LRP6 and spina bifida: Another prominent phenotype in mice carrying either gain-of-function or loss-of-function mutations of Lrp6 is neural tube defects (NTDs) with full penetrance of spina bifida and incomplete penetrance of anterior neural tube closure defects causing exencephaly (Pinson et al., 2000; Carter et al., 2005; Bryja et al., 2009; Gray et al., 2010; Gray et al., 2013; Zhou et al., 2010; Zhao et al., 2022).