Establishment of paternity testing system using microsatellite markers in Chinese Holstein

To estimate the efficiency of microsatellite markers in paternity testing among Chinese Holstein, 30 microsatellite loci were used to differentiate 330 Chinese Holstein genotypes, according to the calculation of the allele frequency, number of alleles, effective number of alleles, genetic heterozygosity, polymorphic information content （PIC）, and the exclusion probability in this cattle population. The results demonstrated that the exclusion probability ranged from 0.620 in locus BM1818 to 0.265 in locus INRA005 with the average of 0.472 and 11 microsatellite markers exceeding 0.5. The combined exclusion probability of nine microsatellite markers was over 0.99. The result showed that paternity testing of Chinese Holstein was basically resolved using the nine microsatellite markers selected.

A Paternity Testing Case Using FFPE Tissue

Formalin-fixed and paraffin-embedded(FFPE)tissues provide a wealth of pathological information crucial for clinical and forensic examinations.Formalin induces robust complexes between DNA and proteins,impacting DNA extraction and complicating short tandem repeat(STR)typing for personal identification and paternity testing.Here,we present a case of paternity testing involving one FFPE tissue and one blood specimen.We compared four DNA extraction methods and analyzed the obtained products from the most successful approach.To ensure robust statistical support,we used a combination of three STR kits for the analysis.This case demonstrates the viability of using multiple kits in tandem for STR profiling of FFPE tissues.

Mutation Analysis of STR Locus on 23 Autosomes in Hainan Population

[Objective] To analyze the mutation signature and regularity of STR locus on 23 autosomes in paternity testing cases in Hainan. [Methods] A total of 2715 paternity testing cases accepted by the Forensic Medical Identification Centre of our hospital from 2017 to 2020 derived from counties and cities in Hainan Province were collected, the cases containing gene mutations were selected, the mutation rate and details of each locus were counted, and the mutation regu-larity of 23 STR loci was analyzed. [Results] Of the 2715 cases identified as “support”, 1487 were triplet cases and 1640 were dyad cases, totaling 4614 meioses;There were 50 gene mutation events (including 17 triplet mutations and 33 dyad mutations), with an average mutation rate of 0.0047% and a cumulative mutation rate of 1.0837%. A total of 19 of the 23 STR loci were mutated, with a mutation rate of 0.1301% at the D12S391 locus and 0.0217% at five loci, TPOX, D1S1656, D2S441, D22S1045, and PentaD, while no muta-tion events were found at four loci, D19S433, TH01, D13S317, and D7S820. Of the 50 mutation events, 47 were one-step mutations, 1 was two-step, and 2 were three-step. There were 35 paternal mutations (13 triplets and 22 dyads), 6 maternal mutations (4 triplets and 2 dyads), and 9 indeterminate pater-nal/maternal mutations, with a paternal to maternal mutation ratio of 5.83:1. [Conclusion] The mutation rate of D12S391 locus is the highest, and the muta-tion rate of TPOX, D1S1656, D2S441, D22S1045 and PentaD loci is the lowest in Hainan population, and paternal mutations are more than maternal muta-tions. In the paternity test, if 1 - 3 STR loci do not conform to the genetic law, especially when the mutant locus is homozygous or the next of kin is identi-fied, it is necessary to use other kits to review and increase the number of loci or use the second-generation sequencing technology to confirm, carefully de-termine the mutation and ensure the accuracy of the identification conclusion.

Investigation on the genetic-inconsistent paternity cases using the MiSeq FGx system

Mutations might challenge the paternity index calculation in forensic identification.While many studies have focussed on the autosomal short tandem repeats(A-STR),the mutation status of sex chromosomes and single nucleotide polymorphism(SNP)remain blank.Next generation sequencing(NGS),known as high throughput and large sequence polymorphism,is a promising tool for forensic genetics.To describe the mutation landscapes in the paternity cases with genetic inconsistencies,a total of 63 parentage confirmed paternity cases contained at least one mismatched locus have been collected.The mutations were subsequently evaluated using Verogen’s MPSForenSeqTM DNASignature Kit and a microsatellite instability(MSI)detection kit.The result showed 98.41%(62/63)of the cases had no additional autosomal mutations even when the number of A-STRs increased to 27.As for the sex chromosomes,about 11.11%(7/63)of the cases exhibited either X-STR or Y-STR mutations.D2S1338,FGAand Penta Ewere the most frequent altered STRs,which suggested they might be the mutation hotspots.In addition,a male with sex chromosome abnormality was observed accidently,whose genotype might be 47,XXY,rather than MSI.Nearly 56.90%of the STR loci possessed isoalleles,which might result in higher STR polymorphisms.No Mendelian incompatibility was detected among the SNP markers,which indicated that SNP was a more reliable genetic marker in the genetic-inconsistent paternity cases.