Healthy control individuals were recruited from the Philadelphia region through the Hospital's Health Care Network, including four primary care clinics and several group practices and outpatient practices that performed well child visits. Eligibility criteria for this study included both of the following: disease-free children (age range: 6–18 years) and parents of these children who had high-quality, genome-wide genotyping data from blood samples with no serious underlying medical disorder, including, but not limited to neurodevelopmental disorders, cancer, chromosomal abnormalities and known metabolic or genetic disorders. DNA samples from a small set of parents of the participating children were also genotyped and used to assess CNV heritability patterns. A total of 2026 individuals passed all quality control measures and qualified for the study. All participants and/or their parents signed an informed consent permitting the use of their genotypes and health-care records for the study. Ancestry informative markers available on the HumanHap550 BeadChip22 were used to evaluate these 2026 participants to confirm ethnicity.
