////////////////Lymphopenia is the classic hallmark of severe combined immunodeficiency (SCID); however, normal or even elevated lymphocyte counts can be seen in a significant proportion of patients. Failure to make the diagnosis because the child is not frankly lymphopenic may present a problem, particularly in patients with Omenn syndrome, bare lymphocyte syndrome, and interleukin (IL)–2 deficiency. Obtaining lymphocyte markers and test results of antibody and lymphocyte proliferation can help physicians to avoid this pitfall.
