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Sequence-based allelic variations and frequencies for 22 autosomal STR loci in the Lebanese population

NCJ Number
Forensic Science International: Genetics Volume: 65 Dated: 2023
Date Published

This article describes the authors’ research with the following objectives: to sequence DNA extracts from 195 Lebanese individuals; investigate genetic distance and population structure of the Lebanese individuals in relation to four U.S. populations; describe, with their respective repeat and flanking polymorphisms, the full allelic sequences at 22 autosomal STR loci; calculate allelic frequencies for the sequence variants; and assess forensic informativeness metrics of the allelic sequences.


This is the first study that characterizes the sequence-based allelic variations of 22 autosomal Short Tandem Repeat (aSTR) loci in a population dataset collected from Lebanon. Genomic DNA extracts from 195 unrelated Lebanese individuals were amplified with PowerSeq 46GY System Prototype. Targeted amplicons were subjected to DNA library preparation and sequenced on the Verogen MiSeq FGx Sequencing System. Raw FASTQ data files were processed by STRait Razor v3. Sequence strings were annotated according to the considerations of the DNA Commission of the International Society for Forensic Genetics (ISFG) and tabulated herein with their respective allelic frequencies and GeneBank accession and version numbers. The sequenced Lebanese dataset resulted in 429 distinct allelic sequences as compared to the 236 alleles identified by length only. The authors note their observations and discovery of 25 novel aSTR allelic sequences across 12 loci. For a concordance check, the length-based allelic calls derived from the full sequences were compared to those genotyped using capillary electrophoresis (CE) methods. Population genetic parameters relevant to the evaluation of forensic DNA evidence were assessed for the sequence-based data and compared to the parameters generated from the length-based information. Using the sequence-based data, Analysis of MOlecular VAriance (AMOVA), genetic distances, and population genetic structure were evaluated for 1231 individuals sampled from the Lebanese and four U.S. populations (African American, Asian, Caucasian, and Hispanic). The authors tabulated and visualized the results in a population tree, multidimensional scaling scatter plots, and bar plots, and suggest that the sequence-based database for the Lebanese population may benefit extending NGS applicability to casework or paternity testing and assessing the strength of evidence for NGS-STR profiles. The described novel sequence variants at certain loci can further help in the effort to characterize the sequence diversity of STR markers from different populations around the world. Publisher Abstract Provided

Date Published: January 1, 2023