This is a repost of my first response, which was deleted because it contained a link to a commercial site.
There are several different subtypes of Waardenburg Syndrome. If you know which type, I can tell you a little bit more.http://www.ncbi.nlm.nih.gov/sites/GeneTests/lab/disease/Waar...
I researched an autosomal dominant hearing impairment in my own family with a combination of genealogy and autosomal DNA testing at 23andMe. The gene was unknown in our case, but we think we have narrowed down the possibilities. I wrote about this on the 23andMe blog:
[link omitted -- you can find the post by Googling these keywords
turner "tracking down a trait" ]
It sounds like you might have enough family members to conduct similar research yourself.