This review paper, conducted between January and March 2025 and based on a comprehensive analysis of previous studies, investigates the function of members of the PAX gene family in human illnesses. PAX genes serve as critical regulators in the development of various tissues and organs, and mutations in these genes have been linked to a broad spectrum of genetic disorders and cancers. The research focused on the functions of individual PAX genes and their associations with disease phenotypes. For instance, mutations in PAX9 are linked to tooth agenesis, with the severity of dental anomalies depending on the mutation’s impact on DNA-binding capacity. Mutations in PAX2 have been associated with renal and ocular malformations, notably papillorenal syndrome, characterized by renal hypoplasia and optic nerve defects. Additionally, PAX4 and PAX6 are essential for the differentiation of pancreatic endocrine cells, and their mutations are implicated in various forms of diabetes. Moreover, aberrant expression of PAX genes is observed in several cancer types. PAX3 and PAX7 expression correlates with melanoma and sarcoma progression, while PAX2 and PAX8 are frequently expressed in Wilms tumor, a pediatric kidney cancer. These genes can influence tumor initiation, progression, or resistance mechanisms, though their exact oncogenic roles remain to be fully defined. The findings highlight the necessity for detailed characterization of PAX gene isoforms, mutation effects, and tissue-specific functions. Future investigations should also address the roles of PAX genes in adult tissue regeneration and further elucidate their contributions to developmental disorders and cancer biology.