PSG8 (pregnancy-specific beta-1-glycoprotein 8) is a member of the PSG gene family located on chromosome 19.2, part of the carcinoembryonic antigen (CEA) superfamily 1. PSG8 is primarily synthesized by placental syncytiotrophoblasts and belongs to the immunoglobulin superfamily, characterized by an N-terminal immunoglobulin variable domain 2. The gene is regulated epigenetically through CTCF-mediated mechanisms, with CTCF depletion upregulating PSG8 transcription and altering histone modifications at its promoter 3. Beyond pregnancy, PSG8 expression has significant cancer associations. It is upregulated in hepatocellular carcinoma cells with high lymphatic metastatic potential 4, and its expression correlates with poor prognosis specifically in female lung adenocarcinoma patients, particularly when combined with PSG3 and PSG7 5. A long non-coding RNA ortholog, PSG8-AS1, shows oligodendrocyte-specific expression and peaks during human myelination, suggesting developmental roles beyond pregnancy 6. Additionally, PSG8 plasma levels serve as a biomarker for distinguishing ectopic pregnancy from normal intrauterine pregnancy 7. The specific biological function(s) of PSG8 remain incompletely characterized.