Bases moleculares do sistema Rh e suas aplicações em obstetrícia e medicina transfusional

Abstract

The Rh system is the most polymorphic and immunogenic of all blood group systems. Currently, over 49 antigens have been identified, among which the five main antigens are D, C, c, E, e. Knowledge of the Rh system's molecular basis, since its first cloning 17 years ago, has allowed for an understanding of the mechanism of Rh-negative phenotype and of the variants of antigens RHD and RHCE. Deletions, gene rearrangements and insertions are the main mutations. In Caucasians, the primary mechanism of Rh-negative phenotype is the complete RHD gene deletion, whereas in Afrodescendant it is the presence of pseudogene RHDø and hybrid gene RHD-CE (4-7)-D. The authors analyzed the structure of the Rh complex in red cells, the molecular basis of the Rh system, mechanisms of RHD negativity and weak and partial RHD expressions.

Sistemas Sanguíneos, Incompatibilidade E Procedimentos Alternativos À Transfusão / Blood Systems, Incompatibility of Alternative Procedures to Transfusion

“…É formado por diversas proteínas, sendo a D de maior importância. A presença desta na superfície das hemácias caracteriza o fenótipo como Rh positivo, e Rh negativo quando ausente (CAIXETA;SILVA, 2019;NARDOZZA et al, 2010).…”

Male individuals with Robin Sequence: emerging significant association with ABO and RhD blood group phenotypes

“… 1 , 2 , [4] , 5 , 6 The RHD and RHCE genes, located on the short arm of chromosome 1, encode Rh antigens. 3 , [4] , 5 , 7 …”

Impact on patient of the detection of weakly expressed RhD antigens in blood donors

“… 9 Amino acid substitution in the intracellular or transmembrane segment of the RhD protein leads to weakening of the D antigen expression in the membrane of red blood cells resulting in a weak D phenotype. 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 Hence, weak D testing must always be performed in blood donors with absent reactivity in the screening test, and if the results are weakly positive, the donors must be classified as RhD-positive in order to prevent anti-D alloimmunization in RhD-negative patients who receive transfusions of packed red blood cells. 6 , 7 , 8 , 10 …”