How can muscular dystrophy be inherited

Until the s, little was known about the cause of any of the forms of muscular dystrophy. In , MDA-supported researchers identified a gene on the X chromosome that, when flawed mutated , causes Duchenne, Becker , and an intermediate form of muscular dystrophies.

Genes contain codes, or recipes, for proteins, which are important biological components in all forms of life. In , the protein associated with the DMD gene was identified and named dystrophin. The dystrophin gene is the largest gene yet identified in humans and is located in the short arm of the X chromosome, in the Xp The majority of mutations of the dystrophin gene are deletions of one or more parts of it. Individuals with BMD genetic mutations make dystrophin that is partially functional, which protects their muscles from degenerating as badly or as quickly as in DMD.

The dystrophin protein transfers the force of muscle contraction from the inside of the muscle cell outward to the cell membrane. Because it connects the center of the muscle cell to the edge of the cell, the dystrophin protein is extremely long.

One end is specialized for linking to the muscle cell interior and the other end is specialized for linking to a variety of proteins at the cell membrane. The long middle section, called the rod domain, is taken up by a series of repeating units called spectrin repeats. The repeated spectrin units in the middle of the protein play an important role in linking the two ends, but studies have shown that the exact number of these units is not critical for the function of the protein as a whole.

Many cases of DMD are caused by mutations in the part of the gene that encodes this middle section. Production of the entire protein stops when the mutation is encountered. The absence of dystrophin sets in motion a cascade of harmful effects. In addition to its force-transfer role, dystrophin provides the scaffold for holding numerous molecules in place near the cell membrane. Loss of dystrophin displaces these molecules, with consequent disruptions in their functions.

Lack of dystrophin causes muscle damage and progressive weakness, beginning in early childhood. Every boy inherits an X chromosome from his mother and a Y chromosome from his father, which is what makes him male.

Learn how limb-girdle muscular dystrophy is inherited external icon. Face, shoulders, and upper arms. Learn how facioscapulohumeral dystrophy is inherited external icon. Neck, upper arms, upper legs, and lungs. Learn how congenital muscular dystrophy is inherited external icon. Feet, hands, lower legs and lower arms. Learn how distal muscular dystrophy is inherited external icon. Shoulders, upper legs, and hips. Learn how oculopharyngeal muscular dystrophy is inherited external icon.

Learn how Emery-Dreifuss muscular dystrophy is inherited external icon. Skip directly to site content Skip directly to page options Skip directly to A-Z link. Muscular Dystrophy. Section Navigation. Facebook Twitter LinkedIn Syndicate. What is Muscular Dystrophy? Minus Related Pages. About 14 in , males 5 — 24 years of age Who is more likely to be affected: males or females?

Males When does muscle weakness typically begin? Upper legs and upper arms What other parts of the body can be affected? Myotonic DM. About 8 in , people of all ages are affected Who is more likely to be affected: males or females? Males and females equally When does muscle weakness typically begin? Face, neck, arms, hands, hips, and lower legs What other parts of the body can be affected? Heart, lungs, stomach, intestines, brain, eyes, and hormone-producing organs Learn how myotonic dystrophy is inherited external icon.

About 2 in , people of all ages Who is more likely to be affected: males or females? Upper arms, upper legs What other parts of the body can be affected? Heart, spine, hips, calves, and trunk Learn how limb-girdle muscular dystrophy is inherited external icon. Facioscapulohumeral FSHD. About 4 in , people of all ages Who is more likely to be affected: males or females? Young adulthood Which parts of the body show weakness first? Face, shoulders, and upper arms What other parts of the body can be affected?

Eyes, ears, and lower legs Learn how facioscapulohumeral dystrophy is inherited external icon. Congenital CMD. Muscular Dystrophy News is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment.

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