Non-syndromic cleft lip with or without cleft palate (NSCL/P) is a complex disease with a strong genetic component. More than 40 loci have been identified to be associated with the risk of NSCL/P by genome-wide association studies (GWASs), but the majority of these variants are mapped to non-coding regions of the genome. Expression quantitative trait locus (eQTL) studies have increasingly been integrated with GWASs to identify target genes for these non-coding variants. In this study, we generated a unique, lip-specific eQTL dataset from 40 NSCL/P patients. A total of 5158 eQTL SNPs (eSNPs) -689 eQTL genes were identified after multiple corrections. Then, we integrated nominal eQTL SNPs with NSCL/P risk SNPs and identified 243 variants associated with the expression of 18 genes in lip tissues. Functional annotation analysis indicated that these risk eSNPs were significantly enriched in transcription regulation and chromatin open regions on the genome. These susceptible genes were enriched in cell fate determination, the pluripotency of stem cells, and Wnt signaling pathways. Finally, 8 of the 18 susceptible genes were differentially expressed in NSCL/P case-control studies. In summary, we have generated a unique lip-specific eQTL resource and identified multiple associations for NSCL/P risk loci, which should inform functional studies of NSCL/P biology.

Skeletal Class III malocclusion with maxillary deficiency is a severe maxillofacial disease with unclear pathogenic mechanisms. We recruited a Han Chinese family who was clinically diagnosed with skeletal Class III malocclusion and maxillary deficiency. Using whole exome sequencing, a missense variant in ADAMTS2 (NM_014244: c.3506G>T: p.G1169V) was identified and predicted as deleterious by in silico tools. We also found ADAMTS2 variants associated with deficient maxillary development in a cohort. ADAMTS2 expression in HEK293 cells showed significant decrease due to the variant, which was also consistent in dental pulp stem cells from the proband and a healthy control. In the adamts2-knockdown zebrafish model, the length and width of the ethmoid plate, as well as the length of the palatoquadrate became significantly shorter than the control group (p < 0.001), while there was no significant difference in the length and width of the mandible. The expression of Sox3, which was required in early embryonic craniofacial development, was significantly downregulated in the adamts2-knockdown zebrafish embryos. Bioinformatic and cellular studies showed that the decreased expression of ADAMTS2 may inhibit downstream ErbB signaling pathway transduction and restrain subsequent osteogenesis in human adult mesenchymal stromal cells. Collectively, these data showed that ADAMTS2 (c.3506G>T: p.G1169V) may confer susceptibility to risk of skeletal Class III malocclusion with maxillary deficiency.

Background: Tooth agenesis is a common dental anomaly that can substantially affect both the ability to chew and the esthetic appearance of patients. This study aims to identify possible genetic factors that underlie various forms of tooth agenesis and to investigate the possible molecular mechanisms through which human dental pulp stem cells may play a role in this condition. Results: Using whole-exome sequencing of a Han Chinese family with non-syndromic tooth agenesis, a rare mutation in FGFR1 (NM_001174063.2: c.103G > A, p.Gly35Arg) was identified as causative and confirmed by Sanger sequencing. Via GeneMatcher, another family with a known variant (NM_001174063.2: c.1859G > A, p.Arg620Gln) was identified and diagnosed with tooth agenesis and a rare genetic disorder with considerable intrafamilial variability. Fgfr1 is enriched in the ectoderm during early embryonic development of mice and showed sustained low expression during normal embryonic development of Xenopus laevis frogs. Functional studies of the highly conserved missense variant c.103G > A showed deleterious effects. FGFR1 (c.103G > A) was overexpressed compared to wildtype and promoted proliferation while inhibiting apoptosis in HEK293 and human dental pulp stem cells. Moreover, the c.103G > A variant was found to suppress the epithelial-mesenchymal transition. The variant could downregulate ID4 expression and deactivate the TGF-beta signaling pathway by promoting the expression of SMAD6 and SMAD7. Conclusion: Our research broadens the mutation spectrum associated with tooth agenesis and enhances understanding of the underlying disease mechanisms of this condition.

Genome-wide association studies have identified numerous loci associated with nonsyndromic cleft lip with/without cleft palate (nsCL/P). However, the causal genes within these loci remain to be systematically investigated. Through a multiomics screening strategy, we identified 20 candidate genes, with ARID3B emerging as the most significant risk gene for nsCL/P. Focusing on the ARID3B locus, we found a casual variant at rs1821848 that diminished the binding affinity of NR2C2, resulting in the upregulation of ARID3B. Notably, we observed the formation of ARID3B granules through liquid-liquid phase separation (LLPS) both in vivo and in vitro. This ARID3B-mediated LLPS could essentially recruit coactivators SMAD2/3 and establish enhancer activity necessary for initiating the gene profile related to nsCL/P. Ultimately, disrupting the LLPS of arid3b effectively rescued migration, apoptosis, and phenotype deficits in zebrafish models. This study systematically revealed biological functions of both rs1821848 and ARID3B during nsCL/P development.