Related Experiment Videos
[Molecular genetics of myotonic dystrophy]
T Miki1, H Yamagata, T Ogihara
1Department of Geriatric Medicine, Osaka University Medical School.
Rinsho Shinkeigaku = Clinical Neurology
|December 1, 1995
Summary
Myotonic dystrophy (DM) involves unstable CTG repeat expansions. Genetic analysis in Japanese families suggests a common origin for DM alleles across populations and identifies premutation alleles that predispose to the disorder.
Area of Science:
- Genetics
- Molecular Biology
- Human Disease Genetics
Background:
- Myotonic dystrophy (DM) is characterized by an unstable CTG repeat expansion in the 3'-UTR of a protein kinase gene.
- Normal individuals have approximately 5-37 CTG repeats, while DM patients exhibit expansions ranging from 50 to thousands of copies.
Purpose of the Study:
- To determine the CTG repeat copy number and haplotype in Japanese DM families.
- To investigate the genetic linkage between the DM gene and closely linked markers.
- To explore the potential role of premutation alleles in DM etiology and transmission.
Main Methods:
- Analysis of CTG repeat copy number in 93 Japanese DM families.
- Haplotype analysis using markers linked to the CTG repeat.
- Genetic analysis of sporadic DM cases and asymptomatic family members with premutation alleles.
Main Results:
- Strong linkage disequilibrium observed between the DM gene and linked markers in both Caucasian and Japanese populations, suggesting a common origin.
- Identification of asymptomatic individuals with premutation alleles (44 and 46 CTG repeats).
- Evidence supporting the role of (CTG) 19-37 repeats as predisposing alleles for successive DM generations.
Conclusions:
- Japanese and Caucasian DM alleles likely share a common ancestral origin.
- A premutation allele for DM exists, supporting a multistep model for the disorder's development.
- Normal repeat ranges (CTG) 19-37 may predispose individuals to developing DM in subsequent generations.