PHENOTYPIC AND GENOTYPIC FREQUENCIES OF ABO AND RH(D) BLOOD GROUPS AMONG STUDENTS IN MODJO SECONDARY SCHOOL, OROMIA, ETHIOPIA

Blood is the red viscous fluid that circulates around the body supplying O2 and nutritive substances to the tissues and returns CO2 to lungs and metabolites to the kidneys, for regulation of body temperature, and distributes hormones.The frequency of the blood groups varies worldwide and may not be found in equal numbers even among the same ethnic groups.The aim of this study was to find out the distribution of ABO and Rh (D) blood groups,the allele and genotype frequencies among students attending Modjo Secondary school in East Shoa Zone Oromia, Ethiopia. The study was conductedfrom March –July 2023 in a laboratory in the study area. Blood samples were taken from 403 (N = 403) volunteer students from fingerpricks and blood groups were determined on open slide by haemagglutination method using commercially available anti-sera A, B, and D. Descriptive statistics such as percentage and frequency of blood phenotypeswas used.The genotypic and allelic frequencies of the blood groups were calculated from the observed phenotypic frequency under the assumption of Hardy–Weinberg equilibrium. In the ABO blood grouping system, type O was the most dominant (38.9%) followed by A (29.3%), B (24.8%) and AB (the least or (6.95%), in the pattern O > A > B > AB. Most of the students were found to be Rh+ (88.3%) and the reastwere Rh- 11.7%. Concerning within the combined ABO/Rh D blood groups, O+ was the most dominant (141), A+ (100), B+ (90) and AB+ (24) and A- was also the most frequentamong the Rh negatives. These occur as A-(4.47%),O-(3.97%), B- (2.48%) and AB- (0.99%) among Rh-negative students. The allelic frequencies of O (r), A (p) and B (q), D and d were 0.624, 0.202, 0.174, 0.6536, and 0.3464, respectively. Genotypic frequency of IOIO was the most (0.389) frequent while that of IBIB was the least (0.030) while DD and dd were 0.433 and 0.117 respectively.The observed and expected frequencies of individuals having ABO and Rh blood were significantly different in both blood systems (for ABO, X2= 0.008185with df =3; p < 0.05 and X2 for Rh(D) =0.00006455847, df = 1; p < 0.05 this occurred in the order of IO> IA> IB.). The present study gives vital information concerning the management of blood bank and transfusion services in the community. Its importantduring medical diagnosis and emergency and accidental health disorder especially for donating blood. This study is the first document in the study area and evidence for other person who wants making research on phenotypic and genotypic frequency of ABO and Rh (D) blood group system.