APOE and hydrops fetalis: ApoE−/− + HF mice can absorb excess exogenous cholesterol into the blood circulation through the intestine for a long time, and then transport it to the peripheral tissues for utilization, while the excess exogenous cholesterol that cannot be used in time will be temporarily stored in cells, which will lead to a sharp increase in the cholesterol content of peripheral tissues, so more HDL is needed to transport exogenous cholesterol.