Development of a new screening method for faster kinship analyses in mass disasters: a proof of concept study.

Kinship analysis in forensics is based on the calculation of the respective kinship indices. However, this calculation is only possible when the subject under identification has been associated with a particular population, whose allele frequency data is available for the particular set of STR markers used in the forensic practices. In the case of mass disasters, where a large number of individuals are to be identified, gathering the population frequency data and calculating the kinship indices can be an intricate process which requires a lot of time and huge resources. The new method of allele matching cut off score (AMCOS) developed in this study is based on the allele sharing approach. This approach simply refers to the number of shared alleles (1 or 2) between the two individuals; also known as identical by state (IBS) alleles which might have been inherited from a recent common ancestor in which the alleles are identical by descendent (IBD). In case of mass disasters, this method can be used to narrow down the number of pairs (dead and alive) to be matched for kinship without using the allele frequency data. The results obtained from this method could further be confirmed by LR based method, which uses the allele frequency data of the respective population of the pairs being tested for kinship. AMCOS method has been tested for its sensitivity, specificity and various other statistical parameters and has shown promising values for the same in various types of kinship analyses. This ascertains the authenticity and potential use of this method in forensic practice but only after its validation in a larger sample size. AMCOS method has been tested on siblings and grandparent-grandchildren by using autosomal and X-STR markers both, as the reference samples from the parents cannot always be available for the identification. The present study also compared the results shown by the autosomal and X-STR markers in siblings and grandparent-grandchildren identification, thereby suggesting the use of better set of markers on the basis of obtained values of various statistical parameters.

Genetic diversity of X-STR markers in Jat Sikh population of Punjab, India and its comparison with other 39 global populations.

BACKGROUND: The Jat Sikh population is the largest endogamous group of Punjab, a state in north-west India, and has not yet been explored for genetic polymorphism based on X-STR genetic markers. In India, which is the second most populous country in the world, only two population studies based on X-STR markers have been reported so far. AIM: To explore the genetic diversity of 12 X chromosomal STR genetic markers in the Jat Sikh population of Punjab and expand the X-STR polymorphism database. SUBJECTS AND METHODS: In this study, a total of 200 Jat Sikh individuals (100 males and 100 females) residing in Punjab were investigated for 12 X-STR markers using the Investigator Argus X-12 QS Kit. RESULTS: The highest power of discrimination (PD) in females (PDf) and males (PDm) was observed to be 0.965 (DXS10135) and 0.929 (DXS10135 and DXS10148), respectively. DXS10135 was found to be the most polymorphic and discriminating locus among all the studied loci in both males and females with highest values of power of discrimination (PD) and polymorphic information content (PIC) as well. CONCLUSION: Overall, the studied markers of the Argus 12 X-STR kit provide high polymorphic information which may prove to be an important tool in resolving issues such as missing person identification, incest, immigration disputes, kinship analysis and genealogical studies. The dataset obtained from this study will add to the present database of X-STRs.

The genomic ancestry of Jat Sikh population from Northwest India inferred from 15 autosomal STR markers using capillary electrophoresis.

BACKGROUND: Autosomal STR typing using capillary electrophoresis is a reliable method for establishing parentage and for deciphering genomic ancestry. AIM: This study was planned to show the genetic diversity of the Jat Sikh population, which is a widespread community of the Punjab region, and to assess its genetic relationship with existing Indian populations. SUBJECTS AND METHODS: Blood samples of unrelated healthy individuals of the Jat Sikhs (n = 123) were used in this study. Fifteen autosomal STR markers along with the sex determination genetic marker Amelogenin were amplified using AmpFlSTR®Identifiler® Plus kit, and genetic analyser 3100 was used for genotyping. RESULTS: A total of 246 alleles were observed with allele frequencies ranging from 0.004 to 0.447. The heterozygosity ranged from 0.659 to 0.886, and all studied loci were in Hardy-Weinberg Equilibrium (HWE). Fibrinogen A alpha (Aα) chain (FGA) was found to be the most polymorphic and also the most discriminating locus in the studied population. Neighbor-joining (NJ) tree, principal component analysis (PCA) plot, and Nei's Distance matrix revealed genetic affinity with the previously reported Jatt Sikh (Punjab) population and showed the outlier nature of this population compared with other Indian populations. CONCLUSION: The data generated by this study enhance the database of Indian populations to be used in civil and forensic cases and also in other population-based genetic studies.