Case Report: The effect of early initiation of eteplirsen treatment on the cardiac and motor disease course in an individual with Duchenne muscular dystrophy.

Duchenne muscular dystrophy (DMD) is an X-linked disorder characterized by progressive muscle weakness. Here we provide a case report for a male aged 7 years and 3 months diagnosed with DMD after detecting a deletion of exons 48-50 of the DMD gene. The child initially presented with elevated transaminases during a febrile illness at 17 months. Further evaluation revealed significantly increased creatine phosphokinase and troponin levels. He exhibited delayed gross motor milestones and developed left ventricular diastolic dysfunction. At 24 months of age, weekly intravenous eteplirsen therapy was initiated, along with enalapril to manage cardiac symptoms. Over 5 years, the patient demonstrated stable cardiac function and gradual motor improvement. Despite persistent hyperlordosis and waddling gait, his 6-minute walk test remained stable. To our knowledge, this is the first documented case of DMD reporting cardiac outcomes after eteplirsen treatment in a patient as young as 24 months of age.