NADPH oxidase deficiency causes impaired immunity which of the follwoing process?
**Core Concept**
NADPH oxidase is an enzyme complex that plays a crucial role in the respiratory burst of phagocytic cells, such as neutrophils and macrophages. This process involves the production of reactive oxygen species (ROS) to kill ingested microorganisms and eliminate pathogens. Impaired function of NADPH oxidase can lead to defective killing of microbes, resulting in recurrent infections.
**Why the Correct Answer is Right**
Chronic granulomatous disease (CGD) is a rare genetic disorder characterized by the inability of phagocytic cells to produce ROS due to NADPH oxidase deficiency. This deficiency leads to impaired killing of catalase-positive microbes, such as Staphylococcus aureus and Aspergillus species. As a result, patients with CGD develop recurrent life-threatening infections, particularly in the lungs, liver, and lymph nodes. **The NADPH oxidase complex consists of two membrane-bound subunits (gp91phox and p22phox) and three cytosolic subunits (p47phox, p67phox, and p40phox), which are essential for the production of ROS.**
**Why Each Wrong Option is Incorrect**
**Option A:** Chediak-Higashi syndrome is a rare genetic disorder characterized by albinism, recurrent infections, and bleeding tendency, due to mutations in the LYST gene. It is not directly related to NADPH oxidase deficiency.
**Option C:** Leucocyte adhesion defect type 1 (LAD1) is a rare immunodeficiency disorder caused by mutations in the ITGB2 gene, leading to impaired leukocyte adhesion to endothelial cells. It is not associated with NADPH oxidase deficiency.
**Option D:** Leucocyte adhesion defect type 2 (LAD2) is a rare immunodeficiency disorder caused by mutations in the FLNA gene, leading to impaired leukocyte adhesion to endothelial cells. It is not associated with NADPH oxidase deficiency.
**Clinical Pearl / High-Yield Fact**
Chronic granulomatous disease is a classic example of an immunodeficiency disorder caused by a defect in the respiratory burst of phagocytic cells. Patients with CGD require lifelong antibiotic prophylaxis and may benefit from granulocyte transfusions in severe infections.
**✓ Correct Answer: B. Chronic granulomatous disease**