Some conditions are severe and life-threatening, others are milder ,a few are treatable.
All these conditions are characterised by muscular weakness though its degree is variable. Dysfunction may occur in any part of the unit. Regeneration of the damaged muscles is inadequate and muscle is gradually replaced by fibrous tissue and fat. These are variable and depend upon the specific condition. This is available where gene marker tests have been done prior to pregnancy and where the gene has been identified or markers are close to the gene site.