If you are affected by CMD please register TODAY on the CMD Registry: www.cmdir.org

Background

The muscular dystrophies are a group of genetic diseases that cause weakness and muscle wasting, primarily in the skeletal or voluntary muscles (those we control such as the muscles of the arms and legs).

All the forms of muscular dystrophy are inherited - that is, they're caused by mutations (changes) in a person's genes. Our genes are made of DNA and they reside in our chromosomes. Each gene contains the "recipe" for a different protein and its variations, and these proteins are necessary for our bodies to function correctly.

When a gene has a mutation, it may make a defective protein or none at all. Most commonly, missing or defective proteins in the muscles prevent muscle cells from working properly, leading to symptoms of muscular dystrophy, including muscle weakness and wasting over time.

Muscles are made up of bundles of fibers (cells). Groups of proteins along the membrane surrounding each fiber and within the cell help to keep muscle cells working properly. When one of these proteins is absent or inadequate (because a gene fails to make it properly), the result can be a form of muscular dystrophy. Absence of or defects in different proteins are among the causes of different types of muscular dystrophy.

Congenital Muscular Dystrophy (CMD)

The term congenital muscular dystrophy (CMD) is actually the name for a group of muscular dystrophies that are united by the fact that muscle weakness begins in infancy or very early childhood (typically before age 2). Congenital diseases are those in which the symptoms are present at, or soon after birth.

Although children with CMD can have different associated symptoms, degrees of severity and rates of progression, most exhibit some progressive muscle weakness. This weakness, usually first identified as hypotonia, or lack of muscle tone, can make an infant seem "floppy." Later, infants and toddlers may be slow to meet motor milestones such as rolling over, sitting up or walking, or may not meet some milestones at all.

It isn't known why the CMDs cause muscle weakness earlier than other types of muscular dystrophy. One possibility is that the muscle proteins affected in CMD are required early in the development of an infant's muscle, while muscle proteins linked to other muscular dystrophies don't become important until the muscles begin to get a lot of use as a child grows.

The following informative factsheets have been kindly provided courtesy of the Muscular Dystrophy Campaign.

• SAM CMDIR Leaflet (pdf)
• Congenital Muscular Dystrophy Factsheet (pdf)
• MDC1A Factsheet (pdf)
• Ullrich MD Factsheet (pdf)
• RSMD1 Factsheet (pdf)
• LGMD2A Factsheet (pdf)