Effects of Reference Population and Number of STR Markers on Positive Evidence in Paternity Testing

Three sets of commonly used autosomal short tandem repeat (STR) markers (containing 15, 10 and 9 markers) and 14 databases from populations belonging to Africa, America, Asia and Europe were used to investigate how the selection of the population database and the number of considered markers would influence the statistical evidence that is usually produced to favour paternity. The study was based on a sample of 100 randomly chosen Finnish paternity trios collected during paternity testing case work and without any exclusion after use of 15 STR markers. Paternity Index, Probability of Paternity, Typical Paternity Index and Probability of Exclusion were computed and descriptive statistics were provided separately for trios (mother, child and putative father) and duos (obtained from trios but not considering the genetic information of the mother). This was done for all combinations of markers and databases. In trio cases the differences between results obtained are not statistically significant. However, especially in duo cases the use of 15 STR markers is recommended.