Single muscle fiber analysis of myoclonus epilepsy with ragged-red fibers

✍ Scribed by Shuji Mita; Makoto Tokunaga; Eiichiro Uyama; Toshihide Kumamoto; Kazutoshi Uekawa; Makoto Uchino

• Book ID: 102652946
• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 691 KB
• Volume: 21
• Category: Article
• ISSN: 0148-639X
• DOI: 10.1002/(sici)1097-4598(199804)21:4<490::aid-mus7>3.0.co;2-4

✦ Synopsis

We examined two muscle biopsy specimens from a proband and her mother with myoclonus epilepsy with ragged-red fibers (MERRF), both obtained at an interval of about 10 years, using histochemistry, in situ hybridization, and single-fiber polymerase chain reaction. Total (wild-type and mutant) mitochondrial DNAs (mtDNAs) were greatly increased in ragged-red fibers (RRF) over non-RRF in all muscle specimens analyzed. The proportion of mutant mtDNA was also significantly higher in RRF than in non-RRF. By comparing the first and second muscle biopsied specimens in each patient, we found that while the proportion of RRF, cytochrome c oxidase deficient fibers, and mutant DNA in muscle changed over a 10-year period, the proportion of wild-type and mutant mtDNAs in RRF and in non-RRF was similar between the two specimens. These results suggest that the ratio of wild-type to mutant mtDNAs in RRF and non-RRF in MERRF is at a steady state level in each muscle fiber, without replicative advantage of mutant mtDNA.