Like FasC194VTg lpr/lpr mice, FasC194VKI/KI mice do not display lymphadenopathy, splenomegaly, accumulation of CD4−CD8− peripheral T cells, or autoantibody formation, all of which are hallmarks of Fas deficiency (Supplemental Figure S1). Here, FAS is linked to hyperinsulinemic hypoglycemia, familial, 4.