BMD) Affects Males, While Females Typically Is a Genetic Disorder Characterized by Are Carriers

A Guide for Individuals and Families

Becker muscular dystrophy (BMD) affects males, while females typically is a genetic disorder characterized by are carriers. Some females can progressive weakness and degeneration of experience varying ranges of physical the skeletal muscles that control movement. symptoms, including muscle weakness Heart muscle also is commonly affected, and cramps, and are therefore called making cardiac problems a prominent manifesting carriers. feature of the disease. There are approximately 11,000 people living BMD typically is inherited through the with either BMD or DMD in the United States. mother; however, in some of cases, it occurs spontaneously in people who do BMD is classified as adystrophinopathy , not have a family history of the disease. a muscle disease that results from the deficiency of a protein called dystrophin. There is no cure for BMD, but medications, assistive devices, and therapy can help In both Duchenne muscular dystrophy (DMD) manage some symptoms and improve and BMD, a variation in the quality of life. DMD gene interferes with production of the dystrophin protein, a critical component in the formation and mainte- nance of healthy muscle. A BMD-causing gene variant typically leads to an abnormal version of the dystrophin protein that is only partially functional. However, lack of fully functional dystrophin protein in muscle cells causes them to be fragile and become damaged with use.

Because the DMD gene is located on the X chromosome, BMD primarily What are the signs and symptoms of BMD? BMD is a multi-systemic condition, affecting many parts of the body and resulting in atrophy of the skeletal, cardiac (heart), and pulmonary (lung) muscles.

Nervous system • Developmental delay • Motor delay Skeleton and muscle • Muscle weakness • Reduced stamina Cognition • Fatigue • Gait abnormalities • Learning disability • Loss of balance • Walking on the • Behavioral deficits • Impaired coordination tips of toes • Muscle cramps • Contractures Gastrointestinal • Difficulty walking • Pseudohypertrophy • Dysphagia • Difficulty climbing stairs • Lordosis • Constipation • Exercise intolerance • Scoliosis • Reflux • Gastroparesis Heart Lungs • Cardiomyopathy • Congestive heart failure • Breathing difficulties • Arrhythmias • Respiratory infections • Swelling in the feet and lower • Sleep apnea legs

What should I know about BMD?

1 BMD is closely related to Duchenne 4 In some cases, the first sign of 7 Other symptoms of BMD can include muscular dystrophy (DMD), which is disease may be a heart condition cognitive problems, fatigue, loss of caused by different variations in the called dilated cardiomyopathy. balance and coordination, and same gene. Because disease progres- This form of heart disease enlarges breathing problems. A small sion and treatment plans differ be- and weakens the heart muscle, percentage of boys with the disease tween the two disorders, a BMD diag- preventing it from pumping blood have some degree of learning nosis should be confirmed with efficiently. Dilated cardiomyopathy disability, including problems in three genetic testing. progresses rapidly and can be general areas: attention, verbal life threatening. learning and memory, and emotional interaction. 2 A defining feature of BMD is a high degree of variability in symptoms—in- 5 Skeletal muscle weakness often cluding onset, severity, and correlation begins in the legs and pelvic area 8 The diaphragm and other muscles and slowly progresses to the between symptoms—and rate of dis- involved in breathing typically ease progression from one individual muscles of the shoulders, neck, weaken, making the lungs less to another. Although both skeletal and arms, and respiratory system. Over effective at moving air in and out. cardiac (heart) muscle typically are af- time, affected individuals begin to fected, there is no have difficulty walking, running, Signs of poor respiratory function apparent association between the hopping, and jumping, and they may can include headaches, difficulty two. So, a boy could experience any have frequent falls. Although loss of concentrating or staying awake, and range of skeletal muscle weakness, muscle mass is common, the calves nightmares. Weakened respiratory from mild to severe, paired with any may become enlarged. muscles also make level of cardiac involvement; the char- it difficult to cough, leading to acter of one does not correlate with increased risk of serious the other. 6 Some individuals with BMD will have respiratory infection. problems getting up from the floor and may use a distinctive method 3 Muscle weakness can begin at any known as Gower’s maneuver or 9 Medical and scientific advances are time from childhood into the early Gower’s sign to helping to improve quality of life, and 20s, but it usually becomes apparent “walk” their hands up their people with BMD often survive into between the ages of 5 and 15 years. thighs in order to stand up. their 40s and beyond. How is BMD treated?

Over-the-counter pain Educational and psychological relievers may be used to interventions can help with treat muscle pain or cramps. learning disabilities.

Wheelchairs or scooters Occupational therapy can may be used to help help improve daily living maintain mobility. and work skills.

Braces, also called orthoses, support the ankle and foot or Corticosteroids (such as may extend up over the knee. prednisone and Emflaza) Ankle-foot orthoses (AFOs) may be prescribed in BMD are sometimes prescribed for to help preserve muscle night wear to keep the foot from strength and function, to pointing downward and keep prevent scoliosis, and to the Achilles tendon stretched prolong the time that people while a child is sleeping. with BMD can walk. It’s thought that they work, at Physical therapy through least in part, by reducing exercise helps to restore inflammation. However, and maintain muscle corticosteroids also cause strength and function. Corrective orthopedic unwanted side effects Stretching helps to maintain surgery, including spine- such as increased appetite, range of straightening surgery, weight gain, motion. may help make sitting, loss of bone mass, sleeping, and breathing and cataracts. more comfortable.

Speech therapy can help with swallowing problems.

Assisted ventilation can help treat respiratory muscle weakness.

Treatment with angiotensin converting enzyme (ACE) inhibi- tors and beta blockers may be used to slow the course of cardiac muscle deterioration in BMD. Cardiac evaluations are recommended beginning at around 10 years old, or when symptoms first begin, and be repeated at least every two years. Please talk to your medical provider to obtain more information on these treatments. MDA Glossary

Atrophy Gower’s maneuver A decrease in the size and mass of muscle A person’s use of their hands and tissue arms to “walk” up their own body in order to rise from a squatting position; indicates Cardiomyopathy weakness of the muscles in the hips and A condition in which the heart muscle legs is weakened, making it harder for the heart to pump blood to the body Lordosis Posture characterized by an inward Contracture curving of the lower back A shortening of muscles or tendons around joints that can limit mobility Muscular dystrophy A term that refers to a number of diseases Corticosteroid that cause progressive loss One of a group of steroid hormones of muscle mass, resulting in weakness that has been shown to dampen the and sometimes, loss of mobility inflammatory response in damaged muscle Pseudohypertrophy A condition in which muscles become Dysphagia enlarged with deposits of fat and Difficulty swallowing fibrous tissue

Gastroparesis Scoliosis A condition that affects the ability of An abnormal sideways curvature the stomach to empty its contents into the in the spine that occurs when small intestine, even though there is no weakened muscles are unable to blockage; also known as delayed gastric hold the spine straight emptying

Gene variant A flaw in the DNA code

To learn more about BMD, visit mda.org or contact the MDA Resource Center at 833-ASK-MDA1 (275-6321).

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66-0015 June 2021