CD59 defect is seen as marker of which disease
Correct Answer: Paroxysmal Nocturnal Hemoglobinuria
Description: (A) Paroxysmal Nocturnal Hemoglobinuria (PNH)[?]PAROXYSMAL NOCTURNAL HEMOGLOBINURIA (PNH) is a disease, due to acquired mutations in Phosphatidyl Inositol Glycan Complementation Group gene (PIGA)..oAssociated with deficiency of glycosylphosphatidylinositol (GPI) anchor proteins along with absence of external surface membrane proteins attaching to it.oCD55 (DAF) and CD59 (MIRL) are two such complement defence proteinsoCD59 deficiency:oCommon finding in RBCs & WBCs of patients with chronic hemolysis suffering from PNHoDiagnosis: Based on demonstration of a substantial proportion of patient's RBC having increased susceptibility to complement (C), due to the deficiency on their surface of proteins (particularly CD59 & CD55)[?]Pathogenesis of CD55 & CD59:oInherited absences of both proteins in humans have been described:-Most inherited deficiencies of CD55 - no district clinical hemolytic syndrome-Inherited absence of CD59 - produces a clinical disease similar to PNH with hemolysis & recurrent thrombotic events[?]Paroxysmal nocturnal hemoglobinuria (PNH):oCD59 inhibit C9 bind to C5b, 6,7,8oDecay-accelerating factor (DAF) displace Bb from C3b and C2b from C4boBoth CD59 & DAF are defect in PNHSTAGES AT WHICH COMPLEMENT ACTIVITY IS REGULATEDC1q binding to antigen: antibody complexes activates C1r and C1sC1 inhibitor (C1INH) dissociates C1r and C1s from the active C1 complex.C4b,2b is the active C3 convertase cleaving C3 to C3a and C3bDAF, C4BP and CR1 displace C2b from the C4b, 2b complex. C4b bound by C4BP, MCP, or CR1 is cleaved by a soluble prolease I to inactive forms C4d and C4c.The C5 convertases cleave C5 to C5a and C5b.CR1 and H displace C3b. CR1 and H act as cofactors in the cleavage of C3b by I.The terminal components of complement form a membrane pore - the membrane attack complex.CD59 prevents final assembly of the membrane attack complex at the C8 to C9 stage.Other Options[?]PTEN (phosphatase and tensin homologue)-Is a membrane-associated phosphatase encoded by a gene on chromosome 10q23 that is mutated in Cowden syndrome, an autosomal dominant disorder marked by frequent benign growths, such as skin appendage tumors, and an increased incidence of epithelial cancers, particularly of the breast, endometrium, and thyroid.[?]Hereditary spherocytosis (HS):-Is an inherited disorder caused by intrinsic defects in the red cell membrane skeleton that render red cells spheroid, less deformable & vulnerable to splenic sequestration and destruction.-The prevalence of HS is highest in northern Europe, where rates of 1 in 5000 are reported.[?]Cowden syndrome:-Dysplastic gangliogliocytoma of the cerebellum (Lher- mitte-Duclos disease), caused by mutations in PTEN resulting in PI3K/AKT signaling pathway activity.
Category:
Pathology
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