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ABO blood group: The major human blood group system. The ABO type of a person depends on the presence or absence of two genes, A and B. These genes determine the configuration of the red blood cell surface. A person who has two A genes has red blood cells of type A. A person who has two B genes has red cells of type B. If the person has one A and one B gene, the red cells are type AB. If the person has neither the A nor the B gene, the red cells are type O. It is essential to match the ABO status of both donor and recipient in blood transfusions and organ transplants. MN Blood Group system in Humans The MN blood group system is under the control of an autosomal locus found on chromosome 4, with two alleles designated LM and LN. The bloodtype is due to a glycoprotein present on the surface of red blood cells, which behaves as a native antigen. Phenotypic expression at this locus is codominant because an individual may exhibit either one or both antigenic substances. Frequencies of the two alleles vary widely among human populations. The Rh blood group is one of the most complex blood groups known in humans. From its discovery 60 years ago where it was named (in error) after the Rhesus monkey, it has become second in importance only to the ABO blood group in the field of transfusion medicine. It has remained of primary importance in obstetrics, being the main cause of hemolytic disease of the newborn (HDN). The complexity of the Rh blood group antigens begins with the highly polymorphic genes that encode them. There are two genes, RHD and RHCE, that are closely linked. Numerous genetic rearrangements between them has produced hybrid Rh genes that encode a myriad of distinct Rh antigens. To date, 49 Rh antigens are known. The significance of the Rh blood group is related to the fact that the Rh antigens are highly immunogenic. In the case of the D antigen, individuals who do not produce the D antigen will produce anti-D if they encounter the D antigen on transfused RBCs (causing a hemolytic transfusion reaction, HTR) or on fetal RBCs (causing HDN). For this reason, the Rh status is routinely determined in blood donors, transfusion recipients, and in mothers-to-be. Despite the importance of the Rh antigens in blood transfusion and HDN, we can only speculate about the physiological function of the proteins, which may involve transporting ammonium across the RBC membrane and maintaining the integrity of the RBC membrane. #GeneticTesting #DNA #gene #genome #geneExpression #phenotype #chromosome #GeneticsExamQuestionsSolutions #geneticCode #GeneticExamQuestionsSolutions #eukaryotes #alleles #proteins #genotype #chromosomes #genes #GeneticsLecture #GeneStructure #MNBloodGroupSystem #RhBloodGroup #BloodTransfusionMedicalTreatment #antigens #glycoprotein #aboBloodGroup #bloodTyping #bloodTypingMadeEasy #bloodTypingLab #bloodTypingTest #bloodTypingExplained
