The molecular characterization of the subgroup A3 remains unclear. Four unrelated A3 blood donors were studied. Family studies were possible in three of them. The A3 subgroup was defined by immunohaematological evaluation with four different commercially available serums. Exons VI and VII of the ABO gene, responsible for 91% of the catalytic active part of the glycosyltransferase, were amplified and subjected to direct sequencing. The results in all samples showed heterozygosity for the G261 deletion. In the A3 allele, the following associations were found: C467T mutation and 1060C deletion in one A3 blood donor and in another G829A and 1060C. In one case, only the 1060C deletion was demonstrated in the A3 allele. One blood donor presented the T646A and the G829A mutations in homozygosity. It was concluded that the A3 blood group is very heterogeneous at the molecular level.
Molecular characterization of glucose-6-phosphate dehydrogenase (G6PD) variants was carried out in 150 unrelated G6PD deficient blood donors from the region of Campinas, Brazil. By allele specific oligomer hybridization or digestion of exon 4 of the G6PD gene with the restriction endonuclease NlaIII, we detected the 202 G→A mutation in 146 individuals. This mutation was associated with the 376 G→A substitution and only one haplotype was observed in these individuals. Digestion of exon 6 with the restriction enzyme Mboll showed the presence of the Mediterranean variant in three individuals. Haplotype analysis showed, in all three samples, a T at nt 1311 and the C at nt 13 in intron 11 suggesting a European origin of this variant. By SSCP analysis and direct sequencing we detected the mutation nt 1003 G→A (335 Ala→Thr) in one blood donor. This mutation was previously described in a boy of Indian ancestry and the variant was denominated G6PD Chatam. The case described here has no Indian ancestry; thus, we presume that the mutations have arisen independently, although we do not know the haplotype of the Indian patient. The haplotype of our case was the most common observed in our population (Pvull, BspHl+, Pstl+, 1311C, NlaIII-). Thus, our data indicate that G6PD A- with the 202 G→A mutation is the most frequent G6PD deficiency in the population of southeastern Brazil. The remaining variants had a Mediterranean origin. These results are in agreement with the origin of the Brazilian population.
This study focused on clinical, hematological, and molecular aspects of sickle cell anemia pediatric patients from two different cites in Brazil. Seventy-one patients from São Paulo and Salvador, aged 3 to 18 years, were evaluated. Hematological analyses, betaS globin gene haplotypes, and alpha2 3.7kb-thalassemia were performed. Numbers of hospitalizations due to vaso-occlusive crises, infections, stroke, and cholelithiasis were investigated. São Paulo had more hospitalizations from vaso-occlusion, cholelithiasis, and stroke than Salvador. The Ben/CAR genotype predominated in both cities. Alpha2 3.7kb-thalassemia had a frequency of 28.2% in Salvador, mostly with Ben/CAR genotype (45.0%), while São Paulo had 22.5% with similar frequencies of the Ben/ CAR and CAR/CAR genotypes. Sickle cell anemia patients from São Paulo also had more episodes of stroke, which was observed among CAR/CAR, atypical, and BEN/CAR haplotypes. In Salvador stroke was only observed in the Ben/CAR genotype. Cholelithiasis had similar frequencies in the two cities. These data suggest a milder phenotype among patients in Salvador, possibly due to genetic, environmental, and socioeconomic factors. Further studies are needed to elucidate modulating factors and phenotype association.
and Kidd phenotypes in addition to ABO is used to prevent the alloimmunization to red blood cells (RBCs) antigens and as part of the antibody identification process in patients with β Thalassemia. However, phenotyping in these patients can be time consuming and difficult to interpret. In these situations, it would be valuable to have an alternative to hemagglutination tests to determine the patient's antigen profile. We used PCR-RFLP to genotype such patients. DNA was prepared from 50 patients with β Thalassemia who had been phenotyped by routine hemagglutination, and tested for Kell, Kidd, Duffy/ GATA mutation by PCR-RFLP. RHD/non-D was analysed by PCR product size associated to RHD gene sequence in intron 4 and exon 10/3'UTR. The genotyping assays were performed without knowledge of phenotype results. For RHD/non-D, 47 were RhD+ and RHD+/RHCE+, and 3 were RhD-and RHD-/RHCE+. For Kell, 48 kk were K2K2 and 2 Kk were K1K2. For Duffy, of 44 samples that had normal GATA box, 8 Fy(a+b-) were FYA/FYA, 15 Fy(a+b+) were FYB/FYB, and 19 Fy(a+b+) were FYA/FYB; of the other 4 samples 3 were FYA/FYB and heterozygous GATA mutation, and 1 Fy(a-b-) was FYB/FYB, homozygous GATA mutation. Two samples phenotyped as Fy(a+b-) that had normal GATA , presented the 265T/298 A mutations and two samples phenotyped as Fy(a-b+) were genotyped was FYA/FYB.. For Kidd , 15 Jk(a+b) were JKA/JKA, 12 Jk(a-b+) were JKB/JKB, and 20 Jk(a+b+) were JKA/JKB. Three samples phenotyped as JK(a+b+) were genotyped as JKB/JKB. Genotype is more accurate than phenotype for determination of blood groups in polytransfused patients with βThalassemia. Genotyping in these patients can be helpful to select antigen-negative RBCs for transfusion.
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