Long allele designations at D2S1338 and D19S433 loci as influenced by various multiplex STR kits.

European forensic laboratories are replacing the STR multiplex kits with the new generation 16/17 STR kits. This study examines the influence of the new generation kits and the new Applied Biosystems 3500xL Genetic Analyzer on the designation of long D2S1338 and D19S433 off-ladder alleles. Different allele calls were obtained using the new NGM™ (Applied Biosystems) and PowerPlex(®) ESI™ (Promega) kits compared with AmpFℓSTR(®) SGM Plus™ kit (Applied Biosystems). Sequence analysis was used to determine accurate allele designation. The new multiplex kits and the 3500xL Genetic Analyzer improved accuracy of long allele designations. DNA databases worldwide include countless profiles obtained by previous kits. Discrepancies between the new and former technologies may cause failure to detect hits. Discordance is expected due to primer sequence differences between various kits. An additional discordance, occurring in long alleles, independent of primer sequence is reported in this study.