Probability of paternity exclusion in different mother-child genotype combinations

Paternity testing 3: exclusion probabilities

Blood typing with several blood systems is used in many countries to determine paternity or nonpaternity with respect to an alleged father. Various probabilities are usually presented, in particular: the conditional probability of excluding a random man as father given a particular mother-child phenotype combination, and the expected (unconditional) exclusion probability for all mother-child combinations can be calculated for a given blood system. Because these probabilities are of general interest in paternity studies, explicit formulae for the unconditional probabilities have been derived for some of the systems. Algorithms suitable for a microcomputer are given here for finding the exclusion probabilities for any system. These algorithms avoid the need for developing new formulae whenever a new system is introduced or a current system is extended through the addition of further alleles.

Unequal mitotic sister chromatid exchange and different length of Y chromosomes

There is wide variation in the length of the Y chromosome. In the same individual the length varies continuously and is normally distributed. We describe a boy with borderline mental retardation, gross and fine motor coordination difficulty, muscle rigidity, ptosis, clinodactyly, and a Y chromosome of different lengths in two separate cell populations. The most probable explanation of the cytogenetic finding is a mitotic unequal sister chromatid exchange of the Y chromosome.