To quantify HE, the Ncx1−/− line was crossed with the 23GFP transgenic reporter mouse line in which the Runx1 +23 enhancer mediates expression of a GFP reporter to all cells undergoing EHT, including pre-HE and HE (Bee et al., 2010; Swiers et al., 2013). This evidence concerns the gene SLC8A1 and hereditary elliptocytosis.