myotonic dystrophy
Quick Summary
Myotonic dystrophy is a group of inherited muscular disorders characterized by myotonia, which is the difficulty in relaxing muscles after contraction. This condition is the most common muscular dystrophy affecting adults.123
Pathology
Myotonia often results from genetic mutations affecting ion channels in muscle cells, specifically the CLCN1 gene which controls chloride channels, or the SCN4A gene for sodium channels. These defects disrupt ion flow, causing muscles to contract for extended periods. In myotonic dystrophy, this is accompanied by progressive muscle weakness and degeneration, affecting multiple body systems beyond just the muscles.1243
Symptoms and Types
Symptoms can include premature balding, cataracts, mental impairment, and heart problems. There are different types, including myotonic dystrophy type 1 and type 2, which vary in severity and age of onset. Unlike some other muscular dystrophies, muscles in myotonic dystrophy degenerate rather than overdevelop.231
Ask Britannica AI about this topic
Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.
- myotonia
Myotonia congenita and myotonic muscular dystrophy are usually caused by a mutation or other abnormality in a gene known as CLCN1 (chloride channel 1, skeletal muscle). That gene normally produces a protein that controls chloride channels in skeletal muscle fibre cells. However, defects in CLCN1 disrupt ion flow,
Read MoreMyotonia congenita and myotonic muscular dystrophy are usually caused by a mutation or other abnormality in a gene known as CLCN1 (chloride channel 1, skeletal muscle). That gene normally produces a protein that controls chloride channels in skeletal muscle fibre cells. However, defects in CLCN1 disrupt ion flow,
Read More 
muscle diseaseMyotonic diseasesMyotonic dystrophy is the most common of the myotonic disorders. It is an autosomal dominant disorder affecting many systems of the body in addition to muscle. Symptoms include premature balding, cataract formation, mental impairment, gonadal atrophy, endocrine deficiencies, gastrointestinal tract dysfunction, and muscle fibre degeneration.…
Read MoreMyotonic dystrophy is the most common of the myotonic disorders. It is an autosomal dominant disorder affecting many systems of the body in addition to muscle. Symptoms include premature balding, cataract formation, mental impairment, gonadal atrophy, endocrine deficiencies, gastrointestinal tract dysfunction, and muscle fibre degeneration.…
Read More
nervous system diseaseGenetic dystrophiesMyotonic dystrophy is characterized by weakness and wasting of the face and trunk muscles. In addition, muscles fail to relax after a strong contraction, so that, for example, the patient cannot easily let go after shaking hands. Involvement of other body systems is common. The…
Read MoreMyotonic dystrophy is characterized by weakness and wasting of the face and trunk muscles. In addition, muscles fail to relax after a strong contraction, so that, for example, the patient cannot easily let go after shaking hands. Involvement of other body systems is common. The…
Read More