Hi,
When you mentioned the PMP22 gene it rang a bell. A person who has CMT type 1A has a duplication of it. If there is a deletion then that would indicate HNPP (Hereditary Neuropathy with Liability to Pressure Palsy). Interesting. Here is a site concerning it.
http://www.ncbi.nlm.nih.gov/pubmed/14555828
Also, I do believe IVIG is for autoimmune diseases which the two above are not. What are your symptoms if you care to share. Hope you find the answer and thank you.