CGB3 encodes the beta subunit of human chorionic gonadotropin (hCG), a glycoprotein essential for pregnancy maintenance. As part of the hCG heterodimer with the alpha subunit, CGB3 stimulates ovarian steroid synthesis critical for pregnancy support 1. The beta subunit confers receptor specificity and biological activity through G protein-coupled receptor signaling, activating the ERK1/2 pathway with kinetics similar to other beta variants 1. CGB3 expression is regulated by DNA methylation of its promoter region and TFAP2A transcription factor levels, with methylation inversely correlating with expression in both normal and pathological tissues 2. In pregnancy, SARS-CoV-2 infection is associated with decreased placental CGB3 expression alongside immune gene upregulation, suggesting potential long-term offspring effects 3. Clinically, CGB3 methylation status serves as a biomarker for cervical cancer detection, with high diagnostic sensitivity (AUC 0.83) in distinguishing abnormal from normal samples 4. In ovarian cancer, CGB3-9 genes show elevated expression linked to promoter demethylation and TFAP2A upregulation 5. Abnormal CGB expression also associates with uremia pathogenesis through immune dysregulation and apoptotic pathways 6, and co-expression of CGB1/CGB2 characterizes multiple cancer types 7.