Substitution mutation induced migration anomaly of a D10S2325 allele on capillary electrophoresis.

Microvariants of short tandem repeat (STR) have been reported for different commercially available multiplex STR systems. Sequence length variations caused by variant mechanisms were the central cause of these abnormal phenomena. Here, we reported a novel electrophoretic mobility of the variant allele 13 of D10S2325 in the Investigator HDplex(TM) Kit, which was induced by a special sequence structure containing a poly-G tract (ttg ggg ggg) as a result of only one single base substitution in the flanking regions of the core repeat structure. This migration anomaly can pose a potential risk of wrong designation of some off-ladder alleles in STR loci. Furthermore, population genetic data of the Investigator HDplex(TM) Kit in the Chinese Han population are also reported.