TRENTON, N.J. - For eight months during his infancy, Sean Van Duyn gagged, retched and vomited daily. Now 6, the Winter Haven, Fla., boy still can't eat or drink by mouth, instead being fed by a permanent tube in his belly. Beset by multiple medical problems in his first months, the boy had to have a breathing tube inserted through a hole cut in his neck. The gagging began and continued until his mother, Susan, discovered the tube was misshaped at the end and had been poking the back of his throat the whole time. The tube was replaced, but...