COL4A3 and hydrops fetalis: Remarkably, despite the reduction in EF% for females Col4a3-/- 129x1/SvJ (from 64.75 to 52.17) and Col4a3-/- C57Bl/6 (from 57.33 to 42.18%), values remained >40%, which represents an intermediate group for HF with preserved EF (HFpEF) [50].