Emery–Dreifuss muscular dystrophy

Emery–Dreifuss muscular dystrophy is a condition that mainly affects muscles used for movement, such as skeletal muscles and also affects the cardiac muscle, it is named after Alan Eglin H. Emery and Fritz E. Dreifuss.

Signs and symptoms

Symptoms of EDMD begin in teenage years with toe-walking, rigid spine, face weakness, hand weakness and calf hypertrophy. Among other signs/symptoms of Emery–Dreifuss muscular dystrophy are:

• Muscle weakness EDMD can affect the shoulders and lower legs
• Cardiac involvement can affect an individuals heart rate (bradycardia, palpitations)
• Contractures of the muscles occurs slowly, eventually leading to the need for orthopedics (walker, cane)

Genetics

Protein LMNA

Protein EMD

Mutations in the EMD, LMNA, and several other genes cause the various types of Emery–Dreifuss muscular dystrophy. The EMD and LMNA genes provide instructions for making proteins that are components of the nuclear envelope, which surrounds the nucleus in cells. The nuclear envelope regulates the movement of molecules into and out of the nucleus, and researchers believe it may play a role in regulating the activity of certain genes.

Type	OMIM	Gene	Description
EDMD1	Online Mendelian Inheritance in Man (OMIM) 310300	EMD	This gene provides instructions for making a protein called emerin, a transmembrane protein of the inner nuclear membrane which appears to be essential for the normal function of skeletal and cardiac muscle. Most EMD mutations prevent the production of any functional emerin.
EDMD2, EDMD3	Online Mendelian Inheritance in Man (OMIM) 181350	LMNA	Emery–Dreifuss muscular dystrophy also results from mutations in the LMNA gene. This gene provides instructions for making two very similar proteins, lamin A and lamin C. Most of the LMNA mutations that cause this condition result in the production of an altered version of these proteins.
EDMD4	Online Mendelian Inheritance in Man (OMIM) 612998	SYNE1	Here one finds that muscle cells indicate loss of nuclear envelope consistency, additionally the affected individual experiences cerebellar ataxia at approximately 30 years of age.
EDMD5	Online Mendelian Inheritance in Man (OMIM) 612999	SYNE2	In SYNE2 we see a transition in said gene, that results in T89M as a result of a substitution. Via fluorescent in-situ hybridization the gene is located at chromosome 14q23
EDMD6	Online Mendelian Inheritance in Man (OMIM) 300696	FHL1	This x-linked type of EDMD is had via mutations in the FHL1 gene, where protein gels (Western blots) indicate less band expression, with mutations in exon 5–8 on the gene
EDMD7	Online Mendelian Inheritance in Man (OMIM) 614302	TMEM43	Heterozygous

Diagnosis

The diagnosis of Emery–Dreifuss muscular dystrophy can be established via single-gene testing or genomic testing, and clinically diagnosed via the following exams/methods:

• CAT scan
• Serum CK analysis
• EKG
• Echocardiogram
• Electromyogram
• Immunodetection

Classification

The types of Emery–Dreifuss muscular dystrophy are distinguished by their pattern of inheritance: X-linked, autosomal dominant, and autosomal recessive.

• Autosomal dominant Emery–Dreifuss muscular dystrophy individuals experience heart problems with weakness (and wasting) of skeletal muscles and Achilles tendon contractures.
• X-linked Emery–Dreifuss muscular dystrophy is the result of the EMD gene, with cardiac involvement.
• Autosomal recessive individuals with this type of the disorder demonstrate cardiac issues, such as arrhythmia. Individuals who acquire EDMD via the autosomal recessive route have an incidence of 1 in 300,000.

Treatment

The treatment (management) of Emery–Dreifuss muscular dystrophy can be done via several methods, however secondary complications should be considered in terms of the progression of EDMD, therefore cardiac defibrillators may be needed at some point by the affected individual. Other possible forms of management and treatment are the following:

ACE inhibitor

• Orthopaedics
• Surgery
• Monitor/treat any cardiac issues

• Medication (beta-blockers, ACE inhibitors)

• Respiratory aid
• Physical therapy

See also

• Laminopathies
• Noncompaction cardiomyopathy

External links

Classification	ICD-10: G71.0 ICD-9-CM: 359.1 OMIM: 181350 Online Mendelian Inheritance in Man (OMIM) 310300 Online Mendelian Inheritance in Man (OMIM) 616516 Online Mendelian Inheritance in Man (OMIM) 614302 MeSH: D020389 DiseasesDB: 31705 SNOMED CT: 129620000
External resources	eMedicine: neuro/513 GeneReviews: Emery–Dreifuss Muscular Dystrophy Orphanet: 261