IL2RB and hyperinsulinemic hypoglycemia, familial, 4: Similar to ICOS deficiency, IL-2/IL-15Rβ deficiency does not cause decreases of stages 1 and 2 MAIT cells, suggesting that IL-2/IL-15R signal does not play an important role for early MAIT cell development, which is consistent with the lack of expression of this receptor in these MAIT cells.