Which of the following statements is true regarding immunodeficiency disorders?

Explanation: The correct answer is b. Persistent fever and night sweats. Fever and night sweats are common clinical manifestations of immunodeficiency disorders. The immune system's inability to fight off infections can lead to recurrent fevers and night sweats as the body tries to combat pathogens.

Incorrect choices:

a. Hyperactivity and restlessness are not typical clinical manifestations of immunodeficiency disorders. These symptoms are more commonly associated with conditions affecting the central nervous system.

c. Weight gain and increased appetite are not typical clinical manifestations of immunodeficiency disorders. They may be seen in conditions like hypothyroidism or hormonal imbalances.

d. Elevated blood pressure is not a common clinical manifestation of immunodeficiency disorders. It may be seen in conditions like hypertension or cardiovascular disorders.

Explanation: The correct answer is d. Selective IgA deficiency. This disorder is characterized by a lack of immunoglobulin A, which can lead to an increased susceptibility to infections, particularly in the respiratory and gastrointestinal tracts.

Incorrect choices:

a. Selective IgM deficiency is a rare immunodeficiency disorder characterized by a lack of immunoglobulin M (IgM), not IgA.

b. X-linked agammaglobulinemia is a primary immunodeficiency disorder caused by a mutation in the BTK gene, resulting in a deficiency of B cells and immunoglobulins.

c. Common variable immunodeficiency (CVID) is a heterogeneous group of disorders characterized by decreased levels of immunoglobulins, including IgA, IgG, and IgM.