Currently, the average life expectancy for people with Duchenne is 27 years , and it may improve in time, as treatment progresses. A person with muscular dystrophy is likely to need lifelong assistance.
A great deal is known about the mechanisms of muscular dystrophy, both muscular and genetic, and although a full cure may be some distance away, there are avenues of research that draw ever closer to one. Because the specific gene involved in muscular dystrophy has been found, a replacement gene that could create the missing dystrophin protein is a sensible consideration.
There are complicated problems with this approach, including the potential of the immune system to repel a new protein and the large size of the dystrophin gene needing to be replaced. There are also difficulties in targeting viral vectors directly to the skeletal muscle.
Another approach targets utrophin production. Utrophin is a protein similar to dystrophin that is not affected by muscular dystrophy. If utrophin production could be upregulated, the disease might be halted or slowed. If the dystrophin gene is being read by protein synthesis machinery and it reaches a mutation, it stops and does not complete the protein.
Drugs are being trialed that cause the protein-making equipment to skip the mutated content and still continue to create dystrophin. Rather than target the genes behind muscular dystrophy, some researchers are attempting to slow the inevitable muscle wasting. Muscles, in standard circumstances, can repair themselves. Research into controlling or increasing these repairs could show some benefits for people with muscular dystrophy. Researchers are looking at the possibility of inserting muscle stem cells capable of producing the lacking dystrophin protein.
Current projects are looking at the most useful type of cells to use and ways in which they could be delivered to skeletal muscle. During the early stages of muscular dystrophy, myoblasts also called satellite cells repair and replace faulty muscle fibers. Heart, lungs, throat, stomach, intestines, and spine. About 8 in , people of all ages are affected. Usually between 10—30 years of age, but ranges from birth to 70 years old. Which parts of the body show weakness first?
Face, neck, arms, hands, hips, and lower legs. Heart, lungs, stomach, intestines, brain, eyes, and hormone-producing organs. Learn how myotonic dystrophy is inherited external icon.
Who is more likely to be affected: males or females? Males and females equally. Childhood or adulthood, depending on the type of LGMD. Heart, spine, hips, calves, and trunk. 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. DMD was first described by the French neurologist Guillaume Benjamin Amand Duchenne in the s, but until the s, little was known about the cause of any kind of muscular dystrophy.
In , the protein associated with this gene was identified and named dystrophin. Lack of the dystrophin protein in muscle cells causes them to be fragile and easily damaged. DMD has an X-linked recessive inheritance pattern and is passed on by the mother, who is referred to as a carrier. DMD carriers are females who have a normal dystrophin gene on one X chromosome and an abnormal dystrophin gene on the other X chromosome.
Most carriers of DMD do not themselves have signs and symptoms of the disease, but a minority do. Symptoms can range from mild skeletal muscle weakness or cardiac involvement to severe weakness or cardiac effects and can begin in childhood or adulthood.
Until relatively recently, boys with DMD usually did not survive much beyond their teen years. Thanks to advances in cardiac and respiratory care, life expectancy is increasing and many young adults with DMD attend college, have careers, get married, and have children.
Survival into the early 30s is becoming more common than before. MDA-supported researchers are actively pursuing several exciting strategies in DMD, such as gene therapy , exon skipping , stop codon read-through and gene repair. Males who inherit the mutation get the disease because they have no second dystrophin gene to make up for the faulty one. Early in the embryonic development of a female, either the X chromosome from the mother maternal X or the one from the father paternal X is inactivated in each cell.
Chromosomes become inactivated at random. In each cell, there is a 50 percent chance that either the maternal or paternal X chromosome will be inactivated, with the other left active. Usually, girls do not experience the full effects of DMD the way boys do, although they still have symptoms of muscle weakness.
A minority of females with the mutation, called manifesting carriers , have some signs and symptoms of DMD. For these women, the dystrophin deficiency may result in weaker muscles in the back, legs, and arms that fatigue easily. Manifesting carriers may have heart problems, which can show up as shortness of breath or an inability to do moderate exercise. The heart problems, if untreated, can be quite serious, even life-threatening. In very rare instances, a girl may lack a second X chromosome entirely, or her second X may have sustained serious damage.
In these cases, she makes little or no dystrophin depending on the type of dystrophin mutation , and she develops a dystrophinopathy just as a boy would. A female relative of a boy with DMD can get a full range of diagnostic tests to determine her carrier status.
If she is found to be a DMD carrier, regular strength evaluations and close cardiac monitoring can help her manage any symptoms that may arise.
For more on DMD in females, see Debatable Destinies: Duchenne muscular dystrophy carriers carry on, despite uncertainty.
0コメント