Scapuloperoneal Myopathy and Cardiomyopathy with a Novel MYH7 Mutation: A Case Report

Abstract

Introduction:

Myosin heavy chain 7 (MYH7)-related myopathies have variable clinical features and onsets and are emerging as a group of muscle diseases that affect a wide range of age groups. While individuals with (MYH7)-related myopathies will present with cardiac or skeletal involvement, it is less common to see cardiac and skeletal involvement occurring in a single individual. 

Case Report:

A 66-year old right-handed woman presented to the clinic for progressive ascending weakness, weight loss, and severe dysphagia. Symptoms first arose when the patient was in her 20s when she reported lower extremity weakness. Over the years, the weakness has ascended, and today the patient is unable to raise her arms. The patient has a family history of muscle disease, but testing has not been done. Neurological examination of mental status and cranial nerve were intact. Shoulder abduction, flexion, and extension was 2/5 bilaterally. Hip flexion was 3/5, and foot dorsiflexion was 2/5 bilaterally. There was no elevation of serum creatinine, and EMG showed myopathic process. Muscle biopsy of the deltoid revealed a myopathic changes with mini cores. EKG reveals first degree AV block with anterior ischemia and echocardiogram showing features of dilated cardiomyopathy. The genetic panel revealed c.4522_c.4524del (p.Glu1508del) resulting in pathogenic mutation of MYH7 leading to scapuloperoneal myopathy.

Discussion:

This case report illustrates the variability in clinical presentation of adult-onset MYH7 myopathy. MYH7 gene-related myopathies have notable clinical variability that can lead to the missed or late diagnosis of this progressive myopathy. While our case highlights the pertinent family history and co-existing cardiac involvement that is strongly associated with MYH7 related myopathy, it also illustrates further cases of MYH7 mutations causing both cardiac and skeletal muscle disease.