Molecular matching for patients with haematological diseases expressing altered RHD-RHCE genotypes.

BACKGROUND AND OBJECTIVES: The high homology and the inverted orientation of RHD and RHCE may give rise to non-functional and aberrant RH alleles. RH genotyping is used to screen RH matched donors to African descent patients. This study aimed to define a strategy for testing RHD and RHCE variants in blood donors to provide compatible units for transfusion of patients with haematological diseases. MATERIALS AND METHODS: Samples from 132 patients [101 Sickle cell disease (SCD), 14 myelodysplastic syndrome (MDS), 17 acute myelogenous leukaemia (AML)] and 198 Brazilian donors were studied. Major blood group alleles, RHD, RHCE alleles and RHD zygosity were determined by the blood-MLPA assay. Sequencing was performed to determine RHD and RHCE variant subtypes. A match was an RH genotype that did not encode Rh antigens absent in the patient, along with matching for ABO, MNS, KEL, FY, JK and DI antigens. RESULTS: Overall, 7·6% of blood donors and 17.4% of patients presented RH genotypes that predict expression of partial Rh antigens or lack of high prevalence Rh antigens. From 23 patients with clinically relevant RH genotypes, 15 had available matched donors. CONCLUSION: We report the presence of clinically relevant RH genotypes in SCD and in non-SCD patients. In our admixed population, many patients carry variant RHCE alleles in heterozygosity with normal RHCE alleles. Thus, our results suggest that donors could be selected based on the normal RH allele.

HNA-3 gene frequencies in Brazilians and a new polymerase chain reaction-restriction fragment length polymorphism method for HNA-3a/3b genotyping.

BACKGROUND: HNA-3 antigens are the result of a rs2288904 single-nucleotide polymorphism (SNP) in the CTL2, and the HNA-3a and HNA-3b variants are encoded by a guanine and adenine at Nucleotide Position 461. Anti-HNA-3 are involved in severe transfusion-related acute lung injury reactions and in neonatal alloimmune neutropenia. Since the distribution of the HNA-3 system was unknown in South Americans, in this study we determined the frequency of the HNA-3 alleles in Brazilians. STUDY DESIGN AND METHODS: DNA of 500 blood donors, 120 Xikrin Amerindians, 74 Japanese individuals, and 124 African Brazilians were genotyped for rs2288904 by a polymerase chain reaction (PCR)-restriction fragment length polymorphism assay. The PCR product was digested with enzyme Taq(α) 1, specific to nucleotide guanine (HNA-3a). RESULTS: The results showed that the frequencies of the HNA-3a/HNA-3b alleles were 0.81/0.19 in blood donors, 1.00/0.00 in Amerindians, 0.63/0.37 in Japanese, and 0.85/0.15 in African Brazilians. All 81 individuals genotyped as HNA-3a/a did not present the SNP c.457T by molecular sequencing. CONCLUSION: The frequencies of HNA-3 genotypes in Brazilian blood donors is similar to that described in Caucasians; however, all Amerindians were HNA-3a/a, African Brazilians showed a lower frequency of HNA-3b/b, and Japanese had a higher prevalence of HNA-3b/b, suggesting that they may be at risk for developing anti-HNA-3a alloantibodies.