ESID criteria for CID diagnosis require that apart from severe infection or immune dysregulation or affected family members, two of the four following T-cell criteria must be met: (a) reduced CD3 or CD4 or CD8 T-cells, (b) reduced naïve CD4 and/or CD8 T-cells, (c) elevated TCRγδ+T-cells, (d) reduced proliferation to mitogen or TCR stimulation (51). This evidence concerns the gene CD4 and infection.