BACKGROUND: Duchenne muscular dystrophy (DMD) is the most common disease in 
children caused by mutations in the DMD gene, and DMD and Becker muscular 
dystrophy (BMD) are collectively called dystrophinopathies. Dystrophinopathies 
show a complex mutation spectrum. The importance of mutation databases, with 
clinical phenotypes and protein studies of patients, is increasingly recognized 
as a reference for genetic diagnosis and for the development of gene therapy.
METHODS: We used the data from the Japanese Registry of Muscular Dystrophy 
(Remudy) compiled during from July 2009 to March 2017, and reviewed 1497 
patients with dystrophinopathies.
RESULTS: The spectrum of identified mutations contained exon deletions (61%), 
exon duplications (13%), nonsense mutations (13%), small deletions (5%), small 
insertions (3%), splice-site mutations (4%), and missense mutations (1%). Exon 
deletions were found most frequently in the central hot spot region between 
exons 45-52 (42%), and most duplications were detected in the proximal hot spot 
region between exons 3-25 (47%). In the 371 patients harboring a small mutation, 
194 mutations were reported and 187 mutations were unreported.
CONCLUSIONS: We report the largest dystrophinopathies mutation dataset in Japan 
from a national patient registry, "Remudy". This dataset provides a useful 
reference to support the genetic diagnosis and treatment of dystrophinopathy.