Note: Funding Information: The authors thank Stichting Smith Magenis Syndroom Nederland, the Dutch SMS support organization, for their support of our work. This research was financially supported in part by the Dutch National Institutes of Health (ZonMw), Grant/Award Number: #845006105. Funding Information: The authors thank Stichting Smith Magenis Syndroom Nederland, the Dutch SMS support organization, for their support of our work. This research was financially supported in part by the Dutch National Institutes of Health (ZonMw), Grant/Award Number: #845006105.