Higher numbers of PTPN22 KO compared to WT CD4 T cells were recovered from lymph nodes and spleen, further confirming that the influence of PTPN22 on lymphopenia induced T cell proliferation was cell intrinsic and independent of the presence of other PTPN22 KO hematopoietic cells (Figure 4A). The gene discussed is PTPN22; the disease is lymphopenia.