EMERY-DREIFUSS MUSCULAR DYSTROPHY

·         XR (X-linked Recessive)/AD

·         a.k.a. Scapuloperoneal and Scapulohumeral Muscular Dystrophy

·         Genetics-

§  5 distinct forms

1.       Emerin gene (most common cause of XR EDMD)

2.       FHL1 gene (XR)

3.       Lamin A/C (most common cause of AD EDMD a.k.a. LGMD1B)

4.       Nesprin-1 & Nesprin-2 (AD)

5.       TMEM43 (AD)

·         Clinical Features-

§  Onset – middle childhood

§  Skeletal Muscle Involvement-

§  Early development of contractures (esp. elbows, ankles and neck) – may precede muscle weakness.

§  Muscle hypertrophy – absent

§  Weaknessand wasting of muscles in scapula-humero-peroneal distribution

§  Cardiomyopathy - maybe fatal (often cause of death in EDMD – Arrhythmias > heart failure )

§  Cardiac conduction defects-

§  Atrial Fibrillation

§  Atrioventricular Heart Block

§  Ventricular Fibrillation

·         Lab Features and Diagnosis-

§  Serum CK – mild elevation (2 to 10 fold)

§  EMG - nonspecific features of myopathy

§  Muscle Biopsy –

§  Non-specific myofibril necrosis

§  Endomysial proliferation

§  Immunohistochemical staining- absent emerin in myofibrils in XR EDMD

·         Treatment-

§  Supportive therapy

§  Pacemaker – to prevent arrhythmias

§  Ambulatory aids