Sequenced allelic ladders and population genetics of a new STR multiplex system

The advent of PCR technology and use of short tandem repeat (STR) loci impr oves throughput and reduces costs whilst a high level of discrimination can be achieved. A new system, comprising seven STRs, was developed to complim ent the existing systems. This paper describes the preparation of allelic l adders of the most commonly observed alleles of a new STR multiplex system (third generation; TGM multiplex); all alleles have been sequenced. Meioses studies estimated a mutation rate of 0-0.4% across loci. Statistical indep endence was investigated by employing exact tests; chi (2)-tests and excess homozygosity tests. The results demonstrated that the allele proportions d o not differ from those expected and that there was no consequential depend ence between loci. The discriminating power of the system was examined usin g 295 Caucasian, 140 Afro-Caribbean and 212 Asian unrelated samples, and wa s found to be approximately 1 in 50 million, 1 in 85 million and 1 in 20 mi llion for each of these groups, respectively. (C) 2001 Elsevier Science Ire land Ltd. All rights reserved.