In Bruton's agammaglobulinemia, what is the characteristic concentration of immunoglobulins?

Bruton's agammaglobulinemia, also known as X-linked agammaglobulinemia, is characterized by a significant reduction or complete absence of all types of immunoglobulins (IgG, IgA, IgM, and other subclasses). This condition results from a mutation in the Bruton's tyrosine kinase (BTK) gene, which plays a critical role in B-cell development and maturation. As a result, individuals with this disorder have very few B cells or none at all, leading to a failure in antibody production.

The hallmark of Bruton's agammaglobulinemia is indeed the decreased to absent immmunoglobulin concentrations. Clinically, patients with this condition are highly susceptible to infections, particularly from encapsulated bacteria, due to their compromised immune response. The diagnosis can be confirmed through serological testing, which would typically reveal undetectable levels of immunoglobulins, thereby affirming the correct answer.