A nomenclature for sequence-based forensic DNA analysis

Forensic DNA analysis of casework samples using massively parallel sequencing (MPS) technology requires a system of nomenclature for uniquely labeling sequence-based alleles and artifacts. The DNA Commission of the ISFG has published considerations concerning a nomenclature format that addresses the requirement for unique labeling of sequences. Nomenclatures based on this format can be used in databasing, or communicating sequence types, but the format is lengthy for software interfaces. The sequence identifier (SID) nomenclature addresses this gap by generating short labels able to uniquely identify all sequences (allelic and artifactual) in single-source or casework profiles. Sequences in casework profiles can be uniquely labeled with only two or three SID characters, making the format compact. SID labels can be used in algorithms for identifying and filtering artifacts, and for expressing associations between artifacts and their likely parent alleles. The nomenclature is suitable for use in downstream mixture analysis by any software able to accept character values rather than numeral values. The SID nomenclature is described, and its ability to discriminate sequence-based alleles and artifacts is demonstrated, and its applicability to forensic mixture analysis is demonstrated.