H4C2 (H4 clustered histone 2) is a histone-encoding gene located on chromosome 6. As a member of the histone H4 family, H4C2 is involved in nucleosome positioning and chr6 organization 1. The gene has been identified as a differentially expressed gene in pancreatic cancer, where it appears among the top 20 DEGs capable of distinguishing pancreatic cancer tissue from normal tissue 1. Additionally, H4C2 has been implicated in prostate cancer prognosis; it was identified as one of three exosome-related genes significantly associated with prostate cancer prognosis when analyzed through LASSO regression and multivariate Cox regression analysis 2. The H4C2 5' untranslated region (5'UTR) sequence has demonstrated functional utility in mRNA vaccine development, showing higher translation efficiency of mRNA-encoded antigens compared to sequences used in clinical mRNA vaccines 3. These findings suggest H4C2 has potential as a biomarker for cancer prognosis and as a regulatory element for improving mRNA vaccine efficacy. However, H4C2's primary molecular function beyond its role as a histone component requires further investigation.