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TOPDECC-Trans-omics for Precision Dentistry and Early Childhood Caries: Genome-Wide Genotyping (CIDR) and Microbiome in the ZOE 2.0 Study

The ZOE 2.0 study is a cross-sectional genetic epidemiologic investigation of early childhood oral health, conducted in a state-wide, community-based, multi-ethnic sample of 3-5-year-old preschool-age children in North Carolina, United States. Between 2016-2019, 8,059 children were enrolled and 6,404 of them underwent comprehensive oral-clinical examinations that provided usable data on dental caries (i.e., early childhood caries; ECC) phenotypes. Saliva samples and supragingival biofilm samples were collected by 10 trained and calibrated examiners during the clinical encounters that took place in enrolled children's preschool (Head Start) centers. Specifically, the study enrolled participants and conducted clinical examinations in 260 Head Start centers that belonged to 34 Head Start programs in NC. 6,262 participants provided clinical data and had extracted DNA that met quantity and quality criteria for high-density genotyping and 6,144 of them were retained in the genome-wide association study (GWAS). Additional information on oral health-related behaviors, risk factors and self-reported outcomes was collected prior to the conduct of the clinical exam using self-administered questionnaires completed by children's guardians. Height and weight measurements were used to derive measures of adiposity. A domestic water sample for fluoride concentration measurement was obtained after the clinical examination for approximately 25% of study participants, to provide a measure of environmental exposure to this known caries-preventive agent and this information was subsequently imputed to the entire cohort using a novel GIS-informed method. Supragingival biofilm samples for microbiome analyses were collected from all participating children. Biofilm samples from a pilot 5% (n=300) of the cohort were carried forward to WGS (metagenomics; MTG) and RNAseq (metatranscriptomics; MTX) analyses, and these sequence data are being released via the Sequence Read Archive (SRA) in this dbGaP accession: 300 participants with MTG, 297 of those with MTX. Of note, the 17 participants with MTG data did not have genotypes produced, therefore the study's released participant total count is 6161, including 6144 (with genotypes released) plus 17 (with no genotypes released but with MTG data in the SRA).

The study's primary objective is to identify risk loci and gene sets/pathways for ECC and related traits (e.g., caries prevalence and severity) by conducting a trans-ethnic GWAS. Genotyping is based on the Infinium™ Global Diversity Array and the TOPMed panel is used for imputation via the University of Michigan Imputation server. Secondarily, the ZOE 2.0 seeks to determine prevalence and severity of dental caries, other oral disease outcomes, and putative risk factors for dental caries in this low-income population-based sample of European-, African-, and Hispanic/Latino-American preschool-age children.