What is an example of a congenital combined B and T cell immunodeficiency?

• A. X-linked hypogammaglobulinemia
• B. DiGeorge's Syndrome
• C. Severe combined immunodeficiency syndrome (SCIDS)
• D. AIDS

Answer: (C)

Severe combined immunodeficiency syndrome (SCIDS) is an example of a congenital combined B and T cell immunodeficiency. This condition is characterized by a significant impairment of both the humoral immune response (mediated by B cells) and the cell-mediated immune response (mediated by T cells). Individuals with SCIDS have a severely reduced ability to fight infections due to the lack of functional lymphocytes, leading to increased susceptibility to a wide range of pathogens.

SCIDS can arise from various genetic mutations affecting immune cell development or function, and this dual deficiency is what distinguishes it as a combined immunodeficiency. Patients often present early in life with recurrent infections and require prompt medical intervention, including potential stem cell transplantation, to re-establish their immune functions.

In contrast, other options refer to different types of immunodeficiencies or syndromes. X-linked hypogammaglobulinemia primarily involves impaired B cell function but does not affect T cells, making it not a combined immunodeficiency. DiGeorge's syndrome affects T cell development but can also lead to variable effects on B cells due to the thymus's role in T cell maturation. AIDS, caused by the HIV virus, leads to a progressive loss of T cells,