[1] Univ Western Australia, Ctr Child Hlth Res, Telethon Inst Child Hlth Res, Perth, WA 6872, Australia
[2] Univ Chicago, Comer Childrens Hosp, Kennedy Ctr Intellectual & Dev Disabil, Inst Mol Pediat Sci, Chicago, IL USA
[3] Univ Chicago, LaRabida Childrens Hosp, Kennedy Ctr Intellectual & Dev Disabil, Inst Mol Pediat Sci, Chicago, IL USA
[4] Univ Chicago, Sect Dev & Behav Pediat, Chicago, IL USA
[5] Curtin Univ Technol, Sch Publ Hlth, Perth, WA, Australia
[6] Univ Paris 05, INSERM, U663, Necker Enfants Malad Hosp Paris, F-75270 Paris 06, France
[7] Kennedy Krieger Inst, Ctr Genet Disorders Cognit & Behav, Baltimore, MD USA
[8] Johns Hopkins Univ, Sch Med, Baltimore, MD USA