1. Institute of Animal Physiology, Ludwig Maximilians University (R.G.E., K.W., U.Z.), 80539 Munich, Germany
2. Institute of Mammalian Genetics, GSF National Research Center for Environment and Health (D.W.S., R.B.), 85764 Neuherberg, Germany
3. National Center for Scientific Research, UPR 1524, National Institute of Agricultural Research (M.L.), 78 350 Jouy-en-Josas, France
4. Department of Dermatology D92, Bispebjerg Hospital (R.G.), 2400 Copenhagen NV, Denmark
5. Institute of Experimental Genetics, GSF National Research Center for Environment and Health (G.M., J.A.), 85764 Neuherberg, Germany