BackgroundThe Kell blood group system expresses high and low frequency antigens with the most important in relation to transfusion including the antithetic KEL1 and KEL2; KEL3 and KEL4; KEL6 and KEL7 antigens. Kell is a clinically relevant system, as it is highly immunogenic and anti-KEL antibodies are associated with hemolytic transfusion reactions and hemolytic disease of the fetus and newborn. Although required in some situations, Kell antigen phenotyping is restricted due to technical limitations. In these cases, molecular approaches maybe a solution. This study proposes three polymerase chain reaction genotyping protocols to analyze the single nucleotide polymorphisms responsible for six Kell antithetic antigens expressed in a Brazilian population. MethodsDNA was extracted from 800 blood donor samples and three polymerase chain reaction-restriction fragment length polymorphism protocols were used to genotype the KEL*1/KEL*2, KEL*3/KEL*4 and KEL*6/KEL*7 alleles. KEL*3/KEL*4 and KEL*6/KEL*7 genotyping was standardized using the NlaIII and MnlI restriction enzymes and validated using sequencing. KEL*1/KEL*2 genotyping was performed using a previously reported assay. ResultsKEL genotyping was successfully implemented in the service; the following distribution of KEL alleles was obtained for a population from southeastern Brazil: KEL*1 (2.2%), KEL*2 (97.8%), KEL*3 (0.69%), KEL*4 (99.31%), KEL*6 (2.69%) and KEL*7 (97.31%). Additionally, two individuals with rare genotypes, KEL*1/KEL*1 and KEL*3/KEL*3, were identified. ConclusionKEL allele genotyping using these methods proved to be reliable and applicable to predict Kell antigen expressions in a Brazilian cohort. This easy and efficient strategy can be employed to provide safer transfusions and to help in rare donor screening.

Background: Several centers have selected Black donors to prevent Rh alloimmunization of patients with sickle cell disease (SCD). As the Brazilian population is considered very admixed and race definition by self-declaration is questionable, this study aimed to compare RHCE diversity among patients with SCD and selected groups of Brazilian blood donors to define which group of donors would be the adequate red cell supply for patients with SCD.Method: We compared RHCE allele frequencies between patients with SCD and four groups of Brazilian blood donors: self-declared Black donors (SDB), donors with predominant African genetic markers (AAM), donors with weak D expression (WDD), and random donors (RDs). Variant RHCE alleles were identified using molecular protocols.Results: Among patients with SCD, 47% had at least one variant RHCE, in SDB and WDD this frequency was higher, 53% and 58.6%, respectively. In AAM and in RD the frequencies were 32% and 27.6%, respectively. In patients with SCD and SDB, the most common alleles were RHCE*ce.01, RHCE*ceVS.01, and RHCE*ceVS.02. WDD had a high frequency of RHCE*ceAR and highest frequency of variant RHCE in both alleles, followed by patients with SCD and SDB. Conclusion: This study showed that even in an admixed population the selection of SDB donors is the best choice of matching for transfusion support in patients with SCD. For specific RHCE alleles, selection of donors with weak D expression could be a good option.

Background and ObjectivesGerbich (GE) blood group system carries high‐frequency antigens and the absence of them leads to rare phenotypes: GE:−2,3,4, GE:−2,−3,4 and GE:−2,−3,−4. Their serological differentiation is limited and misclassification of Gerbich phenotypes may occur, but this can be avoided by molecular characterization. This study aimed to characterize the molecular background responsible for rare Gerbich phenotypes in Brazilian population.Materials and MethodsWe selected eight samples from patients with anti‐Ge, six from their relatives and nine samples with normal expression of Gerbich antigens. Serological tests were performed in gel and red blood cells (RBCs) were tested with anti‐Ge2 and anti‐Ge3. Monocyte monolayer assay (MMA) was performed. Molecular investigation was performed with allele‐specific polymerase chain reaction and DNA sequencing.ResultsPatient plasma samples reacted with all commercial RBCs. Patient RBCs showed negative results with anti‐Ge2 and anti‐Ge3. Using MMA two of eight antibodies were clinically significant. Exon 3 was not amplified in any of the patient samples and in two samples from relatives, suggesting the presence of GE*01.‐03/GE*01.‐03. By sequencing, we identified the genetic variability that interferes with the definition of deletion breakpoints, thus two options of genetic structure were suggested to be responsible for the GE:−2,−3,4 phenotype.ConclusionThis study showed for the first time the genetic diversity of GYPC alleles for carriers of Gerbich‐negative phenotypes in a Brazilian population and showed an unexpected prevalence of the GE:−2,−3,4 phenotype. It also demonstrated the importance of using molecular tools to correctly classify Gerbich phenotypes for selection of variants in antigen‐matched transfusions.