Total T cell count normal, but severe reduction of naïve CD4+ T cells (CD4+CD45RA+ decreasing from 200 to 60/μl at 4-5 months of age; 1.86% TREC in CD3+CD45+) and rather increased CD8+ T cells (attributed to CMV infection), substantially increased proportion of TCRγδ+ T cells (>50% of CD3+; [normal <15%]), Normal B cells, Normal NK cells IgG and IgM increased, IgA normal, IgE increased (192–1,300 IU/mL) T cell proliferation upon PHA reduced, mildly reduced upon ConA, low-normal upon CD3/CD28. Here, PTPRC is linked to cytomegalovirus infection.