Defining The Nine Types Of Muscular Dystrophy

By:    Published: November 15, 2011

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Muscular dystrophy is a blanket term that refers to a group of inherited disorders associated with muscle weakness and/or the loss of muscle tissue. At one time, there wasn’t much information on muscular dystrophy. However, over the past few decades, researchers finally discovered that genetic mutations were responsible for all nine types of muscular dystrophy. Below is an overview of the nine different types of muscular dystrophy.

1. Duchenne Muscular Dystrophy (DMD)

DMD is one of the more severe forms of the disease as most people with DMD are not expected to live past their 30s. DMD is caused by a lack of the protein dystrophin, and without it, the muscle cells cannot stay intact. This form of muscular dystrophy is characterized by muscle weakness, enlarged calves, and muscle degeneration in the shoulders, hips, thighs and pelvic region. Symptoms are usually developed in childhood and will get progressively worse, eventually affecting all muscles, including the heart and the muscles needed to breathe. DMD is most common in males and is a recessive, x-linked disease, meaning it is inherited through maternal genes. Women who are carriers of the disease probably won’t show any symptoms or signs of it.

2. Becker Muscular Dystrophy (BMD)

BMD is a less severe form of Duchenne Muscular Dystrophy. It too is inherited through maternal genes and is most commonly displayed in males. The symptoms of BMD are generally similar to those of DMD, but BMD progresses at a much slower rate and those affected by this disease are expected to live up to mid to late-adulthood.

3. Emery-Dreifuss Muscular Dystrophy (EDMD)

EDMD is usually evident by the time a person is 10 years old. It’s caused by a mutation in the genes that produce the proteins lamin A, lamin C or emerin, which are produced in the membranes of each muscle cell. Symptoms of this disease include muscle weakness, stiffness of the joints and degeneration of the shoulders, upper arms and calves. Fainting may also occur due to cardiac complications. This form of muscular dystrophy also progresses slowly, but a Pacemaker may be needed in the future if the cardiac complications worsen.

4. Limb-Girdle Muscular Dystrophy (LGMD)

LGMD, like EDMD, can be inherited through either or both parents. But unlike EDMD, the genetic mutation that causes this disease can affect one of at least 15 different genes that control proteins needed for muscle function. LGMD is characterized by muscle weakness and degeneration of the hips and shoulders. Symptoms are developed in childhood or adulthood and progress slowly, sometimes resulting in cardiac complications.

5. Facioscapulohumeral Muscular Dystrophy (FSH or FSHD)

FSH or FSHD is also known as Landouzy-Dejerine. According to the Muscular Dystrophy Association, FSH is caused by a missing piece of DNA on chromosome 4. Symptoms include muscle weakness and degeneration around the eyes, mouth, shoulders, upper arms, lower legs and eventually the abs and hip muscles. The progression of this disease alternates between slow and fast. This disease is usually inherited through either parent, but may appear without any family history of the disease.

6. Myotonic Muscular Dystrophy (MMD)

MMD is also known as Steinert Disease or dystrophia myotonica (DM). This form of muscular dystrophy is caused by a section of DNA that repeats itself on either chromosome 3 or chromosome 19. If this disease is evident at birth, it’s congenital, which is the more severe form. Otherwise, it may appear during the teenage years or adulthood. General symptoms include muscle weakness and degeneration in the face, arms, hands and neck. Delayed relaxing after contracting a muscle may also occur. Some people might also experience problems seeing or breathing, or have heart or gastrointestinal problems. MMD does progress very slowly, usually over the course of 50 or 60 years, and can be inherited through either parent.

7. Oculopharyngeal Muscular Dystrophy (OPMD)

OPMD may be inherited through either or both parents and doesn’t usually develop until the person is in his or her 40s or 50s. OPMD is caused by a malfunctioning gene that controls the protein, PABN1. This faulty gene causes the body to overproduce a chemical substance that clumps in the muscle cells. Symptoms of OPMD include muscle weakness, particularly of the eyelids and throat. As the disease progresses, it causes weakness of the limbs and facial muscles. Difficulty swallowing and keeping the eyelids open are common. This form of muscular dystrophy tends to progress slowly.

8. Distal Muscular Dystrophy (DD)

DD is one of the less severe forms of the disease as it is not life-threatening. It is caused by a genetic mutation in one of at least eight different genes of proteins that control muscle function. DD is slow-progressing and is characterized by muscle weakness and degeneration of the hands, forearms and legs. Symptoms may show in either childhood or adulthood. DD may be inherited from either or both parents.

9. Congenital Muscular Dystrophy (CMD)

CMD is evident at birth or shortly thereafter. It is causes by a genetic mutation that affects the proteins that control the eyes and/or brain. The genetic mutation may be spontaneous, or it may be inherited from both parents. Symptoms of CMD depend on the severity of the disease and can include muscle weakness, joint stiffness or looseness, curvature of the spine, seizures, eye defects, difficulty breathing, learning disabilities or mental retardation. If the disease is more severe, it can progress rapidly and even shorten the person’s life span.

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