BMX and Arrhythmia: Specifically, it has been reported that patients can present with arrhythmias, a decline in ejection fraction and dilated cardiomyopathy (DCM) similar to DMD patients.S11 Interestingly, one study reported a significantly earlier DCM onset in BMD patients with an exon 45–47 deletion (median age of 27 years) versus patients with a 45–48 or 45–49 deletion (median ages of 38 and 41 years, respectively).S12 Here we utilized echocardiography to measure heart function in aged bmx mice.