Estimation of efficiency of blood group in comparison with DNA typing tests in disputed paternity

Blood grouping test is a tool to resolve the problems of disputed paternity. Therefore, we decided to calculate its chance of exclusion depending on the phenotype data on seven blood groups (ABO, Rh, MNSs, kell, kidd, Lutheran and P1) in south and central parts of Iran. Moreover, red cells tests and full STRs results for paternity disputes were compared. The main aim of this research is to evaluate the efficiency of blood grouping test in comparison with DNA typing. Blood Samples were obtained from 174 unrelated individuals belonging to the south and central parts of Iran. Then, DNA Typing for the 12 Loci and blood testing were performed simultaneously. The chance of exclusion in each system of ABH, Rh, MNSs, kell, kidd, Lutheran and P1 is 19.5%, 29.77%, 22.28%, 3.64%, 9.77%, 3.47% and 4.5%, respectively. From 82 paternity tested, in 42 cases no mismatch was observed for STRs that supported paternity. In 40 cases that alleged father was excluded by DNA Typing, in 22 (55%) cases, there are no mismatches in blood groups. 18 (45%) cases showed mismatches at one or more antigenic systems. Overall, two alleged farther were excluded just by red cell typing regarding to criteria of non-paternity; remaining cases needed DNA Typing. This study shawed that considering the probability of excluding of all mentioned blood groups systems, 64.83% of them can not be used to prove paterninty. On the other hand, owing to low efficiency in exclusion, high cost, laboratory error rate and availability of DNA Typing, we recommended that routine red cell tests for court cases should be limited to AB and Rh [CcDEe] systems.: