The molecular basis of muscular dystrophy (肌营养不良),Wenya Hou Xue Jing Yitang Wang Jiezhong Zhang,OUTLINE,INTRODUCTION Duchenne muscular dystrophy (DMD) Dysfelin Therapeutic Approaches and perspective,a quarter of a million kids and adults are living with the disease, so chances are you may know someone who has it.,What is Muscular Dystrophy?,The muscular dystrophies (MD) are a group of more than 30 genetic diseases characterized by progressive weakness and degeneration of the skeletal muscles that control movement. Some forms of MD are seen in infancy or childhood, while others may not appear until middle age or later. Muscular dystrophies in general are a group of genetic, degenerative diseases primarily affecting voluntary muscles.,Healthy muscle tissue (left). Muscular dystrophy (right).,HOW TO RECOGNIZE IF MUSCLE WEAKNESS IS CAUSED BY MUSCULAR DYSTROPHY,Mostly affects boys (rarely girls). Often brothers or male relatives have same problem. First signs appear around ages 3 to 5: the child may seem awkward or clumsy, or he begins to walk tiptoe because he cannot put his feet flat. Runs strangely. Falls often. Problem gets steadily worse over the next several years.,HOW TO RECOGNIZE IF MUSCLE WEAKNESS IS CAUSED BY MUSCULAR DYSTROPHY,Muscle weakness first affects feet, fronts of thighs, hips, belly, shoulders, and elbows. Later, it affects hands, face, and neck muscles. Most children become unable to walk by age 10. May develop a severe curve of the spine. Heart and breathing muscles also get weak. Child usually dies before age 20 from heart failure.,There are probably nine types of muscular dystrophy.,Duchenne muscular dystrophy (DMD) Becker muscular dystrophy (BMD) Emery-Dreifuss muscular dystrophy (EDMD) Limb-girdle muscular dystrophy (LGMD) Facioscapulohumeral muscular dystrophy (FSHD) Myotonic (pronounced: my-uh-tah-nick) dystrophy (MMD) Oculopharyngeal Muscular Dystrophy (OPMD) Distal Muscular Dystrophy (DD) Congenital muscular dystrophy (CMD),Duchenne muscular dystrophy (DMD),Definition - One of nine types of muscular dystrophy, a group of genetic, degenerative diseases primarily affecting voluntary muscles. Cause - An absence of dystrophin, a protein that helps keep muscle cells intact.,DMD,Onset - Early childhood - about 2 to 6 years. Symptoms - Generalized weakness and muscle wasting first affecting the musclesof the hips, pelvic area, thighs and shoulders. Calves are often enlarged. Progression - DMD eventually affects all voluntary muscles, and the heart and breathing muscles. Inheritance - X-linked recessive. DMD primarily affects boys, who inherit the disease through their mothers. Women can be carriers of DMD but usually exhibit no symptoms.,Becker muscular dystrophy (BMD),is similar to DMD but often much less severe. There can be significant heart involvement. Progression - Disease progresses slowly and with variability. Most with BMD survive well into mid- to late adulthood.,Emery-Dreifuss muscular dystrophy (EDMD),.Cause - Mutations in the genes that produce emerin, lamin A or lamin C, proteins in the membrane that surrounds the nucleus of each muscle cell. Onset - Usually by 10 years of age. Symptoms - Weakness and wasting of shoulder, upper arm and calf muscles; joint stiffening; fainting (because of cardiac abnormalities). Progression - Disease usually progresses slowly. Cardiac complications are common and sometimes require a pacemaker. Inheritance -Can be X-linked recessive, primarily affecting males, who inherit the disease through their mothers. Another type is autosomal dominant, meaning it can be inherited through either parent; an autosomal recessive type occurs when a faulty gene is inherited from each parent.,Limb-girdle muscular dystrophy (LGMD),Definition - One of nine types of muscular dystrophy, a group of genetic, degenerative diseases primarily affecting voluntary muscles. Cause - A mutation in any of at least 15 different genes that affect proteins necessary for muscle function. Onset -Childhood to adulthood. Symptoms - Weakness and wasting first affecting the muscles around the shoulders and hips (limb girdles). Progression - Usually progresses slowly, with cardiopulmonary complications sometimes occurring in later stages of the disease. Inheritance - Some types are autosomal dominant, meaning LGMD is inherited from one parent. Other types are autosomal recessive and occur when a faulty gene is inherited from each parent.,Facioscapulohumeral muscular dystrophy (FSHD),Definition - One of nine types of muscular dystrophy, a group of genetic, degenerative diseases primarily affecting voluntary muscles. Cause - A missing piece of DNA on chromosome 4. Onset - Usually by age 20. Symptoms - Weakness and wasting of the muscles around the eyes and mouth, and of the shoulders, upper arms and lower legs initially, with later weakness of abdominal muscles and sometimes hip muscles. Progression - Progresses slowly with some periods of rapid deterioration. Disease may span many decad,