Emery Dreifuss Muscular Dystrophy Gene Article Questions
1. Describe in your own words what lamin proteins are, what Emery-Dreifuss muscular dystrophy is, and how the two are related. (Note, these are described in PlayPosit Lecture 7 as well as in the article)
2. Describe in your own words how Jill Viles and Priscilla Lopes-Schliep could have mutations in the same gene, but different/opposite phenotypic traits as a result of those mutations.
3. What is a “multifactorial disease”? What has genetic research in recent decades shown us about the “one gene = one disease” paradigm for understanding the etiology (cause) of genetic diseases?
4. It is difficult to secure funding for research and treatment/drug development for rare genetic diseases (described here: https://centerforhealthjournalism.org/fellowships/projects/look-how-rare-disease-research-getting-funded (Links to an external site.) ). What are your thoughts about this, and what are some potential solutions? How should society deal with this issue?
Emery–Dreifuss muscular dystrophy (EDMD) is a type of muscular dystrophy, a group of heritable diseases that cause progressive impairment of muscles. EDMD affects muscles used for movement (skeletal muscles), causing atrophy, weakness and contractures. It almost always affects the heart, causing abnormal rhythms, heart failure, or sudden cardiac death.It is rare, affecting 0.39 per 100,000 (1 per 250,000) people. It is named after Alan Eglin H. Emery and Fritz E. Dreifuss.
Signs and symptoms
Humeral muscle atrophy and elbow contracture in person with EDMD
The classic triad of EDMD consists of early contractures, muscle weakness, and heart involvement, typically manifesting in adolescence.
Contractures often manifest before weakness, and they can be more disabling. They tend to fix the elbow into flexion and ankle into plantarflexion via Achilles tendon shortening. The spine is also affected, with limited neck flexion initially, and eventually the entire spine can become fixed into extension, referred to as a rigid spine. Elbow and neck contractures seldom occur in other diseases. Eventually, orthopedics (walker, cane) may be needed.
The weakness is slowly progressive and preferentially involves the muscles that overlie the humerus bone (biceps and triceps muscles) and those situated on the outside of the lower leg (peroneal). Later, the muscles that position the scapula can be weakened, completing a pattern that is termed ‘scapulohumeroperoneal.' Weakness of the scapular fixators can cause a winged scapula, which can impair the ability to lift the arms over the head and can be painful. Weakness of the peroneal muscles can result in toe walking, which can present in the first decade of life. Facial, hand, and thigh muscles can be affected, although less often. Calf hypertrophy can occur.
Involvement of the heart occurs in almost all cases, presenting as syncope in second or third decades, or as sudden cardiac death. A multitude of cardiac arrhythmias can result, requiring a pacemaker often by age 30 years. Reported arrhythmias include bradycardia, atrial fibrillation/flutter, atrioventricular conduction defect, and atrial paralysis. Later in the disease, cardiomyopathy can occur. Sometimes, cardiac involvement is the predominant manifestation of EDMD, with minimal involvement of the skeletal muscles.