A genome-wide association study of third molar agenesis in Japanese and Korean populations

Tooth agenesis is the most common developmental anomaly of human dentition, occurring most often in the third molar (wisdom tooth). It is affected by genetic variation, so this study aimed to identify susceptibility genes associated with third molar agenesis. Examination of panoramic radiographs and medical history about third molar extraction were used to diagnose third molar agenesis. We then conducted a genome-wide association study of 149 cases with at least one-third molar agenesis and 338 controls from Japan and Korea using the Illumina HumanOmniExpress BeadChip. After rigorous quality-control filtering, approximately 550 000 single-nucleotide polymorphisms (SNPs) were analyzed in association tests with the status. We identified three SNPs showing evidence of association at P<1 × 10(-5) and 69 SNPs showing evidence of association at P<1 × 10(-4). SNP rs1469622, which maps to an intron of THSD7B (thrombospondin, type I, domain containing 7B) on chromosome 2, showed the strongest association (combined odds ratio=1.88, 95% confidence interval=1.43-2.47, P=7.5 × 10(-6)). The identified SNPs may be considered candidates for future replication studies in independent samples.