Duchenne muscular dystrophy (DMD), the most common inherited muscular disease in childhood, is caused by dystrophin deficiency because of mutations in the DMD gene. Although DMD is characterized by fatal progressive muscle wasting, cardiomyopathy is the most important non-muscle symptom threatening the life of patients with DMD. The relationship between cardiac involvement and dystrophin isoforms has not been analyzed. The results of 1109 echocardiograms obtained from 181 Japanese DMD patients with confirmed mutations in the DMD gene were retrospectively analyzed. Patients showed an age-related decline in left ventricular ejection fraction. Patients were divided by patterns of dystrophin isoform deficiency into 5 groups. The cardiac dysfunction-free survival was significantly higher in the group with mutations in the Dp116 coding region than the others, whereas there were no significant differences in the other 3 groups. At age 25 years, the cardiac dysfunction-free rate was 0.6 in the Dp116 group, but only 0.1 in others. The authors conclude that cardiac dysfunction was less frequent in Dp116-deficient than other patients with DMD. Furthermore, this ic the first study to identify Dp116 transcript in human cardiac muscle. These results indicate that Dp116 is associated with cardiac involvement in DMD.
