Dynamic Transcriptional Events in Distal Sural Nerve Revealed by Transcriptome Analysis

Compared with biochemical information available about the diseases in the central nervous system, that for peripheral neuropathy is quite limited primarily due to the difficulties in obtaining samples. Characterization of the core pathology is a prerequisite to the development of personalized medicine for genetically heterogeneous diseases, such as hereditary motor and sensory neuropathy (HMSN). Here, we first documented the transcriptome profile of distal sural nerve obtained from HMSN patients. RNA-seq analysis revealed that over 12,000 genes are expressed in distal sural nerve. Among them 4,000 transcripts are novel and 10 fusion genes per sample were observed. Comparing dataset from whole exome sequencing revealed that over 1,500 transcriptional base modifications occur during transcription. These data implicate that dynamic alterations are generated when genetic information are transitioned in distal sural nerve. Although, we could not find significant alterations associated with HMSN, these data might provide crucial information about the pathophysiology of HMSN. Therefore, next step in the development of therapeutic strategy for HMSN might be unveiling biochemical and biophysical abnormalities derived from those potent variation.

Frecuencia del alelo causante de la enfermedad de Charcot-Marie-Tooth (tipo axonal con herencia autosómica recesiva) en Palmares, Costa Rica / Frequency of the allele causing Charcot-Marie-Tooth disease (axonal type with autosomal recessive inheritance) in Palmares, Costa Rica

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.

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.

DNA diagnostic testing in hereditary motor and sensory neuropathies

Hereditary motor and sensory neuropathy (HMSN; Charcot-Marie-Tooth disease, CMT) was first described by Charcot and Marie in France and, independently, by Tooth in England in 1886. HMSN is the most common form of inherited motor and sensory neuropathy, and is a genetically heterogeneous disorder of the peripheral nervous system. Using positional cloning methods, the chromosomal localization (locus) of more than 40 inherited peripheral neuropathies was found in the last 15 years. However, these genetic analyses also show that many entities do not show linkage to the known loci. This issue deals with a clinical survey of inherited peripheral neuropathies regarding diagnostic approaches based on the molecular findings.

Genetics of hereditary motor and sensory neuropathy and the Costa Rican contribution: [review]

Hereditary motor and sensory neuropathy (HMSN) or Charcot-Marie-Tooth disease (CMT) is the most common hereditary illness of the peripheral nervous system. The genetics and the physiopathological aspects of the disease clarified until know, are here summarized. More than twenty genes and ten additional loci have been related with HMSN. These findings contribute to understand the metabolism of peripheral nerves and give the basis for molecular diagnostics and future therapy. Several Costa Rican families with CMT have been identified, specially with axonal forms. Two families present mutations in the myelin protein zero gene (IMPZ). In addition, linkage have been found between the disease and locus 19q13.3 in an extended family, and a mutation segregating with the disease is present in a candidate gene of the critical interval. Costa Rica has several advantages for genetical studies, that can contribute importantly in the generation of knowledge in the neurogenetical field.

Hypertrophic neuropathy with complete conduction block: hereditary motor and sensory neuropathy type III

Hypertrophic neuropathy is a non-specific consequence of repeated demyelination and remyelination, encountered in a wide range of inherited and acquired disorders. We report an 11-year-old boy with HMSN III, a kind of hypertrophic neuropathy, with clinical, electrophysiologic and pathologic data. The electrophysiologic studies show complete conduction block in the upper and lower extremities with severe abnormal spontaneous activities. The pathologic findings of sural nerve reveal prominent hypomyelination, onion bulb formation, and severe endoneurial collagenization. Complete conduction block with the preservation of fair to good grade muscle strength is an unusual finding in hypertrophic neuropathy and other peripheral neuropathies, in general.