Jumping in here. Yes, CMT is also known as Hereditary Motor Sensory Neuropathy (HMSN). It affects the muscles and the nerves. (That's just a simple explanation.) CMT is a complicated syndrome. There are over 70 types identified so far and the number is growing. It is inherited.

HNPP (Hereditary Neuropathy with Liability to Pressure Palsies) is the opposite of CMT1A. Here is the home site for it:

http://www.hnpp.org/

CMT1A is a mirror image. It has an extra copy of PMP22 whereas HNPP has a deletion.

The site explains it well. There is DNA blood testing available for HNPP.