rev bras hematol hemoter. 2016;38(3):182–183
w w w . r b h h . o r g
Revista
Brasileira
de
Hematologia
e
Hemoterapia
Brazilian
Journal
of
Hematology
and
Hemotherapy
Scientific
comment
Blood
group
polymorphisms
in
Brazil
夽
Lilian
Castilho
∗UniversidadeEstadualdeCampinas(Unicamp),Campinas,SP,Brazil
Bloodgroupantigensarepolymorphismsofproteinsand car-bohydratesonthesurfaceofredbloodcells(RBC)withthe distributionofallelesvaryingbetweendifferentethnicgroups andpopulations.Byusingthegeneticinformationprovidedby thehumangenomeproject,themolecularbasisofmostblood group genes encoding blood group systems, antigens and phenotypeshavebeenelucidatedandnowadaysthe molec-ularbasisisknownforthe308antigensclusteredinthe36 bloodgroupsystemsrecognizedbytheInternationalSociety ofBloodTransfusion(ISBT).1Thisknowledgehasprovidedthe
meanstopredictredcellantigensandphenotypesinorderto identifymoreextensivelymatchedbloodforchronically trans-fusedpatients. However,dataon theprevalenceofvarious bloodgroupantigensindifferentpopulationsareessentialfor estimatingtheavailabilityofbloodcomponents.
Theavailablewealthofserologicallydefinedvariantshas contributedtotherapidratewithwhichthegeneticdiversity ofbloodgroupgeneshasbeen revealed.Initially,molecular informationassociated to each variant was obtained from onlyasmallnumberofsamplesandappliedtoDNA analy-siswiththehopefulassumptionthatthemolecularanalysis wouldcorrelatewithRBCantigentyping.Bygatheringmore information,itbecameobviousthatmanymolecularevents resultinthegenotypeandRBCphenotypebeingapparently discrepant.2Therefore,alargenumberofpeoplefroma
vari-etyofethnicbackgroundsneedtobestudiedtodetermine theoccurrenceofparticulargenotypesandtoestablishmore reliably the correlationbetween blood groupgenotype and phenotype.
Hemagglutinationhasidentifiedmanyphenotypicvariants and molecular analysishasrevealed remarkable variations within variants. Investigations on the automation of SNP
DOIoforiginalarticle:http://dx.doi.org/10.1016/j.bjhh.2016.04.005.
夽
SeepaperbyCostaetal.onpages199–205.
∗ Correspondenceto:Hemocentro,Unicamp,RuaCarlosChagas480,CaixaPostal6198,BarãoGeraldo,13081-970Campinas,SP,Brazil.
E-mailaddress:castilho@unicamp.br
and DNA sequence analysis are ongoing and the potential forgenotypinglarge numbersofsampleshasalready been achieved.3 Several assays forblood groupgenotyping have
beendevelopedtopredictthebloodgroupantigenprofileofan individualandwiththedevelopmentofseveralcommercial kits, moleculartesting isbeing performed inmany labora-tories worldwide tosolve clinical problems that cannotbe addressedbyhemagglutination.
Theidentification ofthemolecular basisofblood group antigenshasalsoprovidedaninsightintothegenerationof gene diversity in humans showing that blood group poly-morphismscanbeusefulmarkersofgeneticdifferentiation ofhumanpopulations. Theeffectsofmutationsonprotein expression and the relative ease of identifying individuals bearing variant alleles has led to the proposal that genes encodingbloodgroupantigensareanimportantandunique resourceforstudiesonhumanDNAvariation.4
TheBrazilianpopulationisofheterogeneousethnicorigin. Thisdiverse populationisalsounevenlydistributedwithin a country of continental dimensions. Besides the Native-Americanpopulation,Brazilreceivedmanyimmigrantsfrom Portugal, Italy,Spain,Germany, Japanand the MiddleEast. During the slave tradefrom the 16th to the 18th century Brazilreceivedapproximately4millionAfricans,mainlyfrom Angola,Congo and Mozambique,who settled inalmost all regionsofthecountry.5Theintenseprocessofmiscegenation
made the Brazilian population unique in its ethnic back-ground.Inamulti-ethnicpopulation,suchasthatofBrazil, thefrequenciesofthedifferentbloodgroupantigensvary sig-nificantly.Genotypingstudiesinthispopulationhaveshown thatthebloodgrouppolymorphismsdiffersignificantlyfrom otherpopulations6,7andstudiesinsidethecountryhavealso
http://dx.doi.org/10.1016/j.bjhh.2016.04.008
rev bras hematol hemoter. 2016;38(3):182–183
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shownaheterogeneousdistributionofbloodgroupallelesand variantsbetweengroupsofpeoplefromdifferentregions.8,9
Moreover,thehigh degreeofgeneticmixtureinthe Brazil-ianpopulation facilitatesthe generationofnewalleles.10,11
Therefore,studiesonthedistributionofbloodgroupalleles andvariants indonorsand patientsfrom differentregions ofBrazilcanreportthefrequenciesofdefinedpolymorphic bloodgroupantigensthatfunctionasreceptorsforparasites, maptherarephenotypesacrossthecountryandcontribute intheselectionofthe mostadequateblood componentfor chronicallytransfusedpatients.
Conflicts
of
interest
Theauthordeclaresnoconflictsofinterest.
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