The condition is caused by a recessive gene. This means that one abnormal copy of the gene is passed from each parent to the affected child, who in turn will have inherited two abnormal copies of the gene.
The risk for both carrier parents to have an affected child is 1:4 for each pregnancy.
People who have McArdle disease do not usually pass the condition onto their own children because one normal copy of the gene will have been provided by their partner. However, all of their children will be carriers. Generally speaking carriers do not have symptoms.