[1] Univ Leicester, Dept Genet, Leicester LE1 7RH, Leics, England
[2] Univ Washington, Dept Neurol, Seattle, WA 98195 USA
[3] Gladstone Inst Neurol Dis, San Francisco, CA USA
[4] Univ Calif San Francisco, Dept Biochem & Biophys, San Francisco, CA 94143 USA
[5] Univ Calif San Francisco, Dept Neurol, San Francisco, CA 94143 USA