OBJECTIVES: To compare the effects of cell lysis method and magnetic beads method in forensic DNA identification and to explore these two methods in forensic DNA identification. METHODS: The genome DNA of THP-1 cells in different quantities was extracted by the cell lysis method and magnetic beads method, and the DNA content was quantified by real-time quantitative PCR. The cell lysis method and magnetic beads method were used to type the STR of human blood with different dilution ratios. RESULTS: When the numbers of THP-1 cell were 100, 400 and 800, the DNA content extracted by cell lysis method were (1.219±0.334), (5.081±0.335), (9.332±0.318) ng, respectively; and the DNA content extracted by magnetic beads method were (1.020±0.281), (3.634±0.482), (7.896±0.759) ng, respectively. When the numbers of THP-1 cells were 400 and 800, the DNA content extracted by the cell lysis method was higher than that by the magnetic beads method. The sensitivity of cell lysis method and magnetic beads method was similar in STR typing of human blood at different dilution ratios. Complete STR typing could be obtained at 100, 300 and 500-fold dilutions of blood samples, but could not be detected at 700-fold dilution. STR typing of undiluted human blood could not be detected by cell lysis method. CONCLUSIONS The cell lysis method is easy to operate and can retain template DNA to the maximum extend. It is expected to be suitable for trace blood evidence tests.
Humans ; Forensic Medicine ; DNA/genetics* ; Real-Time Polymerase Chain Reaction ; Magnetic Phenomena ; DNA Fingerprinting/methods* ; Microsatellite Repeats

With the improvement of DNA methylation detection techniques, studies on age-related methylation sites have found more age-specific ones across tissues, which improves the sensitivity and accuracy of age estimation. In addition, the establishment of various statistical models also provides a new direction for the age estimation of tissues from different sources. This review summarizes the related studies of age estimation based on DNA methylation from the aspects of detection technology, age-related cytosine phosphate guanine site and model selection in recent years.
DNA Methylation ; Forensic Genetics/methods* ; CpG Islands ; Forensic Medicine

Kinship testing is widely needed in forensic science practice. This paper reviews the definitions of common concepts, and summarizes the basic principles, advantages and disadvantages, and application scope of kinship analysis methods, including identity by state (IBS) method, likelihood ratio (LR) method, method of moment (MoM), and identity by descent (IBD) segment method. This paper also discusses the research hotspots of challenging kinship testing, complex kinship testing, forensic genetic genealogy analysis, and non-human biological samples.
DNA Fingerprinting ; Forensic Genetics/methods* ; Forensic Sciences ; Pedigree ; Humans

OBJECTIVES: To evaluate the forensic application value of an age estimation model based on DNA methylation in eastern Chinese Han population, and to provide a theoretical basis for exploring age estimation models suitable for different detection platforms. METHODS: According to the 6 age-related methylation sites in the published blood DNA methylation age estimation models of Chinese Han population, the DNA methylation level of 48 samples was detected by pyrosequencing and next-generation sequencing (NGS). After submitting DNA methylation levels to the age estimation model, the DNA methylation ages were predicted and compared with their real ages. RESULTS: The 6 DNA methylation sites in both detection techniques were age-related, with an R² of 0.85 and a median absolute deviation (MAD) of 4.81 years when using pyrosequencing；with an R² of 0.84 and MAD of 4.41 years when using NGS. CONCLUSIONS The blood DNA methylation age estimation model can be used under pyrosequencing and multi-purpose regional methylation enrichment sequencing technology based on NGS and it can accurately estimate the age.
Humans ; Aging/genetics* ; CpG Islands ; DNA Methylation ; East Asian People ; Forensic Genetics/methods*

OBJECTIVES: To establish the menstrual blood identification model based on Naïve Bayes and multivariate logistic regression methods by using specific mRNA markers in menstrual blood detection technology combined with statistical methods, and to quantitatively distinguish menstrual blood from other body fluids. METHODS: Body fluids including 86 menstrual blood, 48 peripheral blood, 48 vaginal secretions, 24 semen and 24 saliva samples were collected. RNA of the samples was extracted and cDNA was obtained by reverse transcription. Five menstrual blood-specific markers including members of the matrix metalloproteinase (MMP) family MMP3, MMP7, MMP11, progestogens associated endometrial protein (PAEP) and stanniocalcin-1 (STC1) were amplified and analyzed by electrophoresis. The results were analyzed by Naïve Bayes and multivariate logistic regression. RESULTS: The accuracy of the classification model constructed was 88.37% by Naïve Bayes and 91.86% by multivariate logistic regression. In non-menstrual blood samples, the distinguishing accuracy of peripheral blood, saliva and semen was generally higher than 90%, while the distinguishing accuracy of vaginal secretions was lower, which were 16.67% and 33.33%, respectively. CONCLUSIONS The mRNA detection technology combined with statistical methods can be used to establish a classification and discrimination model for menstrual blood, which can distignuish the menstrual blood and other body fluids, and quantitative description of analysis results, which has a certain application value in body fluid stain identification.
Female ; Humans ; RNA, Messenger/metabolism* ; Bayes Theorem ; Logistic Models ; Menstruation ; Body Fluids ; Saliva ; Semen ; Forensic Genetics/methods*

OBJECTIVES: To explore the feasibility of genetic marker detection of semen-specific coding region single nucleotide polymorphism (cSNP) based on SNaPshot technology in semen stains and mixed body fluid identification. METHODS: Genomic DNA (gDNA) and total RNA were extracted from 16 semen stains and 11 mixtures composed of semen and venous blood, and the total RNA was reverse transcribed into complementary DNA (cDNA). The cSNP genetic markers were screened on the validated semen-specific mRNA coding genes. The cSNP multiplex detection system based on SNaPshot technology was established, and samples were genotyped by capillary electrophoresis (CE). RESULTS: A multiplex detection system containing 5 semen-specific cSNPs was successfully established. In 16 semen samples, except the cSNP located in the TGM4 gene showed allele loss in cDNA detection results, the gDNA and cDNA typing results of other cSNPs were highly consistent. When detecting semen-venous blood mixtures, the results of cSNP typing detected were consistent with the genotype of semen donor and were not interfered by the genotype of venous blood donor. CONCLUSIONS The method of semen-specific cSNPs detection by SNaPshot technology method can be applied to the genotyping of semen (stains) and provide information for determining the origin of semen in mixed body fluids (stains).
Genetic Markers ; Semen ; Polymorphism, Single Nucleotide ; DNA, Complementary/genetics* ; Body Fluids ; RNA, Messenger/genetics* ; DNA ; Saliva ; Forensic Genetics/methods*

As an important anthropometric characteristic, human height not only contributes to the recognition of other anthropological characteristics and genetic risk factors, but also is an important part of forensic DNA phenotyping studies. Accurate estimation of height can provide more complete information about the phenotype of suspects and provide help to solve cases. In recent years, having benefited from the rapid development of molecular biological techniques and bioinformatics, height-related genetics research has made some progress. This paper describes the research progress of human height estimation from the genetic variation and the epigenetic inheritance perspectives and looks into the future research direction.
Humans ; Phenotype ; DNA/genetics* ; Molecular Biology ; Forensic Genetics/methods*

Due to the virtues of no stutter peaks, low rates of mutation, and short amplicon sizes, insertion/deletion (InDel) polymorphism is an indispensable tool for analyzing degraded DNA samples from crime scenes for human identifications (Wang et al., 2021). Herein, a self-developed panel of 43 InDel loci constructed previously by our group was utilized to evaluate the genetic diversities and explore the genetic background of the Han Chinese from Beijing (HCB) including 301 random healthy individuals. The lengths of amplicons at 43 InDel loci in this panel ranged from 87 to 199 bp, which indicated that the panel could be used as an effective tool to utilize highly degraded DNA samples for human identity testing. The loci in this panel were validated and performed well for forensic degraded DNA samples (Jin et al., 2021). The combined discrimination power (PD) and combined probability of exclusion (PE) values in this panel indicated that the 43 InDel loci could be used as the candidate markers in personal identification and parentage testing of HCB. In addition, population genetic relationships between the HCB and 26 reference populations from five continents based on 19 overlapped InDel loci were displayed by constructing a phylogenetic tree, principal component analysis (PCA), and population genetic structure analysis. The results illustrated that the HCB had closer genetic relationships with the Han populations from Chinese different regions.
Beijing ; China ; Forensic Genetics/methods* ; Gene Frequency ; Genetics, Population ; Humans ; INDEL Mutation ; Phylogeny

Diatom detection is an important method for identifying drowning and throwing corpses after death and inferring the drowning sites in forensic examination of corpses in water. In recent years,high-throughput sequencing technology has achieved rapid development and has been widely used in research related to diatom taxonomic investigations. This paper reviews the research status and prospects of high-throughput sequencing technology and its application in forensic diatom detection.
Cadaver ; Diatoms/genetics* ; Drowning/diagnosis* ; Forensic Pathology/methods* ; High-Throughput Nucleotide Sequencing ; Humans ; Lung ; Technology

In recent years, more and more forensic genetics laboratories have begun to apply massively parallel sequencing (MPS) technology, that is, next-generation sequencing (NGS) technology, to detect common forensic genetic markers, including short tandem repeat (STR), single nucleotide polymorphism (SNP), the control region or whole genome of mitochondrial DNA (mtDNA), as well as messenger RNA (mRNA), etc., for forensic practice, such as individual identification, kinship analysis, ancestry inference and body fluid identification. As the most widely used genetic marker in forensic genetics, STR is currently mainly detected by capillary electrophoresis (CE) platform. Compared with CE platform, MPS technology has the advantages of simultaneous detection of a large number of genetic markers, massively parallel detection of samples, the polymorphism of sequence detected by NGS makes STR have the advantages of higher resolution and system efficiency. However, MPS technology is expensive, there is no uniform standard so far, and there are problems such as how to integrate MPS-STR data with the existing CE-STR database. This review summarizes the current status of the application of MPS technology in the detection of STR genetic markers in forensic genetics, puts forward the main problems that need to be solved urgently, and prospects the application prospect of this technology in forensic genetics.
DNA Fingerprinting/methods* ; Forensic Genetics/methods* ; Genetic Markers ; High-Throughput Nucleotide Sequencing/methods* ; Microsatellite Repeats/genetics* ; Polymorphism, Single Nucleotide ; Sequence Analysis, DNA ; Technology