Abstract
Tooth agenesis (TA), the congenital absence of one or more teeth, is the most common manifestation of defective dental morphogenesis in humans. TA can occur as an isolated (non-syndromic) condition or as part of a broader syndromic presentation. In this review, we analyzed a total of 73 manuscripts to provide a comprehensive update on the genetic landscape of TA. To investigate the genes, variants, and associated phenotypes, we reviewed data from curated databases including Human Phenotype Ontology (HPO), OMIM, ClinVar and MalaCards. Based on the current evidence, the genes most frequently implicated in TA are MSX1, EDA, and PAX9. However, chromosomal abnormalities, such as those seen in Down syndrome and Williams syndrome, along with structural variations (e.g., deletions and duplications), also contribute significantly to TA etiology. The most involved pathways include TNF receptor binding, encompassing genes such as EDA, EDA2R, EDAR, and EDARADD, and the mTOR signaling pathway, which includes AXIN2, FGFR1, LRP6, WNT10A, and WNT10B. The aim of this review is to provide an critical synthesis of the genetic mechanisms underlying TA, highlighting the contribution of major signaling pathways, regulatory networks, and emerging molecular insights that may inform diagnostic and therapeutic advances.