Which of the following diagnostic tests is commonly used to assess immune function in individuals suspected of having an immunodeficiency disorder?

Explanation: The correct answer is d. Immunoglobulin levels. Immunoglobulin levels, specifically IgG, IgM, and IgA, are commonly measured to assess immune function and identify deficiencies in immunoglobulin production. Abnormalities in immunoglobulin levels can indicate the presence of an immunodeficiency disorder.

Incorrect choices:

a. A complete blood count (CBC) provides information about various blood components, such as red blood cells, white blood cells, and platelets, but it does not specifically assess immune function.

b. A chest X-ray may be used to evaluate the condition of the lungs and detect infections, but it is not a specific test for immunodeficiency disorders.

c. Allergy skin testing is used to diagnose allergies and assess the body's response to allergens, but it is not a diagnostic test for immunodeficiency disorders.

Explanation: The correct answer is b. X-linked agammaglobulinemia. X-linked agammaglobulinemia is a primary immunodeficiency disorder caused by a genetic mutation that leads to the absence of mature B cells, resulting in an inability to produce antibodies (immunoglobulins). As a result, individuals with this disorder are highly susceptible to infections, especially bacterial infections.

Incorrect choices:

a. DiGeorge syndrome is a primary immunodeficiency disorder characterized by abnormalities in the development of certain organs, including the thymus, leading to impaired T cell function.

c. Severe combined immunodeficiency (SCID) is a group of rare genetic disorders that affect both T cells and B cells, resulting in a severe impairment of the immune system.

d. Acquired immunodeficiency syndrome (AIDS) is a secondary immunodeficiency disorder caused by the human immunodeficiency virus (HIV) infection, which specifically targets and destroys CD4+ T cells, weakening the immune system's ability to fight infections.