Development and validation of a new 18 X‐STR typing assay for forensic applications

Abstract

With a unique inheritance pattern compared to autosomal short tandem repeats (A‐STRs), X chromosomal STRs (X‐STRs) have special usage in forensic relationship testing. In this study, we designed a multiplex amplification system (named TYPER‐X19 multiplex assay) consisting of 18 STR loci spreading from 7.837 to 149.460 Mb on the X chromosomes (DXS9895, DXS8378, DXS9902, DXS6810, DXS7132, DXS10079, DXS6789, DXS7424, DXS101, DXS6797, DXS7133, DXS6804, GATA165B12, DXS10103, HPRTB, GATA31E08, DXS8377, and DXS7423), and the amelogenin. PCR primers were marked with four kinds of fluorophores including FAM, HEX, TAMRA, and ROX. The multiplex system was optimized and tested for precision, concordance, reproducibility, sensitivity, stability, DNA mixture, and species specificity according to the conventional validation guidelines. The results indicated that the system was accurate, reliable, and sensitive enough, and was suitable for common forensic case‐type samples. In the population genetic study, a total of 148 alleles were detected at the 18 X‐STR loci in 398 Southern Han Chinese. Relatively high combined power of discrimination in male (PDm), power of discrimination in female (PDf), mean paternity exclusion chance in trios (MECtrio), and mean paternity exclusion chance in duos (MECDuo) by Desmarais were detected, and HPRTB‐DXS10103 was in linkage disequilibrium. The results suggested that the TYPER‐X19 multiplex assay was suitable for forensic applications.

Genetic Polymorphisms and Forensic Parameters of Thirteen X-Chromosome Markers in the Iraqi Kurdish Population

“…In addition, DNA samples from Iraqi Arab males in Baghdad City were only examined. Other studies have reported developing and validating new X-STR assays utilizing different combinations of the X-STR loci to obtain genetic information from particular populations and to investigate the forensically relevant parameters [31][32][33][34][35]. The present study found that the highest and lowest GD and PIC in the Kurdish population were at the GATA172D05 and DXS10164 loci, respectively.…”

Recent advances in forensic biology and forensic DNA typing: INTERPOL review 2019–2022

“…One example of the forensic application of X-chromosome markers include use in relationship testing cases involving suspicion of incest or paternity without a maternal sample for comparison [ 503 ]. Four new X-STR multiplex assays were described along with validation studies including a 19plex [ 504 ], a 16plex [ 505 ], another 19plex – the Microreader 19X Direct ID System [ 506 ], and an 18plex named TYPER-X19 multiplex assay [ 507 ]. A collaborative study examined paternal and maternal mutations in X-STR markers [ 508 ].…”

Forensic Applications of Markers Present on the X Chromosome

“…The Investigator Argus X-12 kit was also used in this study, and 914 complete haplotypes were obtained for the markers included in the kit. Knowing the uniqueness provided by the X-STR markers, several research groups conducted studies to assess the population distribution of countries such as Brazil, Switzerland, Italy, India, Croatia, and countries on the African continent, among others [ 9 , 15 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 ]. Table 1 lists some population studies that explore X-STR markers, published in the last ten years.…”

“…In this sense, research groups focused on the development of amplification kits with a greater number of markers. Zhang et al [ 37 ] developed and validated the TYPER-X19 multiplex amplification system, consisting of 18 STR loci on the X chromosome (DXS9895, DXS8378, DXS9902, DXS6810, DXS7132, DXS10079, DXS6789, DXS7424, DXS101, DXS67683, DXS7, DXS7 GATA165B12, DXS10103, HPRTB, GATA31E08, DXS8377, and DXS7423) and amelogenin. It was possible to verify that the TYPER-X19 system was sensitive, reliable, and efficient for use in forensic approaches.…”