ZNF621 is a zinc finger transcription factor localized to nuclear specks with DNA-binding activity specific to RNA polymerase II cis-regulatory regions 1. It functions as a transcriptional regulator involved in RNA polymerase II-mediated transcription [GO annotations]. In nasopharyngeal carcinoma, ZNF621 is positively regulated by the long non-coding RNA LINC01140 through a competing endogenous RNA mechanism involving miR-452-5p, and enhances radiosensitivity of cancer cells 1. ZNF621 functions as a PPAR-responsive gene that can be transcriptionally activated by fatty acids, particularly through PPARγ agonism in breast cancer cells 2. Additionally, ZNF621 is associated with bone mineral density as a candidate causal variant (>90% probability) for both femoral neck and lumbar spine BMD 3. The gene exhibits differential DNA methylation patterns in high-altitude polycythemia patients, ranking among the top five genes with largest methylation differences in Tibetan populations 4, and shows sensitivity to gaseous air pollutant-induced epigenetic modifications 5. ZNF621 has been identified in fusion gene formations in benign smooth-muscle tumors 6, suggesting broader roles in cellular regulation beyond transcriptional control.