STRNaming: Generating simple, informative names for sequenced STR alleles in a standardised and automated manner

Abstract

The introduction of Massively Parallel Sequencing in the forensic domain has exposed the need for comprehensive nomenclature of sequenced Short Tandem Repeat (STR) alleles. In general, three strategies are at hand: 1) the full sequence mapped to the human genome reference sequence, which ensures exact data exchange; 2) shortened, human-readable formats for forensic reporting and data presentation and 3) very short codes that enable compact figures and tables but do not convey any sequence information. Here, we describe an algorithm of the second type: STRNaming, which generates human-readable names for sequenced STR alleles. STRNaming is guided by a reference sequence at each locus and then functions independently to automatically assign a unique, sequence-descriptive name that also includes the capillary electrophoresis allele number. STRNaming settings were established based on preferences that were surveyed internationally in the forensic community. These settings ensure that a small change in the sequence corresponds to a small change in the allele name, which is helpful for recognising for instance stutter products. Sequence variants outside of the repeat units are indicated as simple variant calls. Since the STR name is sequence-descriptive, the sequence can be traced back from the allele name. Because STRNaming is fully guided by an assignable reference sequence, no central coordination or configuration is required and the method will work for any STR locus, be it autosomal, Y-, X-chromosomal in current or future use. The algorithm is publicly available online and offline.

Keywords: Allele names; Forensic science; MPS; NGS; Nomenclature; STR.