However, given that they reflect different hereditary factors (i.e., genetic only or both genetic and environmental), it is likely that an interaction of the effects of FH and APOE4 exists for AD-related brain changes such that having both FH and APOE4 will lead to synergistic influences on AD-related brain changes compared to when an individual has only one of the two risk factors. The gene discussed is APOE; the disease is Alzheimer disease.