The Rh blood group system and its role in alloimmunization rate among sickle cell disease and sickle thalassemia patients in Iran

Molecular genotyping versus serological diagnosis for RH blood group typing in sickle cell patients

OBJECTIVES

High rate of alloimmunization in sickle cell disease (SCD) patients poses a significant challenge in finding compatible blood unit. Accurate determination of the blood group genotype of them can help reduce the alloimmunization risk. Tetra ARMS PCR is a novel method that has been utilized recently to investigate SNPs in diseases in a fast and reliable way.

METHODS

Our study included 104 SCD and sickle thalassemia (Sβ) patients referred to Baghaei-2-Hospital of Ahvaz in 2019 using a nonrandom sampling method. Blood samples were collected for serological and molecular tests. Rh genotyping was performed using Tetra ARMS PCR and compared with the serological results.

RESULTS

Based on the Tetra ARMS PCR method, out of 104 patients, 7 (6.7%) were d/d, 40 (38.5%) were D/d, 57 (54.8%) were D/D, 25 (24%) were C/C, 59 (56.7%) were C/c, 20 (19.3%) were c/c, 4 (3.8%) were E/E, 25 (24%) were E/e, and patients 75 (72.2%) were e/e. There were discrepancies in the serological and molecular results for 11 patients.

CONCLUSION

Use of Tetra ARMS PCR in combination with serological methods for determining the Rh blood group system in donors and transfusion-dependent patients represents a remarkable transformation in the field of immunohematology.

Hemolytic disease of the fetus and newborn due to minor blood group alloimmunization in a mother of sickle cell disease with multiple alloantibodies

Hemolytic disease of the fetus and newborn is due to maternal IgG antibodies that transport through the placenta and destroy neonatal red cells. A mismatch of antigens between mother and fetus causes isoimmunization resulting in mild anemia, which may progress to fetal hydrops in the intrauterine period and severe hyperbilirubinemia to kernicterus in neonates. The isoimmunization is mainly caused by Rh-D and ABO antibodies. In this case report, we found neonatal hyperbilirubinemia due to the presence of anti-c alloantibody previously developed in a sickle cell disease (SCD) pregnant female. It is an unusual case of fetal hyperbilirubinemia due to minor blood group alloimmunization in a SCD needing exchange transfusion. Multi-transfused patients should be counseled regarding the need to perform antibody screening frequently before pregnancy for better treatment of both mother and child.

Variant RHD alleles and Rh immunization in patients with sickle cell disease

RH diversity among patients and donors contributes to Rh immunization despite serologic Rh-matched red cell transfusions. Anti-D can occur in D+ patients with RHD variants that encode partial D antigens. Anti-D has also been reported in patients with conventional RHD transfused primarily with units from Black donors who frequently have variant RHD. We report 48 anti-D in 690 D+ transfused individuals with sickle cell disease, categorized here as expressing conventional D, partial D or D antigen encoded by RHD*DAU0. Anti-D formed in a greater proportion of individuals with partial D, occurred after fewer D+ unit exposures, and remained detectable for longer than for those in the other categories. Among all anti-D, 13 had clinical or laboratory evidence of poor transfused red cell survival. Most individuals with anti-D were chronically transfused, including 32 with conventional RHD who required an average of 62 D- units/year following anti-D. Our findings suggest that patients with partial D may benefit from prophylactic D- or RH genotype-matched transfusions to prevent anti-D. Future studies should investigate whether RH genotype-matched transfusions can improve use of valuable donations from Black donors, reduce D immunization and minimize transfusion of D- units to D+ individuals with conventional RHD or DAU0 alleles.

The Frequency of Rh Phenotype and Its Probable Genotype

Aims and objectives: Our goal is to disseminate data on the distribution pattern of Rh antigen, its phenotypes, and the likely genotypes of these genetic variants in the Pakistani population.

Methodology: This study was a cross-sectional research project. Patients’ demographic statistics, such as age and gender, were gathered from their medical information. Blood group, disease, RhD, and other antigen frequency, phenotype, and probable genotype were considered variables. All blood samples were phenotyped for Rhesus antigens (D, C, c, E, and e), and the test was carried out using the tubing technique.

Results: According to gender distribution, most of the patients were males, with 131 frequencies (57.7%), while females had 42.35%. The most common phenotype was DCCee, with its probable genotype DCe/DCe (R1 R1) (34%), followed by DCcee, with probable genotype DCe/ce (R1 r) (29.1%); the least common phenotype was ddCcee, with its probable genotype Ce/ce (r ' r) (0.4%).

Conclusion: It is concluded that the DCCee phenotype was the most common with its probable genotype DCe/DCe, while the least common phenotype was ddCcee with its probable genotype Ce/ce.

Prevalence of Rh and K phenotypes among blood donors from different ethnicities in Samtah (Southwestern Region) Saudi Arabia

INTRODUCTION

Rh and Kell blood group systems are amongst the most important blood group systems; being highly immunogenic after ABO system. The aim of this study was to evaluate the frequencies of Rh antigens, haplotypes and K antigen among blood donors belonging to various ethnicities in Samtah, Jazan, Saudi Arabia.

METHODS

This study was conducted during January 2019 and August 2020 at Samtah General Hospital, Samtah. Records of all blood donors recruited during this period were included for data acquisition. A total of 4977 blood donors' records were reviewed and data were analysed. A total of 3863 donors' results were considered in the final analysis.

RESULTS

In comparison to Saudi blood donors, C antigen was less frequent in Sudanese donors (69.7% and 34.0%), the c antigen was less frequent in Indian (79.2% and 59.3%) and Philippine (79.2% and 40.0%) donors and more frequent in Sudanese (79.2% and 97.9%) donors, the E antigen was less frequent in Yemini (27.0% and 19.5%) and the e antigen was more frequent in Yemini (96.7% and 99.2%) donors. The DcE haplotype was less frequent (3.1% and 0.7%) and the ce haplotype was more frequent (4.3% and 7.6%) in Yemini donors. The K antigen was less frequent in Pakistani (11.9% and 4.1%; p = .041) and Indian (11.9% and 1.9%; p = .023) donors.

CONCLUSION

Rh and K antigens showed marked variations in their frequencies among blood donors of different ethnicities. Utilization of blood from various ethnicities warrant extended phenotyping of Rh and K antigens to avoid the risk of alloimmunization in multiply transfused patients.