BASIC FACTS ABOUT MUSCULAR DYSTROPHY

What is Muscular Dystrophy (MS)?

Muscular dystrophy is a cluster of hereditary diseases characterized by progressive degeneration and weakening of skeletal muscles. There are 12 types of human muscular dystrophies, including:

Duchenne
Myotonic
Becker
Facioscapulohumeral
Limb girdle
and other less common forms.

The first recognized case was reported in 1830, but this disease is likely to have been a present in human development much before that. This is an inheriting disease and there are different types of muscular dystrophy inheriting differently. Therefore it can be called as sex linked inheritance because this disease causing factor is carried on the x chromosome. In males the presence of this disease is 50% as compared to female, because in women there are 2 x chromosomes are present that is both of these chromosomes can be altered. If in women who only have 1 altered x chromosome are said to be carriers, and often suffer from much milder symptoms.

Muscular dystrophies are characterized by progressive skeletal muscle weakness, defects in muscle proteins, and the death of muscle cells and tissue. Mainly nine diseases including Duchenne, Becker, limb girdle, congenital, facioscapulohumeral, myotonic, oculopharyngeal, distal, and Emery-Dreifuss are always classified as muscular dystrophy, but there are more than 100 diseases in total with similarities to muscular dystrophy. Most types of MD are multi-system disorders with manifestations in body systems including the heart, gastrointestinal and nervous systems, endocrine glands, skin, eyes and other organs.

Symptoms of Muscular Dystrophy

There are a number of symptoms associated with muscular dystrophy. The principal symptoms include: progressive muscle wasting, weakness, and loss of function, in Duchenne's MD, delayed development of basic muscle skills and coordination in children. Common signs include poor balance with frequent falls, walking difficulty with waddling gait and calf pain, and limited range of movement, obesity, joint contractures, cataracts, frontal baldness, drooping eyelids, gonadal atrophy, and mental impairment (with myotonic dystrophy).

The other mild symptoms are poor balance, frequent falls, walking difficulty, waddling gait, calf pain, limited range of movement, muscle contractures, respiratory difficulty, drooping eyelids (ptosis), gonadal atrophy, scoliosis (curvature of the spine), inability to walk etc. Few or none of these symptoms may be present before diagnosis. Some types of Muscular Dystrophy can affect the heart, causing cardiomyopathy or arrhythmias.

Kinds of Muscular Dystrophy

The muscular dystrophy is divided into several types based on their effects and progressive symptoms. Several of the major types of muscular dystrophy are following.

Duchenne muscular dystrophy (DMD): This is one of the more common kind of MD, and it is caused by a mis-function in the procedure of producing dystrophin (a type of protein). If the process is completed correctly, that protein will make the muscles solid and stay in shape. Thus, without the protein, a person will become very vulnerable as the muscles break down. Unfortunately, people suffering from DMD often pass away before they fully grow up.

Facioscapulohumeral Muscular Dystrophy (FMD): the main difference between FMD and DMD is that FMD symptoms often come out when a person is in his/her adolescent years. Bit By Bit it makes the legs, arms, chest and face muscles weaker and weaker; nevertheless the symptoms could also deviate from person to person.

Myotonic Muscular Dystrophy (MMD): a person with MMD often finds its symptoms when they have turned adult. This form of MD causes difficulty for the muscles to loosen, therefore sometimes make the muscles shrink over time. It can also result in heart troubles if the patient doesn't have medical care soon enough.

Becker muscular dystrophy (BMD): like DMD, it affects boys. The disease is very much related to DMD, but its symptoms may begin later and can be less severe. With BMD, symptoms like muscle breakdown and weakness sometimes don't begin until age 10 or even in adulthood. People with BMD can also have breathing, heart, bone, muscle, and joint problems. Many people with BMD can live long, active lives without using a wheelchair. How long a person with BMD can live varies depending on the severity of any breathing and heart problems.

Congenital muscular dystrophy (CMD) is the term for all types of MD that show signs in babies and young children, although the MD isn't always diagnosed right away. Like other forms of MD, CMD involves muscle weakness and poor muscle tone. Occurring in both girls and boys, it can have different symptoms. It varies in how severely it affects people and how quickly or slowly it worsens. In rare cases, CMD can cause learning disabilities or mental retardation.

Limb-girdle muscular dystrophy (LGMD) affects boys and girls equally, weakening muscles in the shoulders and upper arms and around the hips and thighs. LGMD can begin as early as childhood or as late as mid-adulthood, and it often develops slowly. Over time, a wheelchair might be required to get around. There are many diverse types of LGMD, each with its own specific features.

Symptoms and prognosis vary, depending on the type of MD. The disease may affect some or all muscles, may develop during childhood or adulthood, may progress very gradually or rapidly, and may or may not be severely disabling.

Boys with Duchenne's MD are usually in a wheelchair by the age of 12 and rarely live past age 20; on the other hand, people with facioscapulohumeral MD often have a normal life span and usually remain able to walk, since the leg muscles are only mildly affected. Also, in some types of MD, the rate of progression and the extent of disability varies substantially from patient to patient.

Most forms of MD affect the heart muscle and this result in cardiomyopathy. All forms of MD result from some type of genetic defect. In the majority of cases, the defect is inherited and affects various relatives throughout a family. In a few cases, the disorder may result from a genetic mutation.

Treatment of Muscular Dystrophy

There is no specific treatment to cure or stop MD. Physical therapy, exercise, orthopedic appliances (such as braces and wheelchairs), or corrective orthopedic surgery may help to preserve muscle function and prevent joint contractures as much as possible and improve quality of life. Steroids have been used to slow disease progression, but do not affect the final outcome. Identification of the specific genes responsible for the various types of MD has led to extensive research on gene and molecular therapy, but all such treatments are still experimental.