LAMA2-CMD is the result of genetic mutations of the laminin protein. LAMA2-CMD is caused by two mutations in the LAMA2 (laminin alpha 2) gene that produces merosine, one of the laminin proteins.

Affected people with LAMA2-CMD are born with complete or partial merosine deficiency, depending on where the genetic mutations are located. In those with complete merosine deficiency, hypotonia (decreased muscle tone or laxity) and progressive joint contractures are evident, and breathing and feeding problems may occur early in life. Scoliosis and a stiff spine may develop. In some cases, a seizure may occur due to the heart, and in others due to white matter abnormalities in the brain. 

In those with partial merosine deficiency, the disease may have a later or milder onset (late childhood / early adulthood). Symptoms may be milder.  

LAMA2-CMD is inherited in an autosomal recessive manner, meaning that there must be two pathogenic mutations present to cause symptoms. These mutations can be inherited from each parent or can be denovo (spontaneous).