Genotipagem do locus ABO (9q34.1) em doadores de sangue da região noroeste do Estado de São Paulo

Abstract

Os avanços da genética molecular permitiram o entendimento das bases moleculares do locus ABO. Considerando sua importância como marcador genético e suas aplicações, o objetivo deste estudo foi verificar a distribuição dos genótipos ABO em uma amostra da população brasileira oriunda da região noroeste do Estado ArtigoIntrodução O maior sistema de aloantígenos expressos nos eritrócitos e em outros tecidos humanos constitui-se de quatro fenótipos definidos pelas combinações de dois antígenos carboidratos A e B e de dois anticorpos plasmáticos anti-A e anti-B. Os indivíduos com os fenótipos A, B e AB expressam glicosiltransferases específicas que convertem o antígeno H em A ou B, mas aqueles com fenótipo O são incapazes de modificar a estrutura desse antígeno (1).As glicosiltransferases que sintetizam os antígenos A e B são codificadas pelos genes que ocupam o locus ABO, os quais são herdados pelos princípios mendelianos (2) . O modelo com três genes A, B e O proposto para explicar seu modo de herança foi confirmado com a clonagem e o seqüenciamento do locus ABO no início dos anos noventa e a partir desses conhecimentos, as diferenças na seqüência de nucleotídeos dos genes tornaram-se conhecidas e passíveis de serem utilizadas na genotipagem de populações (3, 4).

Frequency of ABO blood group system polymorphisms in Plasmodium falciparum malaria patients and blood donors from the Brazilian Amazon region

“…On the other hand, previous studies in Southeast Brazil (Mattos et al, 2001) have shown lower O 1variant allele frequencies than those found in our sample, probably because the indigenous contribution in this region of country is the smallest. Along the same line, the frequency of the A phenotype reaches values around 35%, and the A allele frequency is more than 0.25 in these populations (Mattos et al, 2001), while in our sample of the North region the frequencies were 21.2 and 0.13%, respectively.…”

“…Comparing the Brazilian population data, our results show that O 1variant allele frequencies are lower than the frequencies reported for some Amerindians and higher than those for populations of Caucasian and African ancestry (Olsson et al, 1998), probably due to the influence of Portuguese colonization in the northern region of Brazil as well as the presence of Amerindians (Batista dos Santos et al, 1999). On the other hand, previous studies in Southeast Brazil (Mattos et al, 2001) have shown lower O 1variant allele frequencies than those found in our sample, probably because the indigenous contribution in this region of country is the smallest. Along the same line, the frequency of the A phenotype reaches values around 35%, and the A allele frequency is more than 0.25 in these populations (Mattos et al, 2001), while in our sample of the North region the frequencies were 21.2 and 0.13%, respectively.…”

“…The ABO genotyping was assessed in 240 samples by amplifying fragments covering exons 6 and 7 using polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP). Moreover, a subset of peripheral blood samples from 30 P. falciparum-infected individuals and 27 blood donors were evaluated for the heterogeneity of the O alleles as previously described (Mattos et al, 2001). Briefly, four PCR were used.…”

Non-association between anti-Toxoplasma gondii antibodies and ABO blood group system

“…Since screening for T. gondii antibodies and ABO blood group system phenotyping are compulsory for pregnant women in Brazil, we assembled data from the medical records of women who gave birth in our hospital. The background of the series concerning ethnicity, age and ABO blood groups is representative of the geographic area in which the study was carried out (13,14).…”

ABO, Lewis, secretor and non-secretor phenotypes in patients infected or uninfected by the Helicobacter pylori bacillus

“…3 Recently, Mattos et al demonstrated that the ABO blood groups among Brazilians are highly polymorphic when analyzed by molecular methods. 4 Among the first epidemiological studies to establish associations between blood groups and diseases, there were some demonstrations of high frequencies of the O blood group and non-secretor phenotype of ABH antigens among patients suffering from peptic ulcers. 5,6 It was later shown that the Helicobacter pylori bacillus is the main etiologic agent associated with gastric ulceration, being present in more than 80% of patients with this disease.…”