Congenital muscular dystrophies (CMDs) is the name given to a group of muscular dystrophies that lead to muscle weakness and wasting from birth or very early on in life. CMDs are caused by genetic mutations that may be inherited or be the result of new mutations.
There are several different types of CMDs, summarized below.
Bethlem myopathy is a rare and progressive form of CMD with fewer than 100 cases reported.
Symptoms of Bethlem myopathy can start before birth when the fetus shows decreased movement in the womb.
Infants with Bethlem myopathy show hypotonia (low muscle tone or floppiness) and torticollis (stiff neck). Children often experience delayed muscle development — learning to sit and walk later than normal. Contractures (tightness) in the tendons may be observed at any time. Breathing problems are usually rare in patients with Bethlem myopathy.
Many patients with Bethlem myopathy develop a type of wasting called cachexia.
Fukuyama congenital muscular dystrophy
Infants born with FCMD have weak muscle tone from birth (hypotonia) and exhibit weak crying and suckling. The facial muscles may also be weak. FCMD can also impair brain development, which can delay the development of speech. Children with FCMD may have severe intellectual disabilities, and many also experience seizures. They also can have impaired vision, eye abnormalities, and progressive heart conditions.
Muscle-eye-brain diseases (MEBs) occur primarily in Finland and affect skeletal muscles, eyes, and the brain, as the name suggests. Infants born with this disease usually have hypotonia, cognitive disability, intellectual disability, and severe developmental delays. Children with the disease may also develop eye problems such as nearsightedness and glaucoma (high pressure in the eye that can cause blindness).
Rigid spine muscular dystrophy
Rigid spine muscular dystrophy (RSMD) is a rare type of CMD with unknown frequency.
Infants with RSMD display muscle weakness at birth or within the first few months of life. Over time, the muscles around the spine weaken. The joints of the spine where the vertebrae meet develop abnormalities called contractures, which restrict movement and make the neck and back stiff and rigid. Some patients also develop scoliosis, an abnormal curvature of the spine. Due to these back problems and muscle weakness, children with the disease often have difficulty breathing, especially at night.
Ullrich congenital muscular dystrophy
Ullrich congenital muscular dystrophy (UCMD) is characterized by hypotonia at birth, as well as poor head control. In addition to muscle weakness, there may be hypermobility in the finger and wrist joints allowing too much movement. Children have tightness in the hips, knees, and elbows, and some may also develop scoliosis.
Walker-Warburg syndrome (WWS) is a rare form of CMD. While the worldwide incidence is not known, a small Italian study indicated that it occurs in slightly more than 1 in 100,000 births.
Infants born with WWS display hypotonia, which worsens over time. The disease also causes brain abnormalities, which can cause delayed development, intellectual disability, and seizures.
WWS can cause eye abnormalities, but these can vary between individuals. Some infants may have unusually small or enlarged eyeballs; others may develop cataracts (clouding of the lenses of the eye), or problems with the nerves of the eye. The eye abnormalities caused by WWS result in vision impairment.
Last updated: Aug. 26, 2019
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