I've done a lot of research on MD and here are some facts they I've came up with. I hope it's as helpful to you as it was to me :-)
What Is Muscular Dystrophy? The term Muscular Dystrophy refers to a group of 40 known neuromuscular diseases which cause progressive wasting of the skeletal or voluntary muscle tissue.
What Causes Muscular Dystrophy? MD is caused by defects in genes for muscle proteins. Research has found that there are about 3,000 muscle proteins and the chemical DNA (the "code" for a protein) for each is contained in a separate gene (each cell in our body contains thousands of genes), however in some cases the code is wrong... making the protein wrong, in the wrong amount, or some contain no protein at all. The defect in the muscle protein gene can influence the nature and severity of a muscle disease, for example... defects in the dystrophin gene causes the most severe muscle wasting known as Duchenne muscular dystrophy.
In most cases, MD is generally inherited in either a autosomal dominant, autosomal recessive or X-linked recessive manner. Autosomal dominant manner of inheritance is when only one parent passes on the defective gene. In this case offspring have a 50 percent chance of inheriting the autosomal dominant disease.
Autosomal recessive manner of inheritance is when both parents pass on the same or similar gene defect. In this case offspring have a 25 percent chance of inheriting both flawed genes and developing the disease
X-linked recessive manner of inheritance is when the diseases come from gene defects in the X chromosome. Because males have only one X chromosome, these disorders primarily effect males.