A computer calculation of probability of monozygosity for twins.

A general algorithm is described to calculate the probability of monozygosity of concordant twins on the basis of blood type tests. Frequencies of all combinations of twins and parents are created with the aid of a translational matrix which facilitates conversion of genotypes to phenotypes automatically. The method of calculation is explained by taking Rh system in Germany as an example. The probability of monozygosity is calculated for all combinations of twin and/or father and/or mother. Effects of parental phenotypes on the efficiency in the diagnosis are analyzed quantitatively. Applicability of this method to other calculations concerning genetics is also discussed.