In contrast to mice transplanted with HSCs expressing IL-17 which died within 14 days after transplantation, those with reconstituted bone marrow hematopoiesis survived without any autoimmune disorders during the observational period of over 16 weeks even though they had an increased number of Th17 cells showing intracellular expression of IL-17. The gene discussed is IL17A; the disease is Autoimmunity.