Watch the diet. Most babies with galactosemia do great if they stick to a specific diet. In particular, avoiding regular cow's milk is very important. For this condition, soy is a good option. Also, working with a genetic nutritionist who can make recommendations on which foods to avoid once your baby is eating solid foods will help to avoid problems due to this enzyme deficiency.
Special diet. http://www.nlm.nih.gov/medlineplus/ency/article/000366.htm avoid dairy products including breast milk; soy or meat based formulas are ok.