Genetic diversity of nine STRs in two northwest Iberian populations: Galicia and northern Portugal

The genotyping of two population samples from Galicia and northern Portugal was performed for nine STR loci using a single multiplex reaction with the AmpF/STR Profiler Plus PCR amplification kit which coamplifies the systems D3S1358, vWA, FGA, D8S1179, D21S11, D18S51, D5S818, D13S317, D7S820 and th e X-Y homologous gene amelogenin. Allele frequencies for these nine tetranu cleotide repeat markers were calculated and no significant differences were observed when comparing these two populations. Conformity with Hardy-Weinb erg equilibrium proportions was good for all systems in both samples. The c ombined power of exclusion was 99.981% and 99.980% in Galicia and northern Portugal, respectively and the combined power of discrimination was greater than 99.999%. Segregation analysis of all loci detected two incompatibilit ies, one in D3S1358 (out of 112 meioses) and another in D7S820 (out of 104 meioses). Both could be explained by single-step mutations. In general co-a mplification was good except for some relatively degraded samples in which poor amplification was observed for the largest STRs. Nevertheless the syst em is technically robust even when small amounts of template DNA are used a nd in addition is highly informative and time-saving. However, caution shou ld be taken in the interpretation of profiles in degraded samples and the a pparently high mutation rate of D3S1358 and D7S820 should also be kept in m ind.