Ju Yeon Jung

Forensic genetic study of 29 Y-STRs in Korean population

In this study, we compared two recently released commercial Y-chromosomal short tandem repeat (Y-STR) kits: the PowerPlex Y23 System (PPY23) and Yfiler® Plus PCR amplification kit (YPlus). We performed validation studies, including sensitivity, tolerance to PCR inhibitors, and mixture analysis, and a population genetics study using 306 unrelated South Korean males. PPY23 and YPlus showed similar sensitivity, but PPY23 showed higher tolerance to humic acid than YPlus. Furthermore, the detection rate of unique minor alleles called from male/male mixtures was higher for PPY23 than for YPlus. Comparing the newly added loci, the mean values of gene diversity for PPY23 and YPlus were 0.6715 and 0.8158, respectively. The discrimination capacity in the 306 unrelated South Korean males for PPY23 was 0.9837, and that for YPlus was 0.9935. These results will inform the selection of suitable Y-STR kits based on the purpose of forensic DNA analysis.

Evaluation of forensic genetic parameters of 12 STR loci in the Korean population using the InvestigatorⓇ HDplex kit

We genotyped and calculated the forensic parameters of 10 non-CODIS loci and 2 CODIS loci of 990 Korean individuals using the InvestigatorⓇ HDplex kit. No significant deviations from Hardy–Weinberg equilibrium (after Bonferroni correction for multiple testing) or genetic linkage disequilibrium were observed. The calculated matching probability and power of discrimination ranged from 0.0080 to 0.2014, and 0.7986 to 0.9920, respectively. We conclude that the markers of the kit are highly informative corroborative tools for forensic DNA analysis.

Simple and rapid identification of saliva by detection of oral streptococci using direct polymerase chain reaction combined with an immunochromatographic strip

In this paper, we describe the development of a novel method to detect oral bacteria by combining direct polymerase chain reaction (direct PCR) with an immunochromatographic strip (ICS), enabling the identification of saliva in forensic samples. Direct PCR was first used to directly amplify specific oral bacterial sequences (from Streptococcus sanguinis and Streptococcus salivarius) from swab samples, circumventing the need for tedious sample preparation steps such as cell lysis and DNA extraction and purification. The resultant amplicons were then colorimetrically detected on an ICS, a much more convenient, cost-effective, and user-friendly detection method than those currently available, thereby allowing the presence or absence of the target oral bacteria to be determined with the naked eye. Moreover, the entire analysis process was performed rapidly and with ease using this combination of direct PCR amplification from swab samples and ICS-based amplicon detection. This method successfully detected S. sanguinis and S. salivarius in most of the saliva swab samples tested, and returned negative results using blood, semen, urine, and vaginal fluid swab samples. Furthermore, S. sanguinis and S. salivarius were detected in a large number of mock forensic samples using this technique, which suggests that direct PCR and ICS-based detection of oral bacteria is sufficient to demonstrate the presence of saliva. Thus, we believe that the proposed method could be very useful for the identification of saliva in forensic applications.

Performance of MiniPCR TM mini8, a portable thermal cycler

Abstract: A small and inexpensive thermal cycler (PCR machine), known as the MiniPCR TM Mini8 ThermalCycler (Amplyus, Cambridge, MA, USA), was developed. In this study, the performance of this PCR machinewas compared with the GeneAmp ® PCR system 9700 (Applied Biosystems) using four autosomal short tandemrepeat (STR) kits, a Y-chromosome STR kit, and a mitochondrial DNA HV1/HV2 sequence analysis. Thesensitivity and stochastic effects of the STR multiplex kits and the quality of the DNA sequence analysis weresimilar between the two PCR machines. The MiniPCR TM Mini8 Thermal Cycler could be used for analysesat forensic DNA laboratories and crime scenes. The cost of the PCR is so economical that school laboratoriesand individuals could use the machines.요약: 최근 손안에 들어올 정도로 크기가 작아 범죄현장 등에서 사용이 가능하며, 다른 일반적인 장비들에 비해 가격이 1/10이하로 저렴하여 TM누구나 사용할 수 있는 MiniPCR mini8 Thermal Cycler (Amplyus,Cambridge, MA, USA)가 개발되었다. 본 연구에서는 DNA감식에 일반적으로 사용되고 네 가지 종류의 상염색체 STR 다중증폭 키트들과 한 종류의 Y 염색체 STR 증폭키트, 그리고 미토콘드리아 DNA HV1/HV2의 염기서열 분석법을 사용하여 MiniPCR

Sensitivity study of the Yfiler ® PLUS PCR Amplification Kit in forensic casework samples

A variety of Y-STR analysis kits have been developed and used in the forensic field. Prior to the forensic application of a new kit, laboratory validation and sensitivity tests are essential processes in selecting suitable alternatives and for assuring that standard operating procedures are followed. In this paper, we have performed a sensitivity study of a new commercial kit, the Yfiler ® PLUS PCR Amplification Kit (Yfiler plus kit, released in 2014) by comparing it with the AmpF/STR ® Yfiler TM PCR Amplification Kit (Yfiler kit, released in 2004). The Yfiler plus kit includes the 17 Y-STR loci of the Yfiler kit and has been supplemented with 10 new Y-STR loci. First, we analyzed the sensitivity difference between the two kits using commercial control DNA 2800M and 007. In addition, we compared the detection rate between the two kits from the 16 selected forensic casework samples of less than 0.5 ng concentrations. The results show that the sensitivity and detection rate of the Yfiler plus kit are higher than the corresponding rates of the Yfiler kit. In addition, we were able to obtain more Y-STR profiles with the use of the new kit. Thus, we suggest that Yfiler plus kit is a more effective forensic tool to detect Y-STR profiles from forensic casework samples of low concentrations. 요약 : 법과학 분야에서 다양한 Y-STR 분석 키트가 개발되어 사용되고 있고, 새로운 키트의 법과학적 적용에 앞서 DNA 감정에 적절한 분석 키트들의 선정과 표준작업절차서의 작성을 위해 실험실 내의 내 부적 유효성 검증 및 민감도 시험은 필수적인 과정이다. 본 논문에서는 새로운 상업용 키트인 Yfiler ®

Rapid oral bacteria detection based on real-time PCR for the forensic identification of saliva

This study developed a new method for forensic saliva identification using three oral bacteria, Streptococcus salivarius, Streptococcus sanguinis, and Neisseria subflava, combined with a real-time polymerase chain reaction (RT-PCR) system we called OB mRT-PCR. Analytical sensitivity results showed that the target bacteria were amplified at 102–107 copies/reaction, and analytical specificity was assessed using 24 other viruses, bacteria, and protozoa. To evaluate the OB mRT-PCR kit for forensic applications, saliva from 140 Korean individuals was tested, and at least two target bacteria were detected in all the samples. Additional studies on non-saliva samples demonstrated the specificity of the kit. Comparison of the kit with two conventional saliva test methods, the SALIgAE and RSID-Saliva assays, indicated that it was more sensitive and applicable to saliva samples in long-term storage (up to 14 weeks). Additionally, through amplification of mock forensic items and old DNA samples (isolated without lysis of the bacterial cells, regardless of their Gram-positivity), we found that the kit was applicable to not only saliva swabs, but also DNA samples. We suggest that this simple RT-PCR-based experimental method is feasible for rapid on-site analysis, and we expect this kit to be useful for saliva detection in old forensic DNA samples.

A validation study of DNA methylation-based age prediction using semen in forensic casework samples

Previously, an age-predictive method based on DNA-methylation patterns in semen was developed, using three CpG sites (cg06304190 in the TTC7B gene, cg12837463, and cg06979108 in the NOX4 gene). Before considering the routine use of a new method in forensics, validation studies such as concordance and sensitivity tests are essential for obtaining expanded and more reliable forensic information. Here, we evaluated a previously described age-predictive method for semen for routine forensic use. Concordance testing showed a high correlation between the predicted and chronological age, with a mean absolute deviation from the chronological age of 4.8 years. Sensitivity testing suggested that age prediction with reliable accuracy and consistency was possible with >5 ng of bisulfite-converted DNA. We also confirmed the applicability of the age-predictive method in forensic casework, using forensic samples. Thus, the proposed method could serve as a very valuable forensics tool for accurate age prediction with semen samples.

Enhanced sensitivity of CpG island search and primer design based on predicted CpG island position

DNA methylation has important biological roles, such as gene expression regulation, as well as practical applications in forensics, such as in body fluid identification and age estimation. DNA methylation often occurs in the CpG site, and methylation within the CpG islands affects various cellular functions and is related to tissue-specific identification. Several programs have been developed to identify CpG islands; however, the size, location, and number of predicted CpG islands are not identical due to different search algorithms. In addition, they only provide structural information for predicted CpG islands without experimental information, such as primer design. We developed an analysis pipeline package, CpGPNP, to integrate CpG island prediction and primer design. CpGPNP predicts CpG islands more accurately and sensitively than other programs, and designs primers easily based on the predicted CpG island locations. The primer design function included standard, bisulfite, and methylation-specific PCR to identify the methylation of particular CpG sites. In this study, we performed CpG island prediction on all chromosomes and compared CpG island search performance of CpGPNP with other CpG island prediction programs. In addition, we compared the position of primers designed for a specific region within the predicted CpG island using other bisulfite PCR primer programs. The primers designed by CpGPNP were used to experimentally verify the amplification of the target region of markers for body fluid identification and age estimation. CpGPNP is freely available at http://forensicdna.kr/cpgpnp/.