title: Molecular analysis of two pre-mutations in myotonic dystrophy.
abstract: Here we report two families with myotonic dystrophy (DM) in which the asymptomatic parent proved to be in a pre-mutation state. Polymerase chain reaction (PCR) analysis of the region spanning the CTG expansion demonstrated that one father of the proband possessed (CTG)n repeats of n = 12 and 44 copies and the other of 15 and 47. Clinical examination showed no definite signs of DM in these two men. Haplotype analysis of DNA markers close to the DM protein kinase (DMPK) gene suggested a common ancestral DM mutation. A continuous gradient of repeat sizes from normal to abnormal range can explain this phenomenon.
authors.affiliation: Department of Geriatric Medicine, Ehime University School of Medicine, Onsengun, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Yamagata
authors.forename: M
authors.initials: M
authors.lastname: Kinoshita
authors.forename: T
authors.initials: T
authors.lastname: Komori
authors.forename: I
authors.initials: I
authors.lastname: Kondo
authors.forename: T
authors.initials: T
authors.lastname: Miki
mesh_terms: D000328:Adult; D000368:Aged; D002675:Child, Preschool; D004247:DNA / Q000032:analysis* / Q000235:genetics; D005190:Family; D005260:Female; D005838:Genotype; D006239:Haplotypes; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D009223:Myotonic Dystrophy / Q000235:genetics* / Q000473:pathology; D010375:Pedigree; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D017422:Sequence Analysis, DNA; D019680:Trinucleotide Repeat Expansion
chemical_list: D004247:DNA