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

Background: The gene is one of the most complex blood group genes. The molecular background of the gene in RhD-negative and RhD-positive individuals varies within and among different populations. Knowing the molecular basis of the 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 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 gene was detected in all, indicating the zygosity status of the deletion allele. The gene was detected in 79% of the RhD-positive individuals, suggesting high frequencies of -negative haplotypes.

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