A Variant in the IRF6 Promoter Associated with the Risk for Orofacial Clefting

Exploring the genetics, mechanisms, and therapeutic innovations in non-syndromic tooth agenesis

Tooth agenesis is the congenital absence of one or more teeth in the normal series due to failures during dental development in the odontogenesis process. Although tooth development mechanisms are more precise in the literature, the etiology of non-syndromic tooth agenesis remains partially unknown. Mutations in genes that regulate the transcription factors involved in tooth development are associated with this condition. Despite advances in genetic research, questions remain about whose understanding might enable more precise and customized treatments. This study aimed to explain the molecular mechanisms associated with non-syndromic tooth agenesis and treatment progression regarding the condition in genetics. The search was non-systematic and performed in MedLine (via PubMed). The inclusion criteria were observational and experimental studies published in English, Portuguese, and Spanish, with open access and without time restrictions. The data analysis was narrative/descriptive. Fifty-three articles were selected. The primary genes associated with non-syndromic tooth agenesis identified in the study include PAX9 and MSX1 - essential for molar and premolar formation; WNT10A and WNT10B - involved in cell signaling during odontogenesis; AXIN2 - related to the regulation of cell control and colorectal cancer risk; EDA and EDAR - crucial for ectodermal structures; and BMP4 - regulates cell differentiation and morphogenesis. These lesions directly affect tooth formation and quantity. Understanding these genetic foundations and the molecular mechanisms of tooth agenesis is essential to improve diagnosis, develop customized therapies, and enhance patients' quality of life. Continuous research is critical to establish genetic-based therapeutic innovations.

Maternal factors increase risk of orofacial cleft: a meta-analysis

Orofacial clefts are among the most prevalent birth defects, with severe medical and psychosocial consequences. Cleft lip with or without cleft palate (CL ± P) and cleft palate only (CPO) affect on average nearly 1/700 births worldwide. The cause of most non-syndromic cases is unknown. Maternal factors and disorders are assumed to modify the risk of orofacial clefting. In the present study, we performed a systematic review and meta-analysis to analyze the effects of maternal underweight, obesity, hypertension, diabetes, as well as smoking, and alcohol consumption on the development of orofacial clefts. As CL ± CP and CPO have distinct pathogenetic backgrounds, these cleft subtypes were assessed separately. Altogether, 5,830 studies were identified and 64 of them met the inclusion and exclusion criteria. Obesity significantly elevated the odds of clefting (OR = 1.28, CI:1.08-1.51) (ORCL±CP = 1.23, CI:1.01-1.50; ORCPO = 1.31, CI:0.97-1.77). Maternal underweight also significantly increased the odds of clefting (OR = 1.21 CI:1.06-1.38). In mothers with type 1 diabetes, the odds of cleft development were significantly elevated (OR = 1,75, CI:1.45-2.12). Essential hypertension was also associated with higher odds of developing cleft (OR = 1.55, CI:1.18-2.03). Smoking during pregnancy significantly elevated the odds of cleft development (OR = 1.55, CI:1.34-1.79) (ORCL±CP = 1.58, CI:1.36-1.83; ORCPO = 1.50, CI:1.15-1.96). Passive smoking was even more damaging than active tobacco use, but alcohol consumption had no effect. In conclusion, this study clearly showed the importance of maintaining normal maternal body weight and emphasized the importance of hypertension and type 1 diabetes care in the first months of pregnancy. It also highlighted similarnegative effects of passive and active smoking, while alcohol consumption did not seem to be a significant risk factor for cleft development. However, there is a complete lack of available studies on the interactions of these factors, which is an essential direction for improving prevention.

Genetic association and functional validation of ZFP36L2 in non-syndromic orofacial cleft subtypes

BACKGROUND

Non-syndromic orofacial cleft (NSOC) is one of the most common craniofacial malformations with complex etiology. This study aimed to explore the role of specific SNPs in ZFP36L2 and its functional relevance in zebrafish models.

METHODS

We analyzed genetic data of the Chinese Han population from two previous GWAS, comprising of 2512 cases and 2255 controls. Based on the Hardy-Weinberg Equilibrium (HWE) and minor allele frequency (MAF), SNPs in the ZFP36L2 were selected for association analysis. In addition, zebrafish models were used to clarify the in-situ expression pattern of zfp36l2 and the impact of its Morpholino-induced knockdown.

RESULTS

Via association analysis, rs7933 in ZFP36L2 was significantly associated with various non-syndromic cleft lip-only subtypes, potentially conferring a protective effect. Zebrafish embryos showed elevated expression of zfp36l2 in the craniofacial region during critical stages of oral cavity formation. Furthermore, Morpholino-induced knockdown of zfp36l2 led to craniofacial abnormalities, including cleft lip, which was partially rescued by the addition of zfp36l2 mRNA.

CONCLUSION

Our findings highlight the significance of ZFP36L2 in the etiology of NSOC, supported by both human genetic association data and functional studies in zebrafish. These results pave the way for further exploration of targeted interventions for craniofacial malformations.