Microhaplotypes (MHs) have gained prominence in forensic genetics as highly informative markers that combine the low mutation rates and short amplicon sizes of Single Nucleotide Polymorphisms (SNPs) with the enhanced allelic diversity typical of multiallelic systems. Next generation sequencing (NGS) permits the recovery of full sequence information from targeted SNP assays, enabling the identification of additional variation within SNP amplicons. These variants can be used to define novel MHs without modifying existing laboratory protocols.
In this study, we characterize MHs derived from complete SNP amplicons included in the Illumina ForenSeq™ DNA Signature Prep Kit using the latest Universal Analysis Software (UAS v2.7.0). Genetic variation was assessed in two independent datasets: (i) high-coverage (30×) whole-genome sequencing data from the 1000 Genomes Project generated by the New York Genome Center (NYGC), and (ii) a regional reference dataset from the Valencian Community (Spain), composed of unrelated individuals participating as family donors in an ongoing Spanish Civil War victim identification program.
For each MH, we evaluated allelic diversity, population genetic parameters, and performed simulations to assess their utility in human identification scenarios. Full amplicon sequence analysis revealed substantial intra amplicon variation capable of defining informative MHs across multiple loci. These MHs displayed an increased effective number of alleles and heterozygosity, as well as higher discriminatory power compared to the underlying biallelic SNPs.
Our findings demonstrate that analysing the complete ForenSeq SNP amplicon provides additional informative value for forensic applications without requiring additional laboratory work or increasing costs.