[Molecular genetics of myotonic dystrophy].
The gene for myotonic dystrophy (DM) was found to be an expansion of an unstable CTG repeat located in the 3'-UTR of the putative protein kinase gene. In the general population 5 approximately 37 copies of the repeat are present, but in DM patients the repeat number varies from 50 up to thousands of copies. We have determined the copy number of the CTG repeat and made a haplotype using the closely linked markers to the CTG repeat in 93 Japanese DM families. The absolute linkage disequilibrium was observed in patients from both populations, between the DM gene and the linked markers. These data strongly suggest a common origin of Caucasian and Japanese DM alleles. The genetic analysis of apparently sporadic occurrence of DM in a family in which two asymptomatic members have been shown to have a number of repeats corresponding to premutation alleles, 44 and 46 CTG alleles. These data strongly suggest that (CTG) 19 approximately 37 may act as a predisposing allele for successive DM generations and that there is a premutation allele for DM, as predicted in a multistep model for etiology of this disorder.
Miki
T
T
Department of Geriatric Medicine, Osaka University Medical School.
Yamagata
H
H
Ogihara
T
T
D000483:Alleles; D044466:Asian People; D005260:Female; D006801:Humans; D007564:Japan; D015810:Linkage Disequilibrium; D008297:Male; D009154:Mutation; D009223:Myotonic Dystrophy / Q000175:diagnosis / Q000235:genetics*; D011494:Protein Kinases / Q000235:genetics; D018911:Trinucleotide Repeats; D044465:White People
D011494:Protein Kinases