The reasons are not clear and could vary across countries, but in Georgia, where the anti-HBc prevalence plateaued after 35 years of age but HBsAg prevalence declined, the likely explanation would be deaths of HBsAg-positive persons from HBV-related (cirrhosis, liver cancer) or other causes (e.g. high-risk behaviours, such as injectable drug use) resulting in lower HBsAg prevalence in the elderly. The gene discussed is KRT88P; the disease is liver cancer.