ALLELIC AND GENOTYPIC FREQUENCIES OF ABO AND Rh BLOOD GROUP AMONG STUDENTS ATTENDING TULU CHUKALA SECONDARY SCHOOL, ADULALA TOWN, EAST SHOA ZONE, OROMIA REGIONAL STATE,

The four blood types are known as A, B, AB, and O. Blood type A contains A antigen on the surface of red blood cells and B antibody on blood plasma. Type B blood contains the reverse combination. Serum of blood type AB contains neither antibody, but red cells in this type of blood contain both A and B substances. In type O blood, neither substance is present on the red cells, but the individual is capable of forming antibodies directed against red cells containing substance A nor B. Frequency distribution of ABO and Rh blood groups is helpful for ef ective management of blood banks and safe blood transfusion services. The prevalence of these blood groups varies worldwide and may not be found in equal numbers even among the same ethnic groups. The study aimed to determine ABO and Rh-D blood groups distribution frequencies among 422 students at Liban Chukala Secondary School from March to May 2022.Blood samples were taken from volunteer students by using commercially available anti-sera A, B, and Rh (D) from finger-pricks and blood groups were determined on open slide and blood types were determined by agglutination reaction test. The genotypic and allelic frequencies of the blood groups were calculated from the observed phenotypes under the assumption of Hardy–Weinberg equilibrium. In the ABO system, type O was the most prevalent (45%) followed by A (30.8%), B (19%) and AB the least (5.2%), in the pattern O > A > B > AB. Most of the students were found to be Rh+ (96.21%) and some students were found to be Rh- (3.79). The allelic frequencies of O (r), A (p) and B (q), D and d were 0.6707, 0.1999, 0.1294, 0.0.8053 and 0.1947, respectively. Genotypic frequency of IOIO was the most (0.45) frequent while that of IB IB was the least (0.0167) while DD and dd were 0.6485 and 0.038, respectively. The observed and expected frequencies of individuals having ABO and Rh blood were is significance between in both blood systems (goodness-of-fit χ 2 for ABO = 0.0025, df = 3 and χ 2 for Rh = 0.0001, df = 1; P < 0.05). In general this study provides information for Tulu Chukala Secondary School students to know their own blood type, because of the knowledge of blood group distribution is very important for