[1] Whitehead Inst, Cambridge, MA 02142 USA
[2] MIT, Dept Biol, Cambridge, MA 02139 USA
[3] MIT, Computat & Syst Biol Program, Cambridge, MA 02139 USA
[4] Sangamo BioSci Inc, Pt Richmond Tech Ctr, Richmond, CA 94804 USA
[5] Harvard Univ, Sch Med, Brigham & Womens Hosp, Dept Neurol, Boston, MA 02115 USA
[6] Harvard Univ, Sch Med, Massachusetts Gen Hosp, Dept Neurol, Boston, MA 02115 USA
[7] Boston Univ, Sch Med, Dept Neurol, Boston, MA 02118 USA
[8] Univ Med & Dent New Jersey, Robert Wood Johnson Med Sch, Dept Neurol, New Brunswick, NJ 08903 USA