Calculation of likelihood ratio y/x in diagnosis of paternity using computer methods.

A new computational method using a Monte Carlo technique is described for the calculation of plausibility of paternity in blood group systems. In this study gene frequencies of a blood group system are simulated by the range of the seven digit random numbers. By using a Monte Carlo method, four random numbers are generated and converted into paternal and maternal genotypes. Then the genotype of the child is determined according to the law of inheritance, and finally genotypes of the father, mother and child are converted into phenotypes. Repeating this process more than one hundred thousand times, the phenotypic frequencies of child-mother-father combinations (trio) and the likelihood ratio of paternity in any blood group system are calculated for all phenotypic combinations of the trios. This method is much easier than methods reported previously, and is sufficiently accurate.