Differential Diagnosis
- Single most likely diagnosis
- G) X-linked agammaglobulinemia: This condition is characterized by the lack of B cells and consequently, very low levels of all immunoglobulins (IgA, IgG, IgM), which fits the patient's laboratory profile. The patient's history of recurrent severe infections, such as Streptococcus pneumoniae meningitis and bacteremia, also supports this diagnosis. The family history of maternal uncles dying from infections at a young age further points towards an X-linked condition.
- Other Likely diagnoses
- B) HIV infection: Although less likely given the specific pattern of immunoglobulin deficiency, HIV infection can lead to recurrent infections and alterations in immune cell counts. However, the specific pattern of very low IgG and IgM with a slightly elevated IgA does not typically align with HIV, where you might expect to see a more generalized immunosuppression.
- F) Transient hypogammaglobulinemia of infancy: This condition involves a temporary decrease in immunoglobulin levels during infancy. However, the severity and pattern of infections, along with the very low levels of IgG and IgM, make this less likely.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- D) Severe combined immunodeficiency (SCID): Although the patient has some T cell function (as evidenced by the presence of lymphocytes and a response to infection), SCID is a critical diagnosis not to miss due to its severe prognosis and the need for prompt intervention, such as bone marrow transplantation.
- Rare diagnoses
- A) Common variable immunodeficiency: Typically presents later in life and with a more variable immunoglobulin profile.
- C) Selective IgA deficiency: Characterized by low levels of IgA with normal levels of IgG and IgM, which does not fit this patient's profile.
- E) Thymic-parathyroid dysplasia (DiGeorge syndrome): Primarily involves T cell deficiency and abnormalities in calcium metabolism due to parathyroid dysfunction, not primarily a disorder of immunoglobulin levels.