kinase. Other gene mutations may also contribute.
Though progression is usually slow, myotonic mus-
cular dystrophy affects other body systems as well.
Cataracts and diabetes are common.
Symptoms and Diagnostic PathIn most forms of muscular dystrophy, the primary
symptoms are muscle weakness and disturbances
of posture and gait (walking style). The diagnostic
path begins with detailed PERSONAL HEALTH HISTORY
and family health history. Because muscular dys-
trophies are inherited disorders, the family health
history is particularly important. A comprehensive
NEUROLOGIC EXAMINATION identifies the specific
symptoms, which helps narrow the diagnosis.
BLOODtests may show excessive proteins that indi-338 The Musculoskeletal System
MAJOR TYPES OF MUSCULAR DYSTROPHYType of Muscular Dystrophy Key Characteristics Inheritance Pattern
Duchenne’s most common type X-linked recessive
affects primarily muscles of the upper arms, upper legs, and
pelvic girdle
first symptoms usually appear between ages 2 and 6
myotonic affects primarily muscles of the face and neck, hands, and feet autosomal dominant
gastrointestinal, cardiac, EYE, neurologic, and endocrine
involvement later in the disease
first symptoms appear in adulthood
Becker’s affects primarily muscles of the upper arms, upper legs, and X-linked recessive
pelvic girdle
very similar to Duchenne’s with milder symptoms
symptoms begin in late childhood or early ADOLESCENCE
limb-girdle affects primarily the muscles of the pelvic girdle and shoulder autosomal recessive or
girdle autosomal dominant
symptoms begin in late adolescence or early adulthood
facioscapulohumeral affects primarily the muscles of the face, neck, and shoulders autosomal dominant
symptoms begin in late adolescence or early adulthood
congenital affects all skeletal muscles autosomal recessive
often affects the CENTRAL NERVOUS SYSTEM, causing seizures
symptoms are present at birth
oculopharyngeal affects the muscles of the eyelids and THROAT autosomal dominant
symptoms begin in middle to late adulthood
distal affects the forearms, hands, lower legs, and feet autosomal recessive or
symptoms begin in adulthood autosomal dominant
Emery-Dreifuss affects primarily the shoulders, upper arms, pelvis, and lower X-linked recessive
legs
symptoms typically appear first as contractures, then weakness
symptoms begin in late childhood or early adolescence