TAILIEUCHUNG - Chapter 061. Disorders of Granulocytes and Monocytes (Part 9) Chronic Granulomatous Disease Chronic

Chronic Granulomatous Disease Chronic granulomatous disease (CGD) is a group of disorders of granulocyte and monocyte oxidative metabolism. Although CGD is rare, with an incidence of 1 in 200,000 individuals, it is an important model of defective neutrophil oxidative metabolism. Most often CGD is inherited as an X-linked recessive trait; 30% of patients inherit the disease in an autosomal recessive pattern. Mutations in the genes for the four proteins that assemble at the plasma membrane account for all patients with CGD. Two proteins (a 91-kDa protein, abnormal in X-linked CGD, and a 22-kDa protein, absent in one form of. | Chapter 061. Disorders of Granulocytes and Monocytes Part 9 Chronic Granulomatous Disease Chronic granulomatous disease CGD is a group of disorders of granulocyte and monocyte oxidative metabolism. Although CGD is rare with an incidence of 1 in 200 000 individuals it is an important model of defective neutrophil oxidative metabolism. Most often CGD is inherited as an X-linked recessive trait 30 of patients inherit the disease in an autosomal recessive pattern. Mutations in the genes for the four proteins that assemble at the plasma membrane account for all patients with CGD. Two proteins a 91-kDa protein abnormal in X-linked CGD and a 22-kDa protein absent in one form of autosomal recessive CGD form the heterodimer cytochrome b-558 in the plasma membrane. Two other proteins 47 and 67 kDa abnormal in the other autosomal recessive forms of CGD are cytoplasmic in origin and interact with the cytochrome after cell activation to form NADPH oxidase required for hydrogen peroxide production. Leukocytes from patients with CGD have severely diminished hydrogen peroxide production. The genes involved in each of the defects have been cloned and sequenced and the chromosome locations identified. Patients with CGD characteristically have increased numbers of infections due to catalase-positive microorganisms organisms that destroy their own hydrogen peroxide . When patients with CGD become infected they often have extensive inflammatory reactions and lymph node suppuration is common despite the administration of appropriate antibiotics. Aphthous ulcers and chronic inflammation of the nares are often present. Granulomas are frequent and can obstruct the gastrointestinal or genitourinary tracts. The excessive inflammation probably reflects failure to inhibit the synthesis or degradation of chemoattractants and antigens leading to persistent neutrophil accumulation. Impaired killing of intracellular microorganisms by macrophages may lead to persistent cell-mediated immune .

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