No abstract

Recently, the interest of the forensic community has been focused on new Y-chromosomal short tandem repeats (Y-STRs), termed Rapidly Mutating Y-STRs (RM-YSTRs), which is able to differentiate between close males belonging to the same paternal lineage due to their high mutation rates. In this study, we have estimated a mutation rate for 13 RM-YSTR in 85 pairs of male relatives in the population of Serbia. We analysed 74 fatherson pairs, and 11 twin pairs, to evaluate the capacity of distinguishing between male subjects within a single lineage. Each father-son couple was previously confirmed by autosomal STRs testing (AmpFℓSTR ® Identifiler Plus™ kit, Applied Biosystems) with paternity probability ≥99.99% and also confirmed monozygotic or dizygotic twins. Results showed that, in the 74 father-son pairs 23 mutations were detected of which 22 were onestep mutations and 1 was two-step mutation, while in the 11 twin pairs 1 mutation was observed in one dizygotic twin pair. Five father-son pairs were found to have mutations at two loci, while one pair at four loci. Overall, the most mutable markers were DYF399S1, DYF387S1, DYF403S1a and DYS612. Our findings are encouraging and concur with previous studies showing that by RM-YSTR typing the discrimination power of male relatives could be considerably increased in comparison to every YSTR markers commonly used in forensic genetics.

Y chromosome short tandem repeat polymorphisms (Y-STRs) are important in many areas of human genetics. Y chromosomal STRs, being normally utilized in the field of forensics, exhibit low haplotype diversity in consanguineous populations and fail to discriminate among male relatives from the same pedigree. Rapidly mutating Y-STRs (RM Y-STRs) have received much attention in the past decade. These 13 RM Y-STRs have high mutation rates (>10−2) and have considerably higher haplotype diversity and discrimination capacity than conventionally used Y-STRs, showing remarkable power when it comes to differentiation in paternal lineages in endogamous populations. Previously, we analyzed two to four generations of 99 pedigrees with 1568 pairs of men covering one to six meioses from all over Pakistan and 216 male relatives from 18 deep-rooted endogamous Sindhi pedigrees covering one to seven meioses. Here, we present 861 pairs of men from 62 endogamous pedigrees covering one to six meioses from the Punjabi population of Punjab, Pakistan. Mutations were frequently observed at DYF399 and DYF403, while no mutation was observed at DYS526a/b. The rate of differentiation ranged from 29.70% (first meiosis) to 80.95% (fifth meiosis), while overall (first to sixth meiosis) differentiation was 59.46%. Combining previously published data with newly generated data, the overall differentiation rate was 38.79% based on 5176 pairs of men related by 1–20 meioses, while Yfiler differentiation was 9.24% based on 3864 pairs. Using father–son pair data from the present and previous studies, we also provide updated RM Y-STR mutation rates.

FTA ® cards were developed for analysing reference samples such as blood or saliva and helping to store the sample for long term purposes as it kills the microorganisms that comes along with biological stains which can be potential inhibitors. The aim of this research is to optimize a reduced volume PCR amplification for STR analysis of reference blood samples. This approach will help to reduce the costs of DNA profiling using direct amplification multiplex assays. A total number of 130 blood samples from different individuals were collected on FTA ® cards. The reaction was optimized using half volume for amplification with Identifiler ® Direct and Globalfiler™ Express multiplex assays. The protocol was applied in a forensic laboratory and was able to reduce costs and account for variability of DNA amounts among reference samples.

This article details the development of a single multiplex system amplifying 26 rapidly mutating Y‐STR markers. A sequenced allelic ladder, constructed for calling alleles of all loci, is introduced. The multiplex system shows the ability to address the limitations of Y‐STRs commercial kits in differentiating closely related males. The multiplex performed well in the prevalidation tests and showed great potential to be used in forensic casework.