Author Contributions: Dr van Maldegem had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: van Maldegem, Wanders, Wijburg.
Acquisition of data: van Maldegem, Niezen-Koning, Hogeveen.
Analysis and interpretation of data: Duran, Ijlst, Waterham.
Drafting of the manuscript: van Maldegem, Wanders, Wijburg.
Critical revision of the manuscript for important intellectual content: Duran, Niezen-Koning, Hogeveen, Ijlst, Waterham.
Statistical analysis: van Maldegem.
Obtained funding: van Maldegem, Wijburg.
Administrative, technical, or material support: van Maldegem, Duran, Niezen-Koning, Hogeveen, Ijlst, Waterham.
Study supervision: Wanders, Wijburg.
Financial Disclosures: None reported.
Funding/Support: This work was supported by a research grant to Drs van Maldegem and Wijburg from the “Metabole Fonds” of the Academic Medical Center, Amsterdam.
Role of the Sponsor: The research sponsor had no role in the design and conduct of the study; collection, management, analysis and interpretation of the data; or preparation, review, or approval of the manuscript.
Acknowledgment: We thank H. D. Bakker, MD, PhD, P. G. Barth, MD, PhD, R. F. M. de Coo, MD, PhD, P. M. van Hasselt, MD, PhD, J. B. C. de Klerk, MD, PhD, T. J. de Koning, MD, PhD, E. Langius, MD, PhD, S. M. Maas, MD, PhD, J. P. Rake, MD, PhD, M. E. Rubio-Gozalbo, MD, PhD, G. P. A. Smit, MD, PhD, M. E. J. Wegdam-den Boer, MD, PhD, and J. M. B. Wennink, MD, PhD, for providing data on their patients, N. G. G. M. Abeling for assistance on biochemical analyses, and J. H. van der Lee, MD, PhD, of the Centre for Pediatric Clinical Epidemiology for assistance on statistical analyses.