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Muscular Dystrophies
Muscular dystrophy classifies a group of genetically inherited disorders resulting from defects in a number of genes required for normal muscle function. Muscle strength and bulk gradually decline. Muscular dystrophies are generally recognized and classifies into 9 different categories.
Duchenne Muscular Dystrophy (DMD) (also known as Pseudohypertrophic)Duchenne Muscular Dystrophy is classified with having the most severe clinical symptoms. DMD is a disease resulting from inheritance of an X-linked recessive gene, causing an absence of dystrophin, a protein that helps keep muscles in tact. DMD primarily affects boys, who inherit the disease through their mothers. Women can be carriers of DMD but usually exhibit no symptoms. The onset of DMD typically occurs between the ages of 2 to 6 years of age. Symptoms include general weakness and muscle wasting first affecting the muscles of the hips, pelvic area, thighs and shoulders. Calves are also often enlarged. Eventually, DMD afftects all voluntary muscles, and the heart and breathing muscles. Patients rarely live beyond their early 30s.
Becker Muscular Dystrophy (BMD)Becker Muscular Dystrophy, one of the nine types of muscular dystrophies, is a degenerative disease primarily affecting voluntary muscles. BMD is a disease resulting from inheritance of an X-linked recessive gene. As a result there is an insufficient production of dystrophin, a protein that helps keep muscles intact. BMD primarily affects boys and men, who inherit the disease through their mothers. Women can be carriers but usually exhibit no symptoms. Usually symptoms show at adolescence or adulthood. BMD is similar to Duchenne muscular dystrophy but often much less severe. Patients usually show generalized weakness and wasting first affecting the muscles of the hips, pelvic area, thighs and shoulders. Calves are often enlarged and there can also be significant heart involvement. The disease progresses slowly and with variability, but can affect all voluntary muscles. Most patients with BMD can survive well into mid to late adulthood.
Emery-Dreifuss Muscular Dystrophy (EDMD)Emery-Dreifuss Muscular Dystrophy (EDMD) is a degenerative disease primarily affecting voluntary muscles. EDMD can be X-linked recessive, primarily affecting males, who inherit the disease through their mothers. Another type of inheritance is autosomal dominant. This means the disease can be inherited through either the mother or the father. An autosomal recessive types occurs when a faulty gene is inherited from each parent. Mutations occur in genes that produce emerin, lamin A or lamin C, all which are proteins in the membrane that surround the nucleus of each muscle cell. Symptoms usually onset by age 10 and include weakness and wasting of shoulder, upper arm and calf muscles. EDMD patients also suffer from joint stiffening and fainting (because of cardiac abnormalities). Cardiac complications are common and sometimes require a pacemaker.
Limb-Girdle Muscular Dystrophy (LGMD)Limb-Girdle Muscular Dystrophy (LGMD) is a degenerative disease primarily affecting the voluntary muscles. LGMD can be inherited from just one parent (autosomal dominant). Other types are autosomal recessive, meaning the disease is brought on when a faulty gene is inherited from each parent. LGMD results in a mutation in any of at least 15 different genes that affect proteins necessary for muscle function. Usually symptoms are brought on anywhere from childhood to adulthood. The disease usually progresses slowly with weakness and wasting first affecting the muscles around the shoulders and hips. Cardiopulmonary complications sometimes occur in later stages of the disease.
Facioscapulohumeral Muscular Dystrophy (FSHD)Facioscapulohumeral Muscular Dystrophy (FSHD), also known as Landouzy-Dejerine, is degenerative disease primarily affecting voluntary muscles caused by a missing piece of DNA on chromosome 4. FSHD may be inherited through either the father or the mother (autosomal dominant). Although diagnosed by age 20, the disease progresses slowly with some periods of rapid deterioration and may span many decades. Weakness and wasting of the muscles around the eyes and mouth, and of the shoulders, upper arms and lower legs are common initially; however, as the disease progresses, weakness of abdominal muscles and sometimes hip muscles is common.
Myotonic Dystrophy (MMD)Myotonic Dystrophy (MMD), also known as Steinert's Disease, is a degenerative disease primarily affecting voluntary muscles, and is caused by a repeated section of DNA on either chromosome 19 or chromosome 3. MMD is autosomal dominant and may be inherited through either the father or mother. Congenital (existing at birth) myotonic dystrophy is the more severe form. The more common form may begin in teen or adult years. The progression of the disease is usually slow, sometimes spanning 50 to 60 years. Generalized weakness and muscle wasting first affecting the face, lower legs, forearms, hands and neck, with delayed relaxation of muscles after contraction is common. Other symptoms involve the gastrointestinal system, vision, heart or respiration. Learning disabilities also occur in some cases.
Oculopharyngeal Muscular Dystrophy (OPMD)Onset: Early adulthood to middle age.
Distal Muscular Dystrophy (DD)
Onset: 40 to 60 years of age.
Congenital Muscular Dystrophy (CMD)Congenital Muscular Dystrophy (CMD) is a degenerative disease primarily affecting voluntary muscles resulting from genetic mutations affecting some of the proteins necessary for muscles and sometimes for the eyes and or brain. The disease is inherited through both parents. Brought on at or near birth, CMD varies with type. Many are slowly progressive; some shorten life span. Common symptoms include generalized muscle weakness with possible joint stiffness or looseness. Depending on the type, CMD may involve spinal curvature, respiratory insufficiency, mental retardation or learning disabilities, eye defects or seizures.
