The majority of HE cells in the major arteries (dorsal aorta, vitelline and umbilical) undergo EHT between E9.0-–10.5, resulting in the formation of Kit+ CD31+ Runx1+ hematopoietic cells that remain briefly attached as clusters to the luminal wall of the arteries. The gene discussed is RUNX1; the disease is hereditary elliptocytosis.