Child DNA was collected via buccal cells by brushing the inside of the cheek with a buccal brush. Participants were instructed to gently rub the inside of each cheek with separate buccal brushes for approximately 30 seconds. The brushes were then placed in individual plastic cylinders marked with the participant’s study ID number for storage and transport. Following collection, the cylinders were temporarily stored in a research lab refrigerator, then were transported to the Genomics Core Facility at the University of Alabama at Birmingham for genotyping. Parents and children each received $5 for participating in the collection of DNA. Figure 1 indicates the number of participants who declined to provide DNA or whose DNA was not usable.
