Mutation Rates of STR Systems in Danes

Danish paternity cases in the period 1999 to 2005 were investigated regarding mutation rates in STR loci. STR-typing was performed by the Applied Biosystems AmplfStr Profiler Plus kit in the period 1999 to early 2005, hereafter named the PP9, and by Applied Biosystems AmplfStr Identifier kit for the rest of 2005, hereafter named the IDFL. All cases with one to four genetic inconsistencies were manually inspected by two forensic geneticists and statistically analyzed by five statisticians. We found no significant effect of kits and no interaction of kits and STRA loci, but differences in mutation rates on different STR loci. In the cases where mutations had occured, we found no interaction between kits, STRA loci or sexes. However, we found differences in the mutation rates between the sexes, meaning that the differences in male and female mutation rates can be assumed constant over STR loci and kits. Sex and STR locus specific mutation rates were estimated with 95% confidence limits by the method of Clopper and Pearson (1934).