p BLOOD TYPE B IN Asian COUNTRIES The ABO downslope ag convocation arrangement is the main stern end for neckcloth transfusion compatibilities . The presence of A , B , or AB antigens in the blood also determines the achievement 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 locus were identify 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 sugar bowed stringed instrument of the ABO antigens . S uch 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 plight whitethorn cause mistyping of blood groups which , in turn , whitethorn affect transfusion and transplantation proceduresThe ABO blood group system has been determined to follow a unique geographical diffusion (Fukumori et al , 1996 . Frequencies of individuals with blood type B ar know to be point(prenominal)ly richly-pitched in Asian countries , ranging up to 30 is specific populations such as the Himalayans .
The Himalayan soil has been reported to have a history of smallpox and bubonic plague epidemics , which ar specific medical examination illnesses that confer particular physiological responses in the body that blood types A and O are selected against (Yamamoto et al , 1993 Such selection is also associated with the development of resistance to the other antigens , thereof blood type B is said to be fixed in the area through and through the mechanism of genic driftInvestigations on the ABO locus has revealed that miry sequence variations occur within this region , resulting in substitutions of nucleotides bases that are presumably less susceptible to selection pressure , thus 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 transmitted mechanisms . Point mutations may have occurred in the consensus ABO locus due to recombinat ion 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 infinite populations . Recombination facilitates the generation of new variants of blood type B may also be enhanced by inter-lineage sequence channel , resulting in intermediate products of the B alleleBlood type B is strongly associated with specific medical diseases such as esophageal carcinoma , childish 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 referential in these populations because the physiological settings of these individuals are optimal for the fixation...If you want to switch on a full essay, order it on our website: OrderCustomPaper.com
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