APOE-ε4 has been linked with about 65-75% of sporadic Alzheimer’s disease, but such association is also described for up to 20% of other types of dementia [19]; on the other hand, the link between APOE-ε4 and HF is not strictly consistent, depending firstly on the severity of cardiac disease or the selected population study (low or high risk subjects) [20, 21]. The gene discussed is APOE; the disease is hydrops fetalis.