A child presents with recurrent infections with bacteria, fungi, and viruses. The resident asks the attending physician about IL-2R gamma chain mutations, as the patient is a male. The attending physician makes a diagnosis and begins writing orders for bone marrow transplantation and possible gene therapy. Which of the following does the patient have?

Correct Answer: D

Rationale: SCID, often X-linked due to IL-2Rγ mutations, causes severe infections and requires bone marrow transplantation.

Correct Answer: D

Rationale: Edward Jenner used cowpox virus to vaccinate against smallpox, leveraging cross-immunity between the related viruses.

Correct Answer: C

Rationale: Bone marrow transplantation carries a high risk of GVHD due to the presence of immunocompetent donor T cells.

Correct Answer: C

Rationale: Somatic hypermutation occurs in B cells during their mitosis and differentiation in the bone marrow or lymphoid tissues, enhancing antibody affinity.

Correct Answer: A

Rationale: Chronic granulomatous disease results from defective NADPH oxidase, impairing macrophages' ability to kill catalase-producing bacteria.