RHD Genotyping by Molecular Analysis of Hybrid Rhesus box in RhD-Negative Blood Donors from Iran

Molecular Background of RhD-positive and RhD-negative Phenotypes in a Saudi Population

Background

The RHD gene is one of the most complex blood group genes. The molecular background of the RHD gene in RhD-negative and RhD-positive individuals varies within and among different populations. Knowing the molecular basis of the RHD gene in a specific population is required to establish effective genotyping methods. While the molecular basis has been revealed in many ethnicities, such as Caucasians and Black Africans, it still requires elucidation in Arabs.

Objectives

The aim of this study was to gain insights into the molecular basis of RhD-positive and RhD-negative phenotypes in Saudi donors.

Materials and Methods

Conventional serological tests were used to determine the Rh phenotypes in 136 Saudi donors by typing D, C, c, E, and e antigens. Multiplex-PCR and Single Specific Primer-PCR were used to detect the presence of exons 3, 4, and 7 and the hybrid Rhesus box gene, respectively, in RhD-negative and/or RhD-positive samples.

Results

Of the 136 samples, 70 were RhD positive and 66 were RhD negative. None of the RhD-negative donors had any of the three tested exons, whereas the hybrid Rhesus box gene was detected in all, indicating the zygosity status of the RHD deletion allele. The hybrid Rhesus box gene was detected in 79% of the RhD-positive individuals, suggesting high frequencies of RHD-negative haplotypes.

Conclusions

The study findings indicate that Saudis with the RhD-negative phenotype are likely to have an entire RHD deletion in the homozygous state. However, a more comprehensive analysis of variant RHD alleles in the Saudi population is required to implement effective and dedicated molecular RHD typing strategies.

Polymorphisms in the promoter regions of RHD and RHCE genes in the Chinese Han population

BACKGROUND AND OBJECTIVES

The Rh blood group system is the most polymorphic human blood group system. Previous studies have investigated variants in the RHD and RHCE promoter. The relevance of these variants to the Chinese Han population is further clarified in this study.

MATERIALS AND METHODS

In total, 317 donors (223 Rh D-positive [D+], including 20 Del and 94 Rh D-negative [D-]) were randomly selected. The promoter regions and exon 1 of RHD and RHCE were amplified through polymerase chain reaction (PCR) whose products were directly sequenced using forward and reverse primers.

RESULTS

Expected PCR products of the RHD promoter and exon 1 were amplified in 223 D+ individuals, including 20 Del individuals, and were absent in 81 of 94 D- individuals. Expected PCR products of RHCE were observed in all donors. Two single nucleotide variants (SNVs) were observed in the RHD promoter region. Moreover, 11 SNVs were observed in the promoter and exon 1 of RHCE. rs4649082, rs2375313, rs2281179, rs2072933, rs2072932, rs2072931 and rs586178 with strong linkage disequilibria were significantly different between the D+ and D- groups. [A;C] was the most common haplotype in the RHD promoter (NC_000001.11:g.[-1033A>G;-831C>T]). [G;T;T;A;T;A;C;G;A;C;G] was the most predominant haplotype in both total and D- groups. In D+ individuals, [A;C;T;G;C;G;C;G;C;C;C] was the most frequent haplotype in the RHCE promoter (NC_000001.11:g.[-1080A>G;-958C>T;-390T>C;-378G>A;-369C>T;-296G>A;-144C>G;-132G>A;-122C>A;28C>T;48C>G]).

CONCLUSION

We speculate that the SNVs/haplotypes found in this article cannot significantly affect gene expression. The present study findings should help elucidate the molecular basis of the polymorphic expression of RHD and RHCE promoter regions.

RHD Genotyping of Rh-Negative and Weak D Phenotype among Blood Donors in Southeast Iran

Background: The D antigen is a subset of Rh blood group antigens involved in the hemolytic disease of the newborn [HDFN] and hemolytic transfusion reaction [HTR]. The hybrid Rhesus box that was created after RH gene deletion, was known as a mechanism of the Rh-negative phenotype. Hybrid marker identification is used to confirm the deletion of the RHD gene and to determine zygosity. This study aims to detect this marker in Rh-negative and weak D phenotype blood donors of the southeast of Iran.

Materials and Methods: The molecular analysis of the hybrid Rhesus box was performed on the 200 Rh-negative blood donors in Sistan and Baluchestan province, southeast Iran. The presence of alleles responsible for the D variants was assessed by DNA sequencing in 26 weak D phenotype donors.

Results: Of the 200 Rh-negative blood samples, 198 samples were homozygous (99%), and two samples were heterozygous (1%). Heterozygous samples had RHD*01N.73 allele and the RHD*01N.18 allele. Of the 26 samples with weak D phenotype, 16 partial DLO (61%), 4 partial DBT1 (15.3%), 2 partial DV type 2 (7.7%), 1 weak D type 1, 1 weak D type 4.2.3, 1weak D type 105 and 1 RHD (S103P) (4%) were determined.

Conclusion: Since RHD gene deletion is the main mechanism of the Rh-negativity in Sistan and Baluchestan provinces, a hybrid Rhesus box marker can be used in resolving RhD typing discrepancies by RHD genotyping methods.

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

INTRODUCTION

The alloimmunization following blood transfusion can be life-threatening. The Rh alloantibodies are one of the most common causes contributing to alloimmunization. This study aimed to evaluate the rate and causes of alloimmunization and to determine the Rh phenotypes and genotypes among sickle cell disease (SCD) and sickle thalassemia (Sβ).

MATERIALS AND METHODS

Our study included 104 SCD and Sβ patients referring to Baghaei 2 Hospital of Ahvaz in 2019 using a non-random simple sampling method. The blood samples were collected for Rh phenotypes, alloantibody screening and identification, and molecular tests. The SSP-PCR and RFLP methods with the Pst 1 enzyme were used.

RESULTS

The alloimmunization rate was 9.6% and 13.2% based on immunohematological tests and medical records, respectively. The main alloantibodies (90%) were anti-Rh, and 40% of the patients had multiple alloantibodies. A significant correlation was found between gender and alloimmunization. The phenotypes of DCce (37.5%), DCcEe (24%), Dce (20.2%), and dce (5.8%) and genotypes of R1r (25%), R1R2 (20.2%), R1R1 (18.3%), and R1R0 (10.6%) were the most prevalent. The R1R2 was a frequent genotype in Sβ.

CONCLUSION

R0r' and R1R0 genotypes were limited to our population in Iran. Due to the differences in RH genotypes between our population and others, the blood transfusion from other ethnicities increased our total alloimmunization rate.

Hemolytic disease of the fetus and newborn caused by anti-Hr0 in a 27-year-old female with Dc- phenotype: A case report

Anti-Hr₀ (Anti-Rh17) is a rare immune Immunoglobulin G (IgG) to high-frequency Rh antigens that may cause severe and often fatal Hemolytic disease of the fetus and newborn (HDFN) in D--, Dc- and DC^w- mothers who have been exposed to red cells of the common Rh phenotype by transfusion or pregnancy. Several pregnant women have been affected by this antibody leading to perinatal death. Therefore, immediate and effective management of these cases is of great importance. We report a case of HDFN in a 27-year-old (G5, P3, L1), woman with Rh Dc- phenotype managed successfully using intravenous immunoglobulin (IVIg) and simple transfusions.

RHD genotyping of serological weak D phenotypes in the Iranian blood donors and patients

BACKGROUND

Most prevalent weak D types in the Caucasians molecularly defined weak D types 1, 2 or 3 and can be managed safely as RhD-positive, conserving limited supplies of RhD-negative RBCs. Therefore, identification of RHD alleles prevalence in each population could improve the policies related to accuracy of RhD typing. The aim of this study was to determine the frequency of RHD variant alleles among donors and patients for the first time in Iran.

MATERIALS AND METHODS

RHD genotyping was performed on 100 blood donor and patient samples with weak D phenotype. PCR-SSP and DNA sequencing were used to identify the RHD alleles.

RESULTS

Molecular analysis showed only 15 samples were RHD*weak D 1(n = 13) and RHD*weak D 3(n = 2), and no cases of RHD*weak D 2 were detected. RHD*weak 15 (n = 43) was determined as the most prevalent D variants in our population and the other weak D types follows: RHD*weak 4, 5, 80 and one case of each one: RHD*weak 8, 11, 14, 100 and 105. Partial D variants also was identified in 18 samples as follows: RHD*partial DLO, DBT1, DV2, DHK and DAU-1.

CONCLUSION

The results of this study highlight the specific pattern of RHD status in the Iranian population. The weak D types 15 was the most common weak D type in the Iranian population. However, the screening for weak D types 1, 2 and 3 with 15 % frequency is also necessary for accurate RhD typing and developing clinical strategy of blood transfusion in weak D patients.