LRP2 and holoprosencephaly: Both Lrp1 and Lrp2 single knockout mice have severe developmental phenotypes. Lrp1 knockout blastocysts fail to implant and therefore do not develop into embryos [69]. Lrp2 knockout mice are mostly embryonic lethal, presenting with defects including a cleft palate, failure to form an olfactory bulb, and fusion of the forebrain hemispheres, resulting in a single ventricle (holoprosencephaly) [70].