Bethlem myopathy


Bethlem myopathy (also known as benign congenital muscular dystrophy or benign congenital myopathy with contractures) is a condition that mainly affects skeletal muscles, which are the muscles used for movement. People with this condition experience progressive muscle weakness and develop joint stiffness (contractures) in their fingers, wrists, elbows, and ankles that can restrict movement. Approximately two-thirds of people with Bethlem myopathy over age 50 will need to use a walker or wheelchair.


Source: Genetics Home Reference



The features of Bethlem myopathy can appear at any age. Some individuals have signs of the disorder even before birth, most commonly decreased fetal movement. Other affected individuals develop symptoms soon after birth, including low muscle tone and a stiff neck that causes the head to lean to one side (torticollis). People whose symptoms appear in childhood may experience delayed developmental milestones, such as sitting or walking. Others do not develop features of the condition until late adulthood.

Some people with Bethlem myopathy have skin abnormalities such as small bumps called follicular hyperkeratosis that develop around the elbows and knees; soft, velvety skin of the palms and soles; and wounds that split open with little bleeding and widen over time to create shallow scars.

 Source: Genetics Home Reference


Mutations in the COL6A1, COL6A2, and COL6A3 genes cause Bethlem myopathy. These genes each provide instructions for making one component of a protein called type VI collagen. This protein plays an important role in muscle, particularly skeletal muscle.

Type VI collagen makes up part of the extracellular matrix that surrounds muscle cells. The extracellular matrix is an intricate lattice that forms in the space between cells and provides structural support. The extracellular matrix that surrounds muscle cells is necessary for muscle cell stability and growth.

Mutations in the type VI collagen genes that cause Bethlem myopathy result in the formation of abnormal type VI collagen or reduce the amount of type VI collagen that is produced. A decrease in normal type VI collagen disrupts the extracellular matrix surrounding muscle cells, leading to progressive muscle weakness and the other signs and symptoms of Bethlem myopathy.



List of diagnostic laboratories for genetic diseases can be found at NCBI homepage in GeneTests section


Source: NCBI


Currently there are no treatments available for Bethlem Myopathy, except for Physical Therapy.

Researches in Europe are looking at the drug cyclosporin A as a potential treatment. 


Source: Muscular Distrophy Campaign