p BLOOD TYPE B IN Asiatic COUNTRIES The ABO pipeline ag chemical group arrangement is the main croup end for roue transfusion compatibilities . The presence of A , B , or AB antigens in the blood also determines the mastery of organ transplantations . These antigens generated by blood-group specific glycosyl communicateases , argon located on the scrape of blood cells . Approximately 14 years agone , molecular modifications in the sequence of the ABO venue were determine resulting in phenotypic variations in the classical ABO blood group system . Further investigations resulted in eight blood typeface A variants and six blood type B variants (Olsson et al , 2001 . These variants harbored missense mutations in specific exons that generate alterations in the loot bowed stringed instrument of the ABO antigens . Suc h reports have significantly dissembleed serologic protocols that were closely associated with donor-patient compatibility testings , because these variants had the capacity to express the antigens at a broader hold of degree of expression than what was classically described . This quandary may cause mistyping of blood groups which , in turn , may affect transfusion and transplantation proceduresThe ABO blood group system has been determined to follow a unique geographic diffusion (Fukumori et al , 1996 . Frequencies of individuals with blood type B ar know to be peculiar(prenominal)(prenominal)ly eminent-pitched in Asian countries , ranging up to 30 is specific populations such as the Himalayans . The Himalayan region has been reported to have a history of smallpox and bubonic plague epidemics , which ar specific medical illnesses that confer particular physiological responses in the body that blood types A and O are selected against (Yamamoto et al , 1993 Suc h selection is also associated with the or! ganic evolution of resistance to the other antigens , thereof blood type B is said to be fixed in the area finished the mechanism of genic driftInvestigations on the ABO venue has revealed that miry sequence variations occur within this region , resulting in substitutions of nucleotides bases that are presumably less susceptible to selection pressure , and then it is possible to trace the phylogeny of the B alleles in a more robust way . The diversification of the B locus may be a result of two patrimonial mechanisms . Point mutations may have occurred in the consensus ABO locus due to recombination events (Olsson and Chester 1995 . The fixation rates of a mutation may be calculated based on its extent of homology to the consensus B locus . This may be observed in the high frequencies in Asian populations and the low frequencies in different sportsmanlike populations . Recombination facilitates the generation of new variants of blood type B may also be enhanced by in ter-lineage sequence designate , resulting in intermediate products of the B alleleBlood type B is strongly associated with specific medical diseases such as esophageal carcinoma , infantile diarrhea and typhoid fever (Su et al , 2001 . These associations may be due to the selection against the other blood types during the onset of the medical illness . In addition the B antigen is maximally naming(prenominal) in these populations because the physiological settings of these individuals are optimal for the fixation...If you want to escape from a full essay, order it on our website: OrderCustomPaper.com
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