RHD allelic identification among D-Brazilian blood donors as a routine test using pools of DNA

BACKGROUND

RHD alleles leading to a reduced expression of D antigen of the red blood cell (RBC) surface may be erroneously typed as D- by serology and may cause anti-D immunizations when transfused to recipients.

METHODS

To determine the occurrence of such alleles among apparent D- blood donors, molecular typing was implemented as a routine test using a pool of DNA. A total of 2,450 pretyped D- samples were tested in pools of 10 for the RHD-specific polymorphism in intron 4 and exon 7. Samples in polymer chain reaction (PCR) positive pools were individually reevaluated by exon-specific PCRs, sequencing, and serologic methods.

RESULTS

Among 2,450 serologically D- blood donor samples tested, 101 (4.1%) carried the RHD gene. Nonfunctional RHD (RHDψ, RHD*CE(2-9)-D, and RHD*CE(3-7)-D), different weak D alleles such as RHD*weak D type 1, RHD*weak D type 4.3, RHD*weak D type 5, RHD*weak D type 38, and RHD*DEL were identified.

CONCLUSION

We employed a PCR-based assay for RHD as a routine test using pools of ten DNA blood donor samples. The integration of RHD genotyping into the routine screening program using pools of DNA samples was straightforward. As a consequence, 19 (0.8%) blood donors carrying a weak D and Del phenotypes with the potential of causing anti-D immunizations in recipients were reclassified as D+. For each population, it would be necessary to adapt the RHD genotyping strategy to the spectrum of prevalent alleles.

Prevalence of RHD*DOL and RHCE*ce(818T) in two populations

The alleles RHCE*ceBI (RHCE*ce 48C, 712G, 818T, 1132G) and RHCE*ceSM (RHCE*ce 48C, 712G, 818T) encode the low-prevalence Rh antigen STEM. These alleles frequently travel in cis with RHD*DOL. To estimate the frequency of these alleles, we tested a total of more than 700 samples in two populations. Blood samples were obtained from patients with sickle cell disease and from blood donors of African descent. DNA extractions and analyses were performed by standard methods. In the United States, none of 70 patient samples had the RHCE*818 nucleotide change. Two of 220 donors (frequency of 0.009) were heterozygous for RHCE*818C/T (RHCE*ceBI). One of these samples had RHD/RHD*DOL and the other had RHD/RHD*DOL-2. In these 290 samples, no other RHD*DOL alleles were found. In Brazil, 1 of 244 patients with sickle cell disease (frequency of 0.004) and 1 of 171 donors (frequency of 0.006) were heterozygous for RHCE*818C/T (RHCE*ceBI). Testing of more than 500 additional samples from people of African descent, selected because they had a diverse range of common and variant RHCE alleles, did not reveal a sample with RHD*DOL or RHD/RHD*DOL-2 in the absence of RHCE*ce(818T). Although the numbers are small, our study shows that in the United States, the frequency of RHCE*818T is 0.007 (2 in 290 samples) and in Brazil it is 0.004 (2 in 515 samples). The four RHCE*818T alleles were RHCE*ceBI.

DNA array analysis for red blood cell antigens facilitates the transfusion support with antigen-matched blood in patients with sickle cell disease

BACKGROUND

Blood samples from patients with sickle cell disease (SCD) present to transfusion service with numerous antibodies, making the searching for compatible red blood cells (RBC) a challenge. To overcome this problem we developed an effective strategy to meet needs of supplying RBC-compatible units to SCD patients using DNA arrays.

METHODS

We selected DNA samples from 144 SCD patients with multiple (receiving > 5 units) transfusions previously phenotyped for ABO, Rh(D, C, c, E, e), K1, Fy(a) and Jk(a). We also selected DNA samples from 948 Brazilian blood donors whose ABO/RhD phenotype matched that of the patients. All samples were analysed by DNA array analysis (HEA Beadchip(TM), Bioarray Solutions) to determine polymorphisms associated with antigen expression for 11 blood group systems (Rh, Kell, Kidd, Duffy, MNS, Dombrock, Lutheran, Landsteiner-Wiener, Diego, Colton, Scianna); and one mutation associated with haemoglobinopathies.

RESULTS

Based on genotype results we were able to predict phenotype-compatible donors needed in order to provide compatible units to this group of patients. Based on their ABO/Rh phenotype we were able to find in this pool of donors compatible units for 134 SCD patients.

CONCLUSION

Blood group genotyping by DNA array contributes to the management of transfusions in SCD patients by facilitating the transfusion support with antigen-matched blood. It has the potential to improve the life of thousands of SCD-transfused patients by reducing mortality due to transfusion reactions and immunization.

JAL (RH48) blood group antigen: serologic observations

BACKGROUND

JAL (RH48) is a low-prevalence antigen in the Rh blood group system and anti-JAL has caused hemolytic disease of the newborn. JAL is associated with either a haplotype carrying depressed C and e antigens or one carrying depressed c and e antigens. Blood samples from JAL+ people were tested, published serologic findings were confirmed, serologic studies were extended to include expression of other Rh antigens, and the antibody specificities produced by three sensitized JAL+ probands are reported.

STUDY DESIGN AND METHODS

Red blood cell (RBC) samples from 17 (12 probands) JAL+ persons were tested by hemagglutination using standard methods.

RESULTS

RBCs from both the Caucasian JAL+ probands had the (C)(e) haplotype and weakened C, e, hr(B), and hr(S) antigens. JAL+ samples from black persons had the (c)(e) haplotype and expressed weakened c, e, f, V, VS, hr(B), and hr(S) antigens. Plasma from three sensitized c+e+ JAL+ probands contained alloanti-c, alloanti-e, or alloantibody of apparent anti-Rh17 specificity. This study shows that this alloanti-Rh17-like antibody recognizes the high-prevalence antigen antithetical to JAL that has been named CEST.

CONCLUSIONS

The presence of the JAL antigen has a quantitative (weakening) effect on the expression of C, e, hr(B), and hr(S) antigens in Caucasian persons and of c, e, f, V, VS, hr(B), and hr(S) antigens in people of black African ancestry. A qualitative effect also was demonstrated by the presence of alloanti-c or alloanti-e in the plasma of two transfused c+e+ patients and by an antibody (anti-CEST) that recognizes the high-prevalence antigen antithetical to JAL.

Consortium for Blood Group Genes (CBGG): 2008 report

The Consortium for Blood Group Genes is a worldwide organization whose goal is to have a vehicle to interact, establish guidelines, operate a proficiency program, and provide education for laboratories involved in DNA and RNA testing for the prediction of blood group, platelet, and neutrophil antigens.

Molecular analyses of GYPB in African Brazilians

The molecular background of variant forms of GYPB is not well studied in Brazilians of African descent. The present study was carried out to determine the molecular bases of the S-s- phenotype and the frequency of GYPB*S silent gene for the S-s+ phenotype in a blood donor population of African Brazilians. In this study, 165 blood samples from African Brazilians (Northeastern Brazil) who phenotyped as S-s- (n = 17) and S-s+ (n = 148) by hemagglutination were selected. Allele-specific (AS)-PCR and PCR-restriction fragment length polymorphism (RFLP) were used to identify the variant forms of GYPB. In 13 of 17 S-s- samples (76.5%), both GYPB were deleted. In 137 of the 148 S-s+ samples (92.6%), the AS-PCR was consistent with the S-s+ phenotype. In 4 of the S-s- samples (23.5%) and 11 of the S-s+ samples (7.4%), the AS-PCR showed the presence of a GYPB*S allele associated with silencing of S. In the 4 donors with the S-s- phenotype, there was homozygosity (or hemizygosity) for the GYP(P2) allele (n = 2), homozygosity (or hemizygosity) for the GYP(NY) allele (n = 1), and heterozygosity for the GYP(P2) and GYP(NY) alleles (n = 1). In the 11 donors with the S-s+ phenotype, there was heterozygosity for GYP(P2) allele (n = 8) and heterozygosity for GYP(NY) allele (n = 3). This study reports for the first time the molecular mechanisms responsible for the S-s- phenotype in a population of African Brazilians and provides new information about the frequency and molecular bases of the GYPB*S silent gene (7.4%) in this population.

Molecular studies of DO alleles reveal that JO is more prevalent than HY in Brazil, whereas HY is more prevalent in New York

Because of the scarcity of anti-Hy and anti-Jo(a), hemagglutination typing for the Dombrock blood group system antigens, Hy and Jo(a), is not feasible. The molecular bases associated with these antigens have been determined, making it possible to distinguish HY and JO from wild-type DO. This provides a tool to predict the probable phenotype of patients and to screen for antigen-negative donors. PCR-RFLP assays and a microchip assay were used to determine the frequency of HY and JO alleles in donors from Brazil and New York. DNA from random Brazilian donors, 288 by PCR-RFLP and 599 by the bead array method (BeadChip, BioArray Solutions, Warren, NJ), was tested to determine 323G/T (HY+/HY-) and 350C>T (JO+/JO-) single-nucleotide polymorphisms. In New York, 27,226 donors who self-identified as being African American were tested by hemagglutination with anti-Gy(a). Nonreactive and weakly reactive samples were tested by PCR-RFLP for the same alleles as listed above. In Brazil, 30 (3.4%) of the samples were JO/DO and 13 (1.4%) were HY/DO. In New York, of the samples that had HY or JO alleles, 14 were homozygous HY/HY 132 were heterozygous HY/DO, 13 were heterozygous HY/JO, 14 were heterozygous JO/DO, and 3 were homozygous JO/JO. These results show that in donors from Brazil, JO (30 alleles) is more than twice as prevalent as HY (13 alleles), whereas in donors from New York, HY (173 alleles) was more than five times more common than JO (33 alleles).

Consortium for Blood Group Genes (CBGG): 2007 report

The Consortium for Blood Group Genes is a worldwide organization whose goal is to have a vehicle to interact, establish guidelines, operate a proficiency program, and provide education for laboratories involved in DNA and RNA testing for the prediction of blood group, platelet, and neutrophil antigens.

Dombrock gene analysis in Brazilian people reveals novel alleles

BACKGROUND AND OBJECTIVES

The Doa and Dob polymorphisms are associated with three single nucleotide polymorphisms (SNPs) in exon 2 of the DO gene: 378C/T, 624T/C and 793A/G for the DOA and DOB alleles, respectively. The SNPs 350C/T (JO allele) and 323G/T (HY allele) are associated with the Jo(a-) and Hy-negative phenotypes. Recently, two new DO alleles [DOB-SH (378C, 624C, 793G) and DOA-HA (378T, 624T, 793A)] were identified using microarray technology. Although the molecular background of Dombrock alleles is well defined, no studies have been conducted in the Brazilian population.

MATERIALS AND METHODS

We employed polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP)-based assays and a microarray assay to determine the frequency of the DO alleles (DOA, DOB, HY1, HY2 and JO) in Brazilians. We tested DNA of 288 Brazilians from three different ethnic groups by PCR-RFLP to determine the 793A/G (DOA/DOB), 323G/T (HY), 350C/T (JO) and 898C/G (HY1/HY2) SNPs. We also tested DNA from 162 blood donors by using the HEA Beadchip assay to determine the 378C/T, 624T/C, 793A/G (DOA/DOB), 350C/T (JO allele) and 323G/T (HY) SNPs.

RESULTS

Two novel allele combinations were found in our samples: the DOB allele (793G and 323G) associated with 898G (DOB-WL); and an allele carrying the nucleotides 378C, 624C, 793A and 323G (DOA-SH). We also found the DOB-SH and DOA-HA.alleles recently reported.

CONCLUSIONS

Our data demonstrate high heterogeneity of DO alleles in the Brazilian population. Our study also highlights the importance of testing a cohort of different populations to determine DO haplotypes and of establishing reliable genotyping tests for predicting Doa/Dob status.

Rhnull syndrome: identification of a novel mutation in RHce

BACKGROUND

The deficiency of Rh proteins on red blood cells (RBCs) from individuals of the Rh(null) amorph type are the result of homozygosity for a silent RHCE in cis with a deleted RHD. A novel mutation in RHce was identified in two Caucasian Brazilian girls with the amorph type of Rh(null) who were born to parents who were first cousins.

STUDY DESIGN AND METHODS

RBCs from the Rh(null) sisters and from family members were analyzed by serology and flow cytometry with specific antibodies. Genomic DNA and transcripts were tested by polymerase chain reaction and sequence analysis.

RESULTS

Rh(null) RBCs were nonreactive with anti-Rh and anti-LW. Molecular analyses showed a deletion of RHD and of one nucleotide (960/963; GGGG-->GGG) in exon 7 of the RHce. This deletion introduced a frameshift after Gly321, a new C-terminal sequence, and a premature stop codon, resulting in a shorter predicted protein with 357 amino acids.

CONCLUSION

The detection of a unique RHce transcript indicated that the two sisters were homozygous, whereas the other family members were heterozygous for the mutation. A novel mutation resulting in the amorph Rh(null) with loss of Rh antigen expression is described.

A novel FY allele in Brazilians

The GATA box single nucleotide polymorphism (SNP) at position -33 (T>C) in Blacks silences the expression of FY*B in erythrocytes, and the substitution 265 C>T, together with 298 G>A, weakens the Fy(b) antigen (Fy(x)). Individuals with these phenotypes/genotypes who receive Fy(b+) blood are unlikely to be alloimmunized to Fy(b) because, in the presence of 265 T, the Fy(b) antigen is expressed, and in the case of -33 C, other tissues express Duffy protein and probably the Fy(b) antigen. We studied samples from 361 blood donors (182 of African ancestry and 179 of Caucasian ancestry) by haemagglutination and polymerase chain reaction (PCR) restriction fragment length polymorphism (RFLP). Forty Caucasian and 130 donors of African ancestry were serologically Fy(b-); among these, the majority of the donors of African ancestry had FY*B with the GATA SNP, while the majority of Caucasians typing Fy(b-) had FY*B with 265 T/298 A SNPs. Six of the Fy(b-) donors (three Africans and three Caucasians) had both GATA and 265/298 SNPs, and six donors of Caucasian ancestry apparently had a GATA SNP. Samples from two donors - one African and one Caucasian with an unusual MspA1I-RFLP pattern - were sequenced and found to have a novel SNP (145 G>T) co-existent with 265 C>T and 298 G>A SNPs. These findings highlight the importance of establishing the incidence and nature of molecular events that impact on Duffy expression in different populations.

High frequency of partial DIIIa and DAR alleles found in sickle cell disease patients suggests increased risk of alloimmunization to RhD

We have set out to determine the frequency of DIIIa and DAR alleles among sickle cell disease (SCD) patients. These D variants permit the unexpected development of antibodies to RhD among individuals who are otherwise classified as RhD+. DNA samples from 130 SCD patients were tested for 455A>C (specific for DIIIa), 602C>G, 667T>G (common for both DIIIa and DAR) and 1025T>C (specific for DAR) by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and sequence analysis. The PCR-RFLP showed that 12 (9.2%) of the SCD patients were carrying DIIIa and DAR alleles. Genomic DNA analysis performed by sequence showed that three samples were heterozygous DIIIa (2.3%), seven heterozygous DAR (4.6%) and two (1.5%) samples carried a partial D with four mutations: 455A>C (heterozygous), 602C>G and 667T>G (homozygous) and 1025T>C (heterozygous), indicating compound heterozygosity for one DIIIa allele and one DAR allele. The predicted phenotypes of eight (6.2%) SCD patients were DIIIa, DAR and DIIIa/DAR. Three patients were anti-D immunized (DAR, n = 1; DIIIa/DAR, n = 2). These findings suggest that SCD patients who are candidates for chronic transfusion may benefit from genotyping for DIIIa and DAR to prevent alloimmunization.