CMT, multiple sclerosis, and muscular dystrophy are all three completely separate and distinct problems. Remember that our neuromuscular system really starts at the brain, which is the master computer, and sends signals to the motor (muscles) via the spinal cord (an intermediate connecting cable) which hooks up to the peripheral nerves (the connecting lines between brain and muscle).

For the sake of understanding, I will simplify this a bit: I think everyone who reads this newsletter knows what CMT is but for those who don't, it is primarily a disease of the peripheral nerves (the connecting lines between brain and muscle). CMT causes weakness and impaired sensory perception because the signal can't get to and from the brain to muscle and skin, among other things. The muscles will shrink as they aren't getting the proper signals but the muscles themselves are not directly diseased per se.

Muscular dystrophy is a disease directly of the muscle itself and this causes weakness of varying degrees (there are many forms of MD). Sometimes the heart can be involved because it is a muscle too. Also, the lungs can be affected because the breathing muscles are weak (similar to CMT, although in CMT it is because the phrenic nerves are affected which in turn weakens the diaphragm, our main breathing muscle).

Multiple sclerosis is a disease of the brain and spinal cord. It can affect both movement and sensory perception and sometimes, thinking processes.
Now we can go on and on about more subtle distinctions, but I think that if one can understand those differences then you should be able to know most of where the problems lie in these disease processes.