The structure and evolution of the human beta-globin gene family. by Efstratiadis, A, Posakony, J, Maniatis, T, Lawn, R, O'Connell, C, Spritz, R, DeRiel, J, Forget, BG, Weissman, S, Slightom, J, Blechl, A, Smithies, O, Baralle, F, Shoulders, C, Proudfoot, N