[1] Univ Amsterdam, AMC, Dept Paediat, NL-1012 WX Amsterdam, Netherlands
[2] Pitt Hopkins Parents Support Grp, Leidschendam, Netherlands
[3] Cornelia Lange Syndrome Support Grp, Ijmuiden, Netherlands
[4] Marshall Smith Syndrome Fdn, The Hague, Netherlands
[5] Univ Amsterdam, Acad Med Ctr, Dept Paediat & Translat Genet, NL-1105 AZ Amsterdam, Netherlands