[1] GSF, Natl Res Ctr Environm & He, Clin Cooperat Grp Leukemia, Munich, Germany
[2] Univ Hosp Grosshadern, Dept Med 3, Munich, Germany
[3] Harvard Univ, Sch Med, Howard Hughes Med Inst, Boston, MA 02115 USA
[4] Harvard Univ, Brigham & Womens Hosp, Sch Med, Boston, MA 02115 USA