Re: Is it likely my expected grandchild will inherit CMT Disease?

  Hello Cindy.  I'm sorry it's taken me so long to answer your question.  
I've looked into the inheritence patterns of CMT on the Mendelian 
inheritence in man website.   http://www.ncbi.nlm.nih.gov/Omim/
  This is the foremost web database for all of the genetic diseases 
identified to date.  Unfortunately, for CMT, there are many different ways 
that the disease is transmitted and we can't be sure of what form of CMT 
your sons wife has.  It looks like CMT can be transmitted either autosomal 
dominantly, autosomal recessively, or X-linked dominantly.  The autosomal 
recessive form of CMT is the rarest.  Also, according to the limited 
pedigree you gave for your daugter in law's parents, it would tend to rule 
out the autosomal recessive version of the disease.  
  Should the disease be autosomal dominant in your daughter in law, then 
there would be a 50/50 chance of their child inheriting the disease, like 
you said.  If it were an x-linked dominant, then it would also be a 50/50 
chance for both a daughter or son.
   I would recommend you seek genetic counseling if you would really like a 
thorough analysis of the chances, since it's impossible to really analyze 
this with the limited pedigree you've given.  Also, some of the genes 
involved in CMT disease are known, and it may be possible to test for 
mutations in your daughter in law that might let you all know exactly which 
CMT form she carries.