Enhancer Regulation of OSR2 in Mandibular Incisor Agenesis Susceptibility

Mandibular incisors are the most frequently congenitally absent teeth in Asian populations, affecting mastication, speech, aesthetics, and oral and maxillofacial functions over the long term. However, the genetic etiology of mandibular incisor agenesis (MIA) remains obscure. In this study, we conducted the first genome-wide association study on MIA in a Chinese population and identified an enhancer variant, rs71514987, associated with an increased risk of MIA (odds ratio, 2.18; 95% CI, 1.83 to 2.58; P = 3.62 × 10^-19). Functional characterization indicated that the rs71514987 C allele reduced the binding affinity of GATA4 to the OSR2 promoter, leading to increased OSR2 expression via remote regulation. Notably, elevated OSR2 levels promoted cell proliferation but diminished cell differentiation, migration, and apoptosis capabilities in stem cells from human exfoliated deciduous teeth, as well as abnormal development of pharyngeal teeth in zebrafish models. Mechanistic experiments further revealed that OSR2 bound to the promoter region of CXCR4, promoting its transcription level in the GPCR pathway, thereby influencing odontogenic differentiation during tooth development. Our findings provide novel insights into the molecular etiology of MIA.