Dear Mary Ann , I am wondering if your nephew's condition could be methemoglobinemia , a condition involving unusually high levels of methemoglobin which greatly interferes with the blood's transport of oxygen . It can be both hereditary or induced by various means and is generally treated with methylene blue and possibly vitamin C . The most famous case involved the Fugates of Kentucky . An excellent link is http://www.people.virginia.edu/~rjh9u/fugate.html
Best of luck to you both .