Ptpn2ex2−/ex2− mice had defects in erythropoiesis and B cell development as evident in Ptpn2−/− (BALB/c) mice, but not splenomegaly and did not exhibit an accumulation of myeloid cells in the spleen as seen in Ptpn2−/− (BALB/c) mice. Here, PTPN2 is linked to Splenomegaly.