What is an example of a congenital humoral (B-cell) immunodeficiency?

• A. Severe combined immunodeficiency syndrome
• B. X-linked hypogammaglobulinemia
• C. DiGeorge's Syndrome
• D. HIV infection

Answer: (B)

The selection of X-linked hypogammaglobulinemia as an example of a congenital humoral (B-cell) immunodeficiency is appropriate because this disorder is specifically characterized by a deficiency in antibody production due to B-cell dysfunction. In X-linked hypogammaglobulinemia, there is a mutation in the BTK gene, which is crucial for B-cell development and signaling. As a result, individuals with this condition have low levels of immunoglobulins (antibodies) and experience a higher susceptibility to infections.

This particular immunodeficiency is inherited in an X-linked recessive manner, predominantly affecting males, leading to symptoms associated with inadequate humoral immunity. The focus on B-cell dysfunction distinguishes it in the context of congenital immunodeficiencies, making it a clear example within this category.

In contrast, other conditions mentioned involve different mechanisms or combinations of immune deficiencies. Severe combined immunodeficiency syndrome, for instance, affects both T-cells and B-cells, indicating that it's not purely a humoral deficiency. DiGeorge's syndrome primarily involves T-cell deficiencies due to thymic aplasia, while HIV infection is an acquired immunodeficiency that affects various components of the immune system, especially T-cells