Abstract
Dystrophinopathy is a group of inherited phenotypes arising from pathogenic variants in DMD. We evaluated the clinical and genetic characteristics of Korean patients with genetically confirmed dystrophinopathy. We retrospectively reviewed medical records (January 2004-September 2020) from the myopathy database maintained at the study hospital and found 227 patients from 218 unrelated families with dystrophinopathy. Clinical phenotypes included 120 (53%) Duchenne muscular dystrophy (DMD) cases, 20 (9%) intermediate phenotype muscular dystrophy (IMD) cases, 65 (29%) Becker muscular dystrophy (BMD) cases, 18 (8%) undetermined phenotypes, and 4 (2%) symptomatic carriers. The median ages at symptom onset and diagnosis were 5.0 years (interquartile range [IQR]: 3.8-8.0) and 12.0 years (IQR: 7.0-21.0), respectively. Total manual muscle test (MMT) scores decreased annually in patients with DMD, IMD, and BMD. Overall, when age increased by 1 year, total MMT scores decreased on average by -1.978, -1.681, and -1.303 in patients with DMD (p<0.001), IMD (p<0.001), and BMD (p<0.001), respectively. Exonic deletion and duplication were reported in 147 (67%) and 31 (14%) of the 218 unrelated probands, respectively. A total of 37 different small sequence variants were found in 40 (18%) of the 218 probands. The reading frame rule was applicable to 142 (94%) of the 151 probands. The present results highlight the long-term natural history and genetic spectrum of dystrophinopathy in a large-scale Korean cohort.
Highlights
Dystrophinopathy is a group of inherited phenotypes arising from pathogenic variants in Duchenne muscular dystrophy (DMD) [1, 2]
Five subgroups were defined, including DMD, Becker muscular dystrophy (BMD), intermediate phenotype muscular dystrophy (IMD), undetermined phenotype (UD) and symptomatic carriers
Overall, when age increased by 1 year, total manual muscle test (MMT) scores decreased on average by -1.978, -1.681, and -1.303 in patients with DMD (p
Summary
Dystrophinopathy is a group of inherited phenotypes arising from pathogenic variants in DMD [1, 2]. University College of Medicine for 2020 (3-20200127). The funder provided support in the form of salaries for authors [S.A.L., W.A.C., S.W.K., G.P, S. L. Y.C.C. and H.J.P], but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section
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