Molecular and Clinical Characteristics of Myotonic Dystrophy Type 1 in Koreans.
10.3343/kjlm.2008.28.6.483
- Author:
So Yeon KIM
1
;
Ji Yeon KIM
;
Gyoung Pyoung KIM
;
Jung Jun SUNG
;
Kyu Sang LIM
;
Kwang Woo LEE
;
Jong Hee CHAE
;
Yoon Ho HONG
;
Moon Woo SEONG
;
Sung Sup PARK
Author Information
1. Department of Laboratory Medicine, Seoul National University College of Medicine and Seoul National University Hospital, Korea. sparkle@snu.ac.kr
- Publication Type:Original Article
- Keywords:
Myotonic dystrophy type 1;
DMPK gene;
CTG;
Trinucleotide repeat expansion;
Polymerase chain reaction;
Southern blot;
Anticipation;
Instability;
Age of onset;
Korean
- MeSH:
Blotting, Southern;
Data Interpretation, Statistical;
Female;
Genotype;
Humans;
Korea;
Male;
Myotonic Dystrophy/*diagnosis/*genetics;
Pedigree;
Phenotype;
Polymerase Chain Reaction;
Protein-Serine-Threonine Kinases/genetics;
Retrospective Studies;
Trinucleotide Repeat Expansion/genetics
- From:The Korean Journal of Laboratory Medicine
2008;28(6):483-492
- CountryRepublic of Korea
- Language:English
-
Abstract:
BACKGROUND: Myotonic dystrophy type 1 (DM1) is an autosomal-dominant muscular dystrophy caused by expansion of cytosine-thymine-guanine (CTG) trinucleotide repeats in the myotonic dystrophy protein kinase (DMPK) gene. The clinical features of DM1 are multisystemic and highly variable, and the unstable nature of CTG expansion causes wide genotypic and phenotypic presentations. The aim of this study was to characterize the molecular and clinical spectra of DM1 in Koreans. METHODS: The CTG repeats of 283 Korean individuals were tested by PCR fragment analysis and Southern blot. The following characteristics were assessed retrospectively: spectrum of CTG expansions, clinical findings, genotype-phenotype correlation, anticipation, and genetic instability. RESULTS: One-hundred twenty-four patients were confirmed as DM1 by molecular tests, and the CTG expansions ranged from 50 to 2,770 repeats (median 480 repeats). The most frequent clinical features were myotonia, muscular weakness, and family history. Patients with muscular weakness or dysfunction of the central nervous system harbored larger CTG expansions than those without each symptom (P<0.05). The age of onset was inversely correlated with the size of the CTG expansion (gamma=-0.422, P<0.001). The instability of CTG expansion representing as the maximum difference between sibships was observed from 50 to 700 repeats in nine families. Clinical anticipation and the increase in CTG repeat were significantly higher in maternally transmitted alleles (P=0.002). CONCLUSIONS: Molecular genetic tests are not only essential for diagnosis, but also helpful for suggesting the spectrum and relationship between genotype and phenotype in Korean DM1 patients.
