If we need help for our child is it possible to contact a foundation that deals with the disease?

More than likely. Almost any condition that affects children will have a foundation dedicated to it. If not, there will certainly be an "interest group" composed of other parents who have children with similar problem. An internet search on a search engine like google would be the place to start. Also, contact the nearest children's hospital. Organizations like easter seals can also help.
Absolutely. There are countless organizations available to patients and their parents, depending on how common the illness may be. Speak to your physician regarding the diagnosis and support organizations that are available.
YES. Depending on the child's problem, there is a foundation that can help.