6
Diagnosis
Key Points
Î Primary immunodeficiency diseases (PIDDs) are inherited disorders
of immune system function that predispose affected subjects to an
increased rate and severity of infection, immune dysregulation with
autoimmune disease and aberrant inflammatory responses, and
malignancy.
Î Primary immunodeficiencies are distinct from secondary
immunodeficiencies that occur, for example, during certain viral
infections, after immunosuppression to prevent graft rejection after
transplantation, during treatment of systemic autoimmune disease,
and in association with cancer chemotherapy.
Î Primary immunodeficiencies occur in as many as 1:2000 live births.
Î The principal clinical manifestation of immunodeficiency is increased
susceptibility to infection.
Î Autoimmune disease and malignancy are also often seen in a variety of
immunodeficiencies.
Î In the course of evaluating immunodeficiency, it is critical, as much as
possible, to document carefully the foci of infections, the organisms,
and the response to treatment.
Î This is necessary to distinguish infectious disease from other
noninfectious conditions, such as allergy, or to distinguish viral
infection from bacterial infection.
Î Any other conditions that might predispose to infection, including
anatomic defects, allergy, and metabolic disorders, should be
considered where appropriate.
Î However, also note that hypersensitivity to environmental allergens,
food allergens, or both might be an important element of and
diagnostic clue for a variety of PIDDs.
