Large-scale pedigree analysis highlights rapidly mutating Y-chromosomal short tandem repeats for differentiating patrilineal relatives and predicting their degrees of consanguinity

Advancements in differentiation between sperm cells and epithelial cells for efficient forensic DNA analysis in sexual assault cases

Most of the sexual assault casework samples are of mixed sources. Forensic DNA laboratories are always in the requirement of a precise technique for the efficient separation of sperm and non-sperm DNA from mixed samples. Since the introduction of the differential extraction technique in 1985, it has seen significant advancements in the form of either chemicals used or modification of incubation times. Several automated and semi-automated techniques have also adopted the fundamentals of conventional differential extraction techniques. However, lengthy incubation, several manual steps, and carryover over non-sperm material in sperm fraction are some of the major limitations of this technique. Advanced cell separation techniques have shown huge promise in separating sperm cells from a mixture based on their size, shape, composition, and membrane structure and antigens present on sperm membranes. Such advanced techniques such as DEParray, ADE, FACS, LCM, HOT and their respective pros and cons have been discussed in this article. As current-day forensic techniques should be as per the line of Olympic slogan i.e., faster, higher, stronger, the advanced cell separation techniques show a huge potential to be implemented in the casework samples.

Male Pedigree Toolbox: A Versatile Software for Y-STR Data Analyses

Y-chromosomal short tandem repeats (Y-STRs) are widely used in forensic, genealogical, and population genetics. With the recent increase in the number of rapidly mutating (RM) Y-STRs, an unprecedented level of male differentiation can be achieved, widening and improving the applications of Y-STRs in various fields, including forensics. The growing complexity of Y-STR data increases the need for automated data analyses, but dedicated software tools are scarce. To address this, we present the Male Pedigree Toolbox (MPT), a software tool for the automated analysis of Y-STR data in the context of patrilineal genealogical relationships. The MPT can estimate mutation rates and male relative differentiation rates from input Y-STR pedigree data. It can aid in determining ancestral haplotypes within a pedigree and visualize the genetic variation within pedigrees in all branches of family trees. Additionally, it can provide probabilistic classifications using machine learning, helping to establish or prove the structure of the pedigree and the level of relatedness between males, even for closely related individuals with highly similar haplotypes. The tool is flexible and easy to use and can be adjusted to any set of Y-STR markers by modifying the intuitive input file formats. We introduce the MPT software tool v1.0 and make it publicly available with the goal of encouraging and supporting forensic, genealogical, and other geneticists in utilizing the full potential of Y-STRs for both research purposes and practical applications, including criminal casework.

Genetic polymorphism of 27 Y-STR loci in Kazakh populations from Central Kazakhstan

BACKGROUND

The haplotypes from Northern, Southern, Eastern, and Western Kazakhstan, analysed for 27 Y-STR loci, have been contributed to the Y-Chromosome STR Haplotype Reference Database, while the genetic profile of Central Kazakhstan remains inadequately explored.

AIM

To investigate the genetic diversity of 27 Y-STR loci in the Kazakh populations from Central Kazakhstan.

SUBJECTS AND METHODS

A total of 112 unrelated Central Kazakh males were genotyped via the Yfiler Plus kit. Data analysis yielded haplotype and allele frequencies, and forensic parameters. Genetic distances were graphically represented by a multidimensional scaling plot, with genetic linkages further elucidated through Nei's distance dendrograms and Median-joining networks.

RESULTS

A total of 102 haplotypes were detected, of which 96 were unique. The haplotype diversity and discrimination capacity were 0.997 and 0.91, respectively. Central Kazakhstan displays a unique cluster in analyses, underscoring its distinct Y-chromosome diversity compared to other Kazakh regions. The analysis of the Naiman tribe, predominantly residing in Central, Southern and Eastern Kazakhstan, revealed three genetic clusters of distinct haplogroups associated with their clans.

CONCLUSIONS

The identified haplotypes will enhance the existing reference database for Y-chromosomal studies in Kazakhstan, offering a robust tool for future research in population genetics, forensic science and genetic genealogy.