Introduction to Muscular Dystrophies and Related Disorders

Muscular dystrophies are a group of inherited muscle disorders in which one or more genes Genes Genes are segments of deoxyribonucleic acid (DNA) that contain the code for a specific protein that functions in one or more types of cells in the body or the code for functional ribonucleic... read more needed for normal muscle structure and function are defective, leading to muscle weakness Weakness Weakness refers to loss of muscle strength. That is, people cannot move a muscle normally despite trying as hard as they can. However, the term is often misused. Many people with normal muscle... read more of varying severity. Muscle fibers appear deteriorated (dystrophic) when viewed under a microscope. Facioscapulohumeral dystrophy Facioscapulohumeral Muscular Dystrophy Facioscapulohumeral muscular dystrophy is the most common form of muscular dystrophy. The muscles of the face and shoulder are affected. Muscular dystrophies are a group of inherited muscle... read more is the most common form of muscular dystrophy. Duchenne muscular dystrophy Duchenne Muscular Dystrophy and Becker Muscular Dystrophy Muscular dystrophies are a group of inherited muscle disorders in which one or more genes needed for normal muscle structure and function are defective, leading to muscle weakness of varying... read more and Becker muscular dystrophy Duchenne Muscular Dystrophy and Becker Muscular Dystrophy Muscular dystrophies are a group of inherited muscle disorders in which one or more genes needed for normal muscle structure and function are defective, leading to muscle weakness of varying... read more are the second most common forms. Duchenne muscular dystrophy is a more severe form. Becker muscular dystrophy is closely related to Duchenne dystrophy but starts later in a child's life and causes milder symptoms.

Other forms of muscular dystrophy include Emery-Dreifuss dystrophy Emery-Dreifuss Dystrophy Emery-Dreifuss dystrophy is a muscular dystrophy that is inherited in various ways. In addition to weakness and muscle wasting, people often have heart problems that may cause sudden death.... read more , myotonic dystrophy Myotonic Dystrophy Myotonic dystrophy is a rare muscular dystrophy. This disorder affects the ability to relax the muscles at will. Myotonia refers to delayed relaxation after muscle contraction, which can cause... read more , limb-girdle dystrophy Limb-Girdle Dystrophy Limb-girdle dystrophy encompasses a group of muscular dystrophies that can be inherited in various ways. The muscles of the shoulder or pelvis are affected. Muscular dystrophies are a group... read more , and congenital dystrophies Congenital muscular dystrophy Muscular dystrophies are a group of inherited muscle disorders in which one or more genes needed for normal muscle structure and function are defective, leading to muscle weakness of varying... read more .

Other inherited muscle disorders include congenital myopathies Congenital Myopathies Congenital myopathies are rare, inherited disorders of the muscles that cause reduced muscle tone and weakness. These disorders are present at birth or show up during infancy. There are several... read more , myotonia congenita Myotonia Congenita Myotonia congenita is an inherited disorder that causes muscle stiffness and muscle enlargement. It affects what most people think of as muscle, the type that can be contracted to move the various... read more , familial periodic paralysis Familial Periodic Paralysis Familial periodic paralysis is a rare inherited disorder that causes sudden attacks of weakness and paralysis. There are four different forms, which involve abnormalities in how electrolytes... read more , and glycogen storage diseases. Glycogen storage diseases Glycogen Storage Diseases Glycogen storage diseases are carbohydrate metabolism disorders that occur when there is a defect in the enzymes that are involved in the metabolism of glycogen, often resulting in growth abnormalities... read more are a group of rare inherited disorders in which muscles cannot metabolize sugars normally, so they build up large stores of glycogen (a starch that is formed from sugars). Mitochondrial disorders Mitochondrial Disorders Mitochondrial disorders are a group of hereditary metabolic disorders that occur when mitochondria do not function correctly in the body. Hereditary disorders occur when parents pass the defective... read more affect the muscles as well as other parts of the body.