RESUMO
Hereditary myotonia caused by mutations in CLCN1 has been previously described in humans, goats, dogs, mice and horses. The goal of this study was to characterize the clinical, morphological and genetic features of hereditary myotonia in Murrah buffalo. Clinical and laboratory evaluations were performed on affected and normal animals. CLCN1 cDNA and the relevant genomic region from normal and affected animals were sequenced. The affected animals exhibited muscle hypertrophy and stiffness. Myotonic discharges were observed during EMG, and dystrophic changes were not present in skeletal muscle biopsies; the last 43 nucleotides of exon-3 of the CLCN1 mRNA were deleted. Cloning of the genomic fragment revealed that the exclusion of this exonic sequence was caused by aberrant splicing, which was associated with the presence of a synonymous SNP in exon-3 (c.396C>T). The mutant allele triggered the efficient use of an ectopic 5' splice donor site located at nucleotides 90-91 of exon-3. The predicted impact of this aberrant splicing event is the alteration of the CLCN1 translational reading frame, which results in the incorporation of 24 unrelated amino acids followed by a premature stop codon.
Assuntos
Búfalos/genética , Canais de Cloreto/genética , Músculo Esquelético/patologia , Mutação , Miotonia Congênita/veterinária , Alelos , Animais , Búfalos/metabolismo , Canais de Cloreto/metabolismo , Eletromiografia , Éxons , Feminino , Masculino , Músculo Esquelético/metabolismo , Miotonia Congênita/genética , Miotonia Congênita/patologia , Linhagem , Polimorfismo de Nucleotídeo ÚnicoRESUMO
Estudamos 6 pacientes, 2 caes e um coelho com intoxicaçao crotálica. Avaliamos a conduçao nervosa periférica sensitiva e motora, a transmissao neuro-muscular e eletromiografias. As biópsias de músculo foram processada por histoquímica. Os 6 pacientes apresentaram mononeuropatia sensitiva no nervo periférico adjacente ao local da inoculaçao do veneno e encontramos evidências histoquímicas de miopatia mitocondrial. Os defeitos da transmissao neuro-muscular foram mínimos. A maioria dos autores admite que veneno crotálico determina síndrome miastênica. Nossos achados indicam que ptose palpebral, facies miastênico e fraqueza muscular observados após acidente crotálico, correspondem provavelmente a miopatia mitocondrial, muitas vezes transitória e reversível.