UNC93B1 and Splenomegaly: Both hemizygous founder mice died before breeding (the female died at 8 wk, the male at 10 wk), but we were able to perform gross necropsy, which revealed extreme splenomegaly in both Unc93b1T93I/- mice relative to Unc93b1+/+, Unc93b1+/−, and Unc93b1−/− littermates (Fig. S5, B and C).