Resources for cooking for Wilson's Disease?
When I saw this question a few months ago, I didn't want to answer it because:
cooking for people with any kind of nutritional disease is not only difficult, but also dangerous,
therefore, before you move on, please ensure:

You have to have more than a basic understanding of (bio)chemistry
You have to have more than a basic understanding of nutrition
You have to have more than a basic understanding of Databases
You have to consult your physician (in this case: your friend's endocrinologist) with any recipe that you come up with using the below method:

The best freely publicly available scientific source for nutrition is the United States Department of Agriculture's SR28 Database so start with reading the manual!
In this particular case of Wilson's disease, the NUTR_DEF 312 Cu is the one to look out for, so load the raw data files into your favourite RDBMS, delete all references in FOOD_DES that contain 312 and presto: you have a USDA database customised to your friend's disease!
Select any of the ingredients that are left in the database, and start coming up with safe and yummy recipes that you have to give to your friend's  endocrinologist to vouch for them before actually making them...  :)
Note 1: If you have multiple friends with multiple allergies and intolerances, you leave everything in the database and SELECT * FROM Food_Des WHERE Nutrient_No NOT IN (Nutrient, Nutrient, ... );
Note 2: I answered your question because I feel sorry for your friend and no one has even tempted to answer your question in the last few months that I can notice.
Note 3: No, Seasoned advice is not a recipe-writing service so don't bother asking for recipes, they're off-topic here!
Note 4: Yes, I'm a chemist and I help my cousin, who's a professional chef, come up with recipes for sick children's birthday parties, but I have her run any recipes by the child's doctor...