Will general practitioners help in healing mccradle's disease?

No. I assume you are referring to the glycogen storage disease known as mcardle disease. There is no cure.
Yes. General or family physicians can assist you in caring for mcardle's disease in conjunction with a genetic specialist. Unfortunately this is a genetic disease with no known cure at this time. So treatment would be in managing the symptoms and complications as well as preventing the complications as much as possible. Of course these patients also get other problems that are assisted by gp's.