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Gene deletions in Japanese patients with Duchenne and Becker muscular dystrophy
J Asano1, S Tomatsu, K Sukegawa
1Department of Pediatrics, Gifu University, School of Medicine, Japan.
Abstract:
Thirty-eight unrelated Japanese patients with Duchenne and Becker muscular dystrophy (DMD and BMD) have been investigated with the DMD cDNA probes. The 14-kb DMD cDNA was subdivided into 6 subclones and HindIII-digested DNAs were analyzed by Southern blotting. Out of 38 unrelated patients, 14 showed a deletion of one or several of the exon-containing HindIII fragments (36.8%). These corresponded to 50% (9/18) of BMD patients and 25% (5/20) of DMD patients, and the position and extent of deletions were mapped and proved to be more heterogeneous in DMD than in BMD. Both ends of deletions detected in probe 1-2a were common to all six BMD patients without the maintenance of reading frame of messenger RNA, and 5' ends of deletions in probe 5b-7 were also common but maintained in frame in three BMD patients. The phenotypic-specific deletion in Japanese BMD patients has existed in the 5' end of the DMD gene, although its apparently similar deletion produced a wide range of clinical courses (BMD phenotype). There was no tight correlation between clinical severity and presence or absence of deletion in DMD or BMD.
Insights
Genetic deletions in the DMD gene were found in 36.8% of Japanese patients with Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD). Deletion patterns varied between DMD and BMD, with specific deletions linked to BMD phenotypes.
Area of Science:
- Genetics
- Molecular Biology
- Neurology
Background:
- Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) are allelic inherited neuromuscular disorders caused by mutations in the dystrophin gene.
- Genetic analysis is crucial for understanding the molecular basis and clinical variability of these dystrophinopathies.
Purpose of the Study:
- To investigate the spectrum and characteristics of DMD gene deletions in Japanese patients with DMD and BMD.
- To correlate specific deletion patterns with disease phenotypes and clinical severity.
Main Methods:
- Southern blot analysis using six subclones of the 14-kb DMD cDNA probe.
- Analysis of HindIII-digested DNA from 38 unrelated Japanese patients (18 BMD, 20 DMD).
- Mapping of deletion endpoints and assessment of reading frame maintenance.
Main Results:
- Fourteen out of 38 patients (36.8%) exhibited deletions in the DMD gene.
- Deletions were more frequent in BMD patients (50%) than in DMD patients (25%).
- Deletion patterns were more heterogeneous in DMD than in BMD. Specific deletions at the 5' end of the DMD gene were observed in BMD patients, influencing reading frame maintenance and clinical presentation.
Conclusions:
- A significant proportion of Japanese DMD and BMD patients harbor deletions in the DMD gene.
- Specific deletion characteristics, particularly at the 5' end, are associated with BMD phenotypes in Japanese populations.
- No tight correlation was found between deletion presence/absence and clinical severity in either DMD or BMD.