X-STR Allele and Linkage Haplogroup Frequencies in the Lebanese Population and the Potential of X-STR Polymorphism in Forensic Casework

Authors: Obeid M#, El Andari A#, Outhman H and Mansour I*

DOI: 10.23880/ijfsc-16000145

Volume 3, Issue 3

Abstract

When autosomal STR profiling fails to supply satisfactory outcome in human identification and/or in forensic casework, scientists may use Y-STR and/or X-STR profiling. However, representative X-STR allele and haplogroup frequencies should be established in the studied population for proper use of X-STR profiles. In this study, 507 non-related males and females representative of the Lebanese population as to the religious and geographic distributions were tested to establish the X-STR allele frequencies. 500 non-related males were tested to establish the X-STR haplogroup frequencies. DNA was amplified using Investigator™ Argus X-12 multiplex PCR system (Qiagen). Results were analyzed using in-house software (FIMS), Arlequin v3.5 software, MEGASTAT software and an online software: http://www.chrx-str.org. System DXS10135 showed to be the most informative while system DXS8378 was the least informative. The combined discrimination power (CDP) in both males and females was equal to one. The combined mean exclusion chance (CMEC) was 0.999999548 in duo paternity cases and 0.999999998 in trio paternity cases. The haplotype assessment showed that all 500 tested haplotypes were unique. The haplogroups assessment using the Investigator™ Argus X-12 kit, which determines four haplogroups named haplogroup one, two, three and four, showed high number of haplogroups 329, 194, 185 and 257 respectively, which reflects a relatively high level of X-STR polymorphism in the Lebanese population compared to Y-STR. The most frequent linkage group showed a relatively low frequency of 0.048. However, when compared to the most frequent linkage group in the German population (0.037), it showed a higher frequency, Results indicate high potentials in the field of forensic science and mandate the use of X-STR analysis for complex cases based on their ability to complement autosomal and Y-STR analysis.

Keywords: X-STR, Allele Frequency; Linkage Group; Lebanese Population

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