|Form of MD
||What It Is
||How It Develops
||The most common and severe form of MD among children, DMD accounts for more than 50% of all cases. DMD is caused by a deficiency of dystrophin, a protein that helps strengthen muscle fibers and protect them from injury.2
||Weakness begins in the upper legs and pelvis. People with DMD may also:
- Fall down a lot
- Have trouble rising from a lying or sitting position
- Waddle when walking
- Have difficulty running and jumping
- Have calf muscles that appear large because of fat accumulation
|DMD appears typically in boys between ages 3 and 5 and progresses rapidly. Most people with DMD are unable to walk by age 12 and may later need a respirator to breathe. They usually die in their late teens or early 20s from heart trouble, respiratory complications, or infection.
||Also caused by a deficiency of dystrophin, and with symptoms similar to those of DMD, Becker can progress slowly or quickly.
||Patients with Becker MD may:
- Walk on their tiptoes
- Fall down a lot
Have difficulty rising from the floor
- Have cramping in their muscles
|Becker MD appears primarily in males between ages 11 and 25. Some people may never need to use a wheelchair, while others lose the ability to walk during their teens, mid-30s, or later.
|Myotonic (pronounced mahy-uh-TON-ik)
||The most common adult form of MD, myotonic MD appears in two forms, type 1 and type 2. Type 1 is more common and is caused by an abnormally large number of repeats of a three-letter "word" (CTG) in genetic code. While most people have up to 37 repeats of CTG, people with myotonic can have up to 4,000. The number of repeats may reflect the severity of symptoms.3
||Myotonic MD causes an inability to relax muscles following a sudden contraction. Other symptoms include
- Long, thin face and neck
- Swallowing difficulties
- Drooping eyelids, cataracts, and other vision problems
- Baldness at the front of the scalp
- Weight loss
- Increased sweating
- Heart problems that may lead to death during the 30s or 40s
- Irregular menstrual periods
|Myotonic MD affects both men and women between ages 20 and 30.
|Congenital (pronounced kuhn-JEN-i-tl)
||About half of all U.S. cases with congenital MD are caused by a defect in the protein merosin, which surrounds muscle fibers. When caused by defects in other proteins, this type of MD may also affect the central nervous system.4
||People with congenital MD may:
- Have problems with motor function and muscle control that appear at birth or during infancy
- Develop chronic shortening of muscles or tendons around joints, which prevents joints from moving freely
- Develop scoliosis (pronounced skoh-lee-OH-sis) (curvature of the spine)
- Have trouble breathing and swallowing
- Have foot deformities
- Have intellectual disabilities
|This form of MD appears at birth or by age 2. Congenital means "present from birth." Congenital MD affects both boys and girls, who often require support to sit or stand and may never learn to walk. Some patients die in infancy, but others live into adulthood with only mild disability.|
||Affecting boys primarily, the two forms of Emery-Dreifuss MD are caused by defects in the proteins that surround the nucleus in cells.5
||Weakness begins in the upper arm and lower leg muscles. People with this form may also
- Develop chronic shortening of muscles around joints (preventing them from moving freely), in the spine, ankles, knees, elbows, and back of the neck
- Have elbows locked in a flexed position
- Develop shoulder deterioration
- Have a rigid spine
- Walk on their toes
- Experience mild weakness in their facial muscles
|Symptoms usually begin by age 10 but can appear in patients up to their mid-20s. People with this form often develop heart problems by age 30, and they may die in mid-adulthood from progressive pulmonary or cardiac failure.
|Facioscapulohumeral (FSHD; pronounced fas-see-oh-skap-you-low-HEW-mur-l)
||FSHD refers to the areas affected: the face (facio), the shoulders (scapulo), and the upper arms (humeral). Researchers don’t know what gene causes FSHD. They do know where the defect occurs and that it affects specific muscle groups.6
||FSHD MD often appears first in the eyes (difficulty in opening and shutting) and mouth (inability to smile or pucker).7 Other symptoms may include
- Muscle wasting that causes shoulders to appear slanted and shoulder blades to appear "winged"
- Impaired reflexes only at the biceps and triceps
- Trouble swallowing, chewing, or speaking
- Hearing problems
- Swayback curve in the spine, called lordosis (pronounced lawr-DOH-sis)
|FSHD affects teen boys and girls typically but may occur as late as age 40. Most individuals have a normal life span, but symptoms can vary from mild to severely disabling.
||Affecting both males and females, different types of limb-girdle are caused by different gene mutations. Patients with limb-girdle inherit a defective gene from either parent, or, in the more severe form, the same defective gene from both parents.5
||Patients with limb-girdle MD may:
- First develop weakness around the hips, which then spreads to the shoulders, legs, and neck
- Fall down a lot
- Have trouble rising from chairs, climbing stairs, or carrying things
- Waddle when they walk
- Have a rigid spine
|This form of MD can appear in childhood but most often appears in adolescence or young adulthood. Limb-girdle can progress quickly or slowly, but most patients become severely disabled (with muscle damage and inability to walk) within 20 years of developing the disease.
||Distal MDs refer to a group of diseases that affect the muscles of the forearms, hands, lower legs, and feet. They are caused by defects in the protein dysferlin5 and can occur in both men and women.
||Distal MD may cause:
- Inability to perform hand movements
- Difficulty extending fingers
- Trouble walking and climbing stairs
- Inability to hop or stand on the heels
|This form typically appears between ages 40 and 60. Distal MD is less severe and progresses more slowly than other forms of MD, but it can spread to other muscles. Patients may eventually need a ventilator.
|Oculopharyngeal (pronounced ah-kyou-low-fuh-RHIN-ghee-l)
||This form occurs in both men and women, and it can be mild or severe. It is caused by a defect in a protein that binds to molecules that help make other proteins. It is common among Americans of French-Canadian descent, Jewish Ashkenazi, and Hispanics from the Southwest region.8
||Oculopharyngeal MD may cause:
- Drooping eyelids and other vision problems
- Swallowing problems
- Muscle wasting and weakness in the neck, shoulders, and sometimes limbs
- Heart problems
|This form of MD typically appears in a person’s 40s or 50s. Some people will eventually lose their ability to walk.