Rapidly mutating Y-STR analyses of compromised forensic samples

Investigation of a DNA Profiling Method Using Only Cementum More Than 70 Years After Death

Short tandem repeat (STR) typing is widely used not only for blood relationship identification but also for the personal identification of unidentified bodies. However, DNA is susceptible to the effects of environmental factors, consequently leading to reduced DNA yields. Therefore, to maximize the DNA yield required for identification, teeth are generally completely pulverized during DNA extraction. However, this renders subsequent testing after DNA profiling impossible. In this study, we investigated the utility of DNA profiling using only the cementum from teeth that had been left outdoors for long postmortem intervals. We analyzed 90 molars (fresh teeth) that were extracted within six months at a dental clinic and 90 molars (stale teeth) exposed outdoors for over 70 years, and following cementum extraction, the accuracy of STR profiling, optimal site for cementum collection, and minimum amount of cementum required for STR profiling were determined. The results demonstrated that the profiling accuracy of DNA extracted from cementum was comparable to that of DNA from dental pulp and dentin. Furthermore, the collection of cementum from either near the cervical line or from the root apex areas did not show significant differences in DNA profiling accuracy, indicating that securing at least 5 mg of cementum was sufficient to ensure precise DNA profiling. These findings suggest that DNA profiling using only cementum is viable even in teeth that have been subjected to a long postmortem interval.

Genetic polymorphisms of 44 Y chromosomal genetic markers in the Inner Mongolia Han population and its genetic relationship analysis with other reference populations

Y chromosomal genetic markers in the non-recombining region are commonly used for human evolution research, familial searching, and forensic male differentiation since they strictly follow paternal inheritance. Y chromosomal short tandem repeats (Y-STRs) possess extraordinarily advantages in forensic applications because of their high polymorphisms and special genetic pattern. Here, we assessed the genetic diversities of 41 Y-STRs and three Y chromosomal insertion/deletion (Y-InDels) loci in the Chinese Inner Mongolia Han population; besides, genetic differentiation analyses among the studied Han population and other previously reported populations were conducted based on 27 same Y-STRs. Totally, 425 alleles were observed in 324 Inner Mongolia Han individuals for these Y-markers. Gene diversities of these Y-markers distributed from 0.0306 to 0.9634. The haplotype diversity and discriminatory capacity of these Y-markers in the Inner Mongolia Han population were 0.9999 and 0.98457, respectively. Haplotype resolution comparisons of different Y-marker groups in the studied Han population revealed that higher haplotype resolution could be achieved for these 44 Y-markers. Population genetic analyses of the Inner Mongolia Han population and other reference populations demonstrated that the studied Han population had relatively closer genetic affinities with Northern Han Chinese populations than Southern Han and other minority groups. To sum up, these 44 Y-markers can be utilized as a valuable tool for male differentiation in the Inner Mongolia Han population.

Male individualization using 12 rapidly mutating Y-STRs in Araein ethnic group and shared paternal lineage of Pakistani population

A multiplex assay has been developed with newly designed primer sets comprising high mutation rate 12 RM Y-STR markers (DYS570, DYF399S1, DYS547, DYS612, DYF387S1, DYS449, DYS576, DYS5626, DYF403S1 (a + b), DYS627, DYS526, and DYF404S1). Rapidly mutating Y-STRs were evaluated in 167 male individuals among 97 were unrelated from Araein ethnic group and 70 belonged to shared paternal lineage including 20 pairs of father-son and 15 pairs of brother-brother relationship collected from Punjabi population of Pakistan. Forensic competency parameters were implemented for each marker and exceptionally significant results found wherein polymorphism information content (PIC) was in range of 0.7494 (DYS576) to 0.8994 (DYS627). Samples were also analyzed with Y-filer kit for comparison and marked differentiations observed. Haplotype discrimination capacity was 100% as no haplotype shared among all the unrelated individuals of same ethnic group as compared to 17 Y-filer loci (78%). While in closely related males, discrimination capacity was 96.4% with haplotype diversity value of 0.98. Resulted high mutation rate 1 × 10^-2 to 7.14 × 10^-2 as compared to Y-filer (1 × 10^-4 to 1 × 10^-3) manifested the power of RM Y-STRs for considering absolute individualization of interrelated and unrelated male individuals. However, multiplex assay would be useful for male discrimination in mixed DNA specimen, azoospermic males, and multiple male DNA contributors in sexual assault cases and mass disasters victim's identification as well as anthropological studies.

Genetic analysis of 39 Y-STR loci in a Han population from Henan province, central China

A total of 39 Y-chromosomal short tandem repeat (Y-STR) loci included in the advanced commercial six-dye multiplex system (AGCU Database Y30 kit) and a custom-designed four-dye multiplex system were investigated in 259 unrelated healthy Chinese males residing in Henan Province, central China. The haplotype diversity (HD) values were 0.99997 and 1.0000 for the six and four fluorescent-multiplex amplification systems, respectively. The discrimination capacity (DC) values were 0.9961 and 1.0000, respectively. When the 39 Y-STR loci were considered, 259 unique haplotypes were obtained in Henan Han individuals with both the haplotype diversity and discrimination capacity being 1.000. The gene diversity (GD) of 39 Y-STR loci in the studied group ranged from 0.3956 (DYS588) to 0.9990 (DYF403S1). Population comparisons between the Henan Han and 24 reference groups were performed. Both multidimensional scaling plots and phylogenetic analysis demonstrated that significant genetic differences existed between Henan Han and reference ethnic minorities of China, particularly the Tibetan, Uighur, and Mongolian populations. Moreover, the results indicated that 39 Y-STRs included in the two fluorescent-multiplex amplification systems are highly polymorphic and informative in the studied populations and can be employed as complementary tools for forensic application and human genetics research.