Bethlem myopathy

Disease Overview

Bethlem myopathy is a rare disease affecting the skeletal muscles and connective tissue. The disease is characterized by slowly progressive muscle weakness and joint stiffness (contractures). It most often affects the fingers, wrists, elbows, and ankles.[8210][8211] Signs and symptoms may begin before birth (with decreased fetal movements), shortly after birth (with low muscle tone or torticollis), in early childhood (with delayed motor skills, muscle weakness, and contractures), or in adulthood (with weakness, Achilles tendon, or finger contractures). Due to the disease’s progression, most people with Bethlem myopathy over age 50 require mobility aids (such as a cane, crutches, or wheelchair) for outdoor mobility. Rarely, severe muscle weakness may lead to respiratory difficulties in later life.[8211]
 
Bethlem myopathy is caused by mutations (changes) in the COL6A1, COL6A2, or COL6A3 genes. Most cases are inherited in an autosomal dominant manner, but in rare cases the disease is autosomal recessive.[8210][8211] The diagnosis is based on clinical examination and laboratory tests, but genetic testing may confirm the diagnosis.[8211] Treatment depends on individual symptoms but routinely involves physical therapy. Surgery to correct joint contractures may be needed.[8211]

Synonyms

• Myopathy, benign congenital, with contractures
• Muscular dystrophy, benign congenital