[1] Childrens Hosp Westmead, Inst Neuromusc Res, Westmead, NSW 2145, Australia
[2] Lahey Clin Med Ctr, Dept Neurol, Burlington, MA USA
[3] Childrens Hosp Westmead, Dept Rheumatol, Sydney, NSW, Australia
[4] Childrens Hosp Boston, Dept Neurol, Boston, MA USA
[5] Harvard Univ, Sch Med, Boston, MA USA
[6] Univ Sydney, Fac Med, Sydney, NSW, Australia