Frequencies of ABO and Rh (D) groups vary throughout the world due to ethnic diversity. The distribution may also vary across country areas due to different ethnic groups. Oman is a genetically admixed population country consisting of African, Caucasian and Asian ancestries. Due to frequencies variation throughout the world and lack of study in Oman, this propelled us to determine the phenotypes and estimate the genetic variability of ABO and Rh (D) blood groups in the Omani population. This retrospective study concerning ABO and Rh (D) blood groups of a small section of the Omani population was undertaken between January 2017 and December 2017. The data were reviewed and calculations performed to determine ABO and Rh (D) phenotypes, allele frequencies and genotypes estimation. The results were compared with other populations. 

Three thousand four hundred and sixteen (3416) blood donors' data from Armed Forces Hospital blood bank were collected. Overall distribution of ABO group in Omanis is; group O (50.47%), group A (24.06%), group B (21.63%) and group AB (3.83%), whereas distribution of Rh (D) positive and Rh (D) negative is 91.65% and 8.35% respectively. Allelic frequency of A, B, O, D and d is 0.15, 0.14, 0.71 0.71 and 0.29 respectively. Genotype frequencies recorded as (AA = 0.0225, AO = 0.213, BB = 0.0196, BO = 0.1988, AB = 0.042, OO = 0.5041, DD = 0.5057, Dd = 0.411 and dd = 0.0833). The commonest ABO blood group in Omanis is O group while the AB group is the rarest with the sequence O > A > B > AB. The recorded frequencies appear to be intermediate between some other countries and different to some other Middle East regions including Arabs.

Keywords: ABO/Rh blood group, ABO allele, ABO genes, RHD genes, allele frequency, Omani population.

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Mujtaba Allawati

Dept. of Medical Laboratory Science, Oman Collage of Health Sciences, Sultanate of Oman