion

Hereditary neuropathy with liability to pressure palsies (HNPP) is an autosomal dominant inherited disorder characterized by recurrent pressure palsies. Most HNPP patients have a 1.5 mb deletion in chromosome 17p11.2-p12. The present study aimed at evaluating the deletion of the 17p11.2-p12 region in Korean subjects with families exhibiting HNPP phenotype, and to determine the clinical, electrophysiological and morphological aspects specifically associated with this deletion in HNPP patients. By genotyping six microsatellite markers (D17S921, D17S955, D17S1358, D17S839, D17S122 and D17S261), HNPP with the deletion was observed in 79% (19 of 24) of HNPP families. Nerve conduction studies were performed in 35 HNPP patients from these 19 families. The observed HNPP deletion frequency in Koreans is consistent with findings in other populations. Disease onset occurred at a significantly earlier age in patients with recurrent pressure palsies than in those with a single attack (P<0.01). Nerve conduction studies demonstrated diffuse mild to moderate slowing of nerve conduction velocities that were worse over the common entrapment sites, regardless of the clinical manifestations. A long duration of compound muscle action potentials without a conduction block or a temporal dispersion is a characteristic of this disease. A sural nerve biopsy with teasing was performed in four patients, and tomacula of the myelin sheath was found in 56.4%. Our findings appear to support the existence of a phenotype/genotype correlation in HNPP patients of Korean ancestry with the deletion, and suggest that HNPP patients with earlier symptom onset face an increased chance of having recurrent attacks.

Rapid Detection of Duplication/Deletion of the PMP22 Gene in Patients with Charcot-Marie-Tooth Disease Type 1A and Hereditary Neuropathy with Liability to Pressure Palsy by Real-time Quantitative PCR using SYBR Green I Dye

Mutations and altered gene dosage of the peripheral myelin protein (PMP22) gene in chromosome 17p11.2-12 are the main causes for hereditary neuropathies, accounting for approximately 70% of all cases. Patients with duplication of the PMP22 develop Charcot-Marie-Tooth disease type 1A (CMT1A) and deletion of one PMP22 allele leads to hereditary neuropathy with liability to pressure palsy (HNPP). Twenty patients with CMT1A, 17 patients with HNPP, and 18 normal family members and 28 normal controls were studied by real-time quantitative PCR using SYBR Green I on the ABI 7700 Sequence Detection System. The copy number of the PMP22 gene was determined by the comparative threshold cycle method and the albumin was used as a reference gene. The PMP22 duplication ratio ranged from 1.45 to 2.06 and the PMP22 deletion ratio ranged from 0.42 to 0.64. The PMP22 ratio in normal controls, including normal family members, ranged from 0.85 to 1.26. No overlap was found between patients with CMT1A or patients with HNPP and normal controls. This method is fast, highly sensitive, specific, and reproducible in detecting PMP22 duplication and deletion in CMT1A and HNPP patients, respectively.

Hereditary motor and sensory neuropathy with congenital glaucoma

We report three siblings of a family with hereditary motor and sensory plyneuropathy (HMSN) and buphthalmos. Eletrophysiological studies showed a demyelinating neuropathy and pathological findings showed severe loss of myelinated fibers (MF), thin myelin sheaths and myelin infoldings in a few remaining MF. The presumed mode of inheritance is autosomal recesive. This family probably represents an unique form of CMT4 that may be related to one of the congenital glaucoma genic locus, particularly GLC3A and GLC3B, described in Turkish families.

La neuropatía sensitiva motora hereditaria: un artículo de revisión bibliográfica / The hereditary sensitive motors neuropaties: a bibliograpic review of article

En este trabajo se hace una descripción didáctica de un grupo de neuropatías englobadas en el término de neuropatías sensitivas motoras hereditarias. Después de dar datos para el diagnóstico de los 7 tipos presentes se analiza la enfermedad de Charcot Marie Tooth como la más frecuente, desde el punto de vista diagnóstico, patogénico y de tratamiento

Neuropatía amiloidea hereditaria: forma predominantemente disautonómica / Hereditary amyloid neuropathy with dysautonomic dysfunction

Presentamos un paciente de 38 años, quien consultó por presentar desde 6 años antes impotencia sexual, diarrea, hipotensión postural y parestesias en miembros inferiores. Tenía antecedentes familiares de cuadros similares. El diagnóstico clínico de neuropatía amiloidea hereditaria fue sospechado frente a una neuropatía periférica, con disautonomía y antecedentes familiares. La biopsia de nervio periférico confirmó el diagnóstico. Nosotros nos preguntamos si la disfunción disautonómica tan severa de nuestro paciente es otra variedad de neuropatía amiloidea hereditaria o sólo una variante del tipo I de Corino Andrade

Familial spastic paraplegia.

Familial spastic paraplegia (FSP) was recorded in three families. The pattern of familial transmission and the onset in the second and third decade of life strongly suggested autosomal dominant inheritance. FSP in this series showed the consistent, classical, clinical features with some inconstant findings (nystagmus, dysarthria, posterior column involvement). Baclofen for the treatment of spasticity is beneficial in this condition and genetic counselling should be considered.