[1] Univ Calif Davis, Sacramento, CA USA
[2] Childrens Natl Med Ctr, Ctr Genet Res, Washington, DC 20010 USA
[3] Childrens Natl Med Ctr, Cooperat Int Neuromuscular Res Grp, Washington, DC 20010 USA
[4] Alberta Childrens Prov Gen Hosp, Edmonton, AB, Canada