ACKR1 gene polymorphisms in Bombay blood group (O_h) individuals of Indian origin

ACKR1 blood group genes exhibit a high degree of polymorphisms with varying allele distribution seen among different populations and ethnic groups. The study aimed to genotype ACKR1 antigens and to establish FY allele frequency among the individuals with the Bombay (Oh) blood group phenotype.

ACKR1 phenotype and genotype frequencies were estimated on 160 individuals typed as Oh and were compared with 100 non-oh blood donors from Mumbai, India by molecularly genotyping via PCR-RFLP.

The allelic and genotypic frequency of T(-67)C polymorphism showed the dominance of T allele and TT genotype [OR= 3.26 (0.59-17.99)] in both the study groups. The ACKR1 null (Fya-b-) phenotype was not found in the tested group. While the genotypic combination among the Oh group individuals was FYA/FYB (45.3 %), FYA/FYA (42.7 %), and FYB/FYB (12 %), in the non-Oh group donors, it was observed as FYA/FYB (53.3 %), FYA/FYA (39.1 %), and FYB/FYB (7.6 %). The haplotype TGGGC occurred in 38.4 % of the Oh group, but in non-Oh donors, it was found to be 50.9 % [OR = 1.820 (1.196-2.771)], and the difference was statistically significant (p = 0.005). Similarly, the TGGGT haplotype was found at a frequency of 12.7 % in non-Oh donors and 27.1 % in Oh group [OR= 0.411 (0.234-0.722)] (p = 0.001).

This study shows the prevalence of ACKR1 gene polymorphisms, including weak ACKR1 antigens in Oh individuals with a high frequency of haplotype TGGGC. The present study demonstrated for the first time the genotypes FyBweak, FyAweak and Fy Aweak/FyBESon RBC membranes in Indian subjects with Oh phenotype.