LEARN ABOUT DUCHENNE MUSCULAR DYSTROPHY
DUCHENNE MUSCULAR DYSTROPHY
Duchenne muscular dystrophy is the commonest serious muscle disorder in children and occurs in approximately one in every five thousand boys born. Although Duchenne muscular dystrophy is an inherited disease, at present from the initial stages of fetal development, there is no physical indication at birth that the baby is anything less than normal.
It is rare for any delay in development to be noticed in the first year of life . Problems are usually not evident until 18 months to 4 years of age. On average a diagnosis is not made until the child is five, Although with increasing awareness of the problem, Some boys are diagnosed earlier . At least half of affected boys do not walk until 18 months of age or later.
In retrospect, almost all parents have noted that their child never walked or ran normally. Over the first few years of life these children have difficulty climbing and getting up from the floor. Parents often comment that their child falls frequently. Walking up on the toes is common The boys are not able to keep up with their friends in physical activities at kindergarten or school and they are often regarded as clumsy or lazy. Some parents notice that their son has large calf muscles. This enlargement is due mainly to an increase in fatty tissue in the muscle. This enlargement is a sign of muscle disease rather than a indication of good strength.
There are some boys with Duchenne muscular dystrophy who have problems with delay in mental or language development.
Duchenne Muscular Dystrophy is a rare inherited disorder characterized by progressive muscle weakness. Early symptoms usually begin between the ages of 2 to 5 years.Muscle wasting is initially limited to the shoulder and pelvic areas. Infiltration of fat and connective tissue into the muscles may produce an enlargement of the calf muscles in the legs.
Within several years Duchenne Muscular Dystrophy affects the muscles of the upper trunk and arms. Eventually all the major muscles are affected. The early symptoms of Duchenne Muscular Dystrophy may include falling, a waddling walk and awkwardness. Generally these earliest signs are attributed to clumsiness. By the age 3 to 5 years, generalized muscle weakness becomes more obvious. Parents may be falsely encouraged by a seeming improvement between the ages of 3 and 7, but this may be due to natural growth and development. Weakness progresses rapidly after age 8 or 9, resulting in the inability to walk or stand alone. Leg braces may make walking possible for a year or two, but by early adolescence walking becomes impossible.
In the late stages of Duchenne Muscular Dystrophy there is a noticeable shortening of muscles and the loss of muscle tissue. This may result in the inability to move the major joints of the body . There may also be a noticeable increase in the curvature of the spine . Lung capacity may decrease, resulting in an increased susceptibility to respiratory infections.
CAUSES OF DUCHENNE MUSCULAR DYSTROPHY
Scientists discovered exactly which piece of genetic material is missing in Duchenne muscular dystrophy patients . They were then able to work out which protein in the body this genetic material makes. The protein is called dystrophin. Boys who have Duchenne muscular dystrophy do not have the genetic material that gives the message to the body to make dystrophin. Without dystrophin Duchenne muscular dystrophy occurs.
Dystrophin is a large protein which is found on the inner side of the membrane surrounding each muscle fibre. It seems to be important in maintaining the shape and structure of the muscle fibre If dystrophin is missing the muscle fibre breaks down and is unable to work properly. Normally, muscle fibres are able to be replaced by regeneration. During the first few years , muscle fibres that break down in boys with Duchenne muscular dystrophy are being replaced. But the body has only a limit to continue replacing muscle fibres . Eventually the rate of regeneration cannot keep up with the rate of degeneration. As a result, there is a reduction in the number of good muscle fibres and the whole muscle becomes weaker.
Duchenne Muscular Dystrophy is a rare neuromuscular disorder that is inherited as an X-linked recessive trait. The gene that is responsible for this disorder has been identified on the short arm of the X chromosome. Symptoms develop due to a lack of the protein dystrophin in the muscles. Human traits, including the classic genetic diseases, are the product of the interaction of two genes, one received from the father and one from the mother. X-linked recessive disorders are conditions that are coded on the X chromosome. Females have two X chromosomes, but males have one X chromosome and one Y chromosome.Therefore, in females, disease traits on the X chromosome can be masked by the normal gene on the other X chromosome. Since males only have one X chromosome, if they inherit a gene for a disease present on the X, it will be expressed. Men with X-linked disorders transmit the gene to all their daughters, who are carriers, but never to their sons. Women who are carriers of an X-linked disorder have a fifty percent risk of transmitting the carrier condition to their daughters, and a fifty percent risk of transmitting the disease to their sons.
Approximately 30 percent of patients with Duchenne Muscular Dystrophy have no family history of the disorder. This can mean that the genetic mutation is new in those families . The disorder is diagnosed by finding a deficiency of dystrophin in the muscles. Only males are affected, with rare exceptions. Female relatives of affected males may be carriers. The mothers of affected males, in families with more than one affected male, are carriers. The mothers of affected males with no affected relatives are not always carriers, because their sons may have been affected by new mutations. The son of a carrier has a 50% probability of being affected. The daughter of a carrier has a 50% probability of being a carrier. The sons of an affected male are all unaffected; his daughters are all carriers.
TEST TO DETERMINE DUCHENNE
Creatine kinase (CK) test CK is an enzyme (protein) that is important for energy production within muscle fibres. If a muscle fibre is damaged by a disease process such as muscular dystrophy, some of the CK leaks out into the blood. Normally there is only a small amount in the blood but in Duchenne muscular dystrophy there may be 10 to 100 times the normal amount. There are very few other disease processes which cause such a high level of CK in the blood. Electromyography (EMG). When muscles contract (shorten) there is electricity flowing through the muscle tissue.
An abnormal muscle has an abnormal pattern of electricity that can be recognized and recorded using special equipment.An EMG test involves putting a small needle through the skin into a muscle and recording the pattern of electricity in the muscle when it is contracting. Muscle biopsy Muscle from patients with muscular dystrophy looks different from normal muscle when it is seen under a microscope. The small piece of muscle that is removed during the biopsy is cut into very thin slices, stained with a series of special dyes to show the different types of muscle fibres, and studied by a pathologist. A DNA blood test to analysis the X chromosome (PCR--polymerase chain reaction )
Duchenne Muscular Dystrophy affects only males, with rare exceptions. Unless a boy with DMD is known to be at risk because of his family history, he is unlikely to be diagnosed before the age of 2 or 3 years. Most boys with DMD walk alone at a later age than average. Then the parents are likely to be worried about something unusual in the way he walks, about frequent falling or about difficulty rising from the ground or difficulty going up steps. How is the diagnosis for DMD made? Usually , by the time a doctor is consulted there is an effect on posture and gait , in the way the affected boy stands, walks, runs, especially up hills or steps. The doctor is likely to observe that the calf muscles and sometimes other muscles look very well developed or excessively large. Other muscles will be poorly developed. There is usually a typical style of walking which can be recognized and which is something described as waddling. Whether standing still or walking, the affected boy usually has an exaggeration of the forward curve of the lower part of the back. The medical term for this is lordosis, non-medical people sometimes call it sway-back.
A later development is a tendency to stand and walk on the forward part of the foot with the heels off the ground. Testing individual muscles or muscle groups reveals a pattern of weakness which is typical of DMD. Can DMD be diagnosed before these features are obvious? If parents have brought their son to a doctor at a very early stage of the disease, it may be difficult or impossible to detect anything definitely wrong on observing him. Doctors are therefore encouraged to test for DMD, with a blood test, whether they strongly suspect the diagnosis or regard it as just a possibility.
Something very important that Parent's with children with Duchenne Muscular Dystrophy should know is that these children can not use the normal anastasia.
The normal anastasia will make there air way swell up and will not allow them to breath.
Let all your Doctor's and Dentist know the childs condition so they can mark this in there charts and records.
For more information on Duchenne's Muscular Dystrophy please contact
Muscular Dystrophy Association
USA National Headquarters
3300 E. Sunrise Drive
Tucson, AZ 85718
Other Muscular Dystrophy websites: