Helen Sant , 3, does her school work with older siblings, Caesar, 9 (left), and Maria-Anita, 7, at their home Tuesday, January 29, 2018. Both Caesar and Maria-Anita have sickle cell disease. In vitro fertilization allowed Helen to be born free of sickle cell anemia. They had selected an embryo that was an exact bone marrow match for Caesar. At the time of Helen's birth doctors took a donation of umbilical cord blood that could one day be used in a bone marrow transplant for Caesar.