SBB Genetic, Rh and RBC membrane - Exam Questions amd Answers Latest 2024/2025 (Graded)

SBB Genetic, Rh and RBC membrane - Exam Questions amd Answers Latest 2024/2025 (Graded) what is Rh-associated glycoprotein. (RhAG)? - answersErythrocytes express a third Rh-protein termed shares 38% identity with RhD/RhCE, has the same topology in the membrane, and is encoded by a single gene on chromosome 6. what are the RHAG blood group system antigens ? - answers1- Duclos is RHAG1, 2- Ol(a) is RHAG2, 3- DSLK is provisionally RHAG3. There are Several other proteins associate with RhAG;what are they? - answers1- CD47, or 2- integrin associated protein (IAP); 3- LW (ICAM-4); 4- glycophorin B. 5- Band 3 may also be associated with the complex Page 2 of 26 Rh null Phenotypes:"amorph"mutations - answersLess often, Rh null individuals have RHCE mutations,along with the common deletion of RHD,but Inherit RHAG what happen to the cell that Red cells lacking all Rh antigens(Rh null)? - answers1-red cells are stomatocytic and associated with mild anemia(a compensated hemolytic anemia), suggesting that the Rh proteins have an important structural role in the erythrocyte membrane. 2- increased osmotic fragility. Rh null Phenotypes due to "regulator" mutations - answers1- uncommon, the phenotype most often results from mutations in RHAG indicating that RhAG protein plays a critical role in trafficking RhCE and RhD to the membrane. 2- resulting absence of core Rh protein necessary for expression of Rh antigens. 3- Do inherit Rh genes but cannot express product. Page 3 of 26 what is the Rh-core complex? - answers1- RhAG associates with the Rh blood group proteins in the membrane to form an Rh-core complex. 2- The Rh complex is linked to the membrane skeleton through CD47-protein 4.2 interactions and through Rh/RhAG ankryin interactions. what is the relationship between the LW and Rh blood group system ? - answersthe LW antigen is present on Rh-positive red cells in greater amounts than on Rh-negative red cells. 2-Rh null cells are also LW(a-b-),These individuals produce anti-LWab. **LW antigens weak or absent from RBC that stored in EDTA and they sensitive to the DTT. what are the Rh terminology? - answers1- Fisher-Race in England was based on the premise that three closely linked genes, C/c, E/e, and D, were responsible, 2- Wiener nomenclature (Rh-Hr) Page 4 of 26 was based on the belief that a single gene encoded several blood group factors. **Neither theory was correct. 3- There are actually two genes, RHD and RHCE, as correctly proposed by Tippett. why Knowledge of paternal RHD zygosity is important in prenatal practice? - answersto predict the antigen status of the fetus to assess the risk of HDFN when the mother has antiD. why red cells from a DcE/DcE (R2R2) individual carry more D antigen sites and show higher titration scores with anti-D than red cells from a DCe/DCe (R1R1) individual? - answersbecause less D is expressed in the presence of C. As measured by flow cytometry,in which order D antigen strength decreases? - answersDcE/DcE (R2R2) DCe/DcE (R1R2) DCe/DCe (R1R1) DcE/ce (R2r) DCe/ce (R1r). WEAK D (FORMERLY DU) - answersWeak D red cells have historically been defined as having a reduced amount of D antigen, requiring an indirect antiglobulin test (IAT) for detection. Page 5 of 26 WEAK D DUE TO C - answersA weak D phenotype can occur when Ce (r′ ) is present in trans to RHD (eg, R0r′ ). Del - answersDel red cells express extremely low levels of D antigen that cannot be detected by routine serologic methods. However, these red cells can adsorb and subsequently elute anti-D. **Del will usually be detected only by RHD genotyping. PARTIAL D - answersthe red cells type as D positive, but individuals make anti-D when exposed to conventional D antigen. partial D phenotypes result due to? - answers1) missing portions of D. 2) the majority are due to hybrid genes resulting from regions of RhD joined to RhCE not only can result in the loss of D epitopes but also can generate new antigens. For example, DVI red cells carry the BARC antigen. Page 6 of 26 ELEVATED D - answers1- Several rare deletion phenotypes, designated D--, Dc-, and DCw-, have an enhanced expression of D antigen and no, weak, or altered C/c and E/e antigens. 2- These are the converse of partial D and result from replacement of portions of RHCE by RHD. 3- People with CE-depleted phenotypes often make anti-Rh17 (ani-Hr0) and Hr