RESUMEN
<p><b>OBJECTIVE</b>To examine mitochondrial DNA mutations in mitochondrial myopathy.</p><p><b>METHODS</b>Three suspected cases of mitochondrial myopathy were examined by HE staining, histochemical staining methods and electron microscopy. The mutations in all 22 tRNA genes of mitochondrial genome were screened by polymerase chain reaction-single strand conformation polymorphism and DNA sequencing.</p><p><b>RESULTS</b>The three cases were diagnosed as mitochondrial myopathy. The examinations revealed that patient 1 had a homoplasmic A1627G mutation in tRNA-Val gene, and patient 2 had a heteroplasmic A1627G/A mutation in tRNA-Val gene, and patient 3 had two mutationsuone was homoplasmic T5554C mutation in tRNA-Trp gene, the other was heteroplasmic A10412C/A mutation in tRNA-Arg gene.</p><p><b>CONCLUSION</b>tRNA genes mutations of mtDNA might be one of the etiologies of mitochondrial myopathy.</p>
Asunto(s)
Adulto , Femenino , Humanos , Masculino , Adulto Joven , Análisis Mutacional de ADN , ADN Mitocondrial , Química , Genética , Microscopía Electrónica de Transmisión , Miopatías Mitocondriales , Genética , Patología , Fibras Musculares Esqueléticas , Metabolismo , Patología , Mutación , Reacción en Cadena de la Polimerasa , Polimorfismo Conformacional Retorcido-Simple , ARN de Transferencia de Valina , GenéticaRESUMEN
<p><b>OBJECTIVE</b>To investigate the D4Z4 repeats on chromosome 4q35 in normal individuals in Shanghai and analysis the polymorphism of the D4Z4 locus.</p><p><b>METHODS</b>The length of D4Z4 repeats on chromosome 4q35 in 191 normal individuals in Shanghai was determined by pulsed-field gel electrophoresis and Southern blotting after double digestion with Eco RI and Bln I. The number of short D4Z4 repeats was counted after partial digestion with Kpn I.</p><p><b>RESULTS</b>Among 191 normal individuals in Shanghai, seventeen showed the size of D4Z4 fragments ranged from 22 to 34 kb, i.e. 8.9% of individuals had fewer numbers of D4Z4 repeats. Of these 17 individuals, sixteen showed the short D4Z4 fragment on chromosome 4q35, and one low D4Z4 fragment was correlated to 4q35--> 10q26 translocation.</p><p><b>CONCLUSION</b>The frequency of individuals having fewer numbers of D4Z4 repeats on chromosome 4q35 in Shanghai population is higher than that in Caucasian population although the short D4Z4 fragment on chromosome 4q35 is associated with facioscapulohumeral muscular dystrophy. These findings suggest that other factors may also contribute to facioscapulohumeral muscular dystrophy.</p>