Single Nucleotide Polymorphisms Associated with Alcohol-Induced Flushing Syndrome in Korean Population / 대한법의학회지

Alcohol-induced flushing syndrome is one of the alcohol hypersensitivity reactions commonly found among Asian population. This study was designed to find markers that can predict this particular propensity among Korean population and to assess the applicability of this finding to build a prediction model as forensic DNA phenotyping tool to operate in practical forensic cases. Five hundred seventy unrelated Koreans were genotyped using microfluidic technology with 24 possible candidate single nucleotide polymorphism (SNP) markers. Of the 24 candidate SNPs, four markers, rs671, rs2074356, rs4646776, and rs10849915, on chromosome 12 showed statistically significant association with P-values ranging from 1.39×10⁻¹⁴ to 0.004988 among our subjects. All four markers show relatively high specificity values, ranging from 0.804651 to 0.972093, presenting their capabilities as differential SNPs that can distinguish a person with or without alcohol-induced flushing syndrome. Maneuvering these candidate SNPs as well as finding additional potential markers through future studies will help building an appropriate prediction model for Koreans that can be used as supplementary tool for individual identification.

Single Nucleotide Polymorphisms Associated with Alcohol-Induced Flushing Syndrome in Korean Population / 대한법의학회지

Alcohol-induced flushing syndrome is one of the alcohol hypersensitivity reactions commonly found among Asian population. This study was designed to find markers that can predict this particular propensity among Korean population and to assess the applicability of this finding to build a prediction model as forensic DNA phenotyping tool to operate in practical forensic cases. Five hundred seventy unrelated Koreans were genotyped using microfluidic technology with 24 possible candidate single nucleotide polymorphism (SNP) markers. Of the 24 candidate SNPs, four markers, rs671, rs2074356, rs4646776, and rs10849915, on chromosome 12 showed statistically significant association with P-values ranging from 1.39×10⁻¹⁴ to 0.004988 among our subjects. All four markers show relatively high specificity values, ranging from 0.804651 to 0.972093, presenting their capabilities as differential SNPs that can distinguish a person with or without alcohol-induced flushing syndrome. Maneuvering these candidate SNPs as well as finding additional potential markers through future studies will help building an appropriate prediction model for Koreans that can be used as supplementary tool for individual identification.

Detection of Innate and Artificial Mitochondrial DNA Heteroplasmy by Massively Parallel Sequencing: Considerations for Analysis

BACKGROUND: Mitochondrial heteroplasmy, the co-existence of different mitochondrial polymorphisms within an individual, has various forensic and clinical implications. But there is still no guideline on the application of massively parallel sequencing (MPS) in heteroplasmy detection. We present here some critical issues that should be considered in heteroplasmy studies using MPS. METHODS: Among five samples with known innate heteroplasmies, two pairs of mixture were generated for artificial heteroplasmies with target minor allele frequencies (MAFs) ranging from 50% to 1%. Each sample was amplified by two-amplicon method and sequenced by Ion Torrent system. The outcomes of two different analysis tools, Torrent Suite Variant Caller (TVC) and mtDNA-Server (mDS), were compared. RESULTS: All the innate heteroplasmies were detected correctly by both analysis tools. Average MAFs of artificial heteroplasmies correlated well to the target values. The detection rates were almost 90% for high-level heteroplasmies, but decreased for low-level heteroplasmies. TVC generally showed lower detection rates than mDS, which seems to be due to their own computation algorithms which drop out some reference-dominant heteroplasmies. Meanwhile, mDS reported several unintended low-level heteroplasmies which were suggested as nuclear mitochondrial DNA sequences. The average coverage depth of each sample placed on the same chip showed considerable variation. The increase of coverage depth had no effect on the detection rates. CONCLUSION: In addition to the general accuracy of the MPS application on detecting heteroplasmy, our study indicates that the understanding of the nature of mitochondrial DNA and analysis algorithm would be crucial for appropriate interpretation of MPS results.

Forensic DNA Phenotyping: A Review in Korean Perspective / 대한법의학회지

Forensic DNA phenotyping (FDP) using human externally visible characteristics (EVCs) is an emerging new technique that allows for the prediction of phenotypic traits of a person of interest using relevant sets of genetic markers. This technique predicts not only physical appearances, but also the behavioral characteristics as well as biogeographical information, serving as a powerful supplementary tool to narrow down the investigative pool in various forensic cases. Over the past few years, many countries, Europe and America being at the forefront, have conducted significant research to identify related markers for predicting pigmentation traits such as eye, hair, and skin color. Furthermore, some commercial platforms are now available for practical use in forensic cases. Korea and other Asian countries have also dedicated remarkable research to identify relevant markers to utilize FDP in forensic investigations. However, a slightly different approach is needed because Asians have limited phenotypic variations than Western populations. Thus, medically irrelevant and simple propensity traits such as smoking and alcohol consumption could be used to compensate for the limited phenotypic variations. This article is intended to inform readers about the progress and worldwide trends in EVC research, as well as the whereabouts and future prospects of FDP-related research in Korea. Although various legal and ethical disputes must be resolved beforehand, employing an FDP system can certainly be a powerful complementary tool for providing additional clues in forensic investigations.

Entire Mitochondrial DNA Sequencing on Massively Parallel Sequencing for the Korean Population

Mitochondrial DNA (mtDNA) genome analysis has been a potent tool in forensic practice as well as in the understanding of human phylogeny in the maternal lineage. The traditional mtDNA analysis is focused on the control region, but the introduction of massive parallel sequencing (MPS) has made the typing of the entire mtDNA genome (mtGenome) more accessible for routine analysis. The complete mtDNA information can provide large amounts of novel genetic data for diverse populations as well as improved discrimination power for identification. The genetic diversity of the mtDNA sequence in different ethnic populations has been revealed through MPS analysis, but the Korean population not only has limited MPS data for the entire mtGenome, the existing data is mainly focused on the control region. In this study, the complete mtGenome data for 186 Koreans, obtained using Ion Torrent Personal Genome Machine (PGM) technology and retrieved from rather common mtDNA haplogroups based on the control region sequence, are described. The results showed that 24 haplogroups, determined with hypervariable regions only, branched into 47 subhaplogroups, and point heteroplasmy was more frequent in the coding regions. In addition, sequence variations in the coding regions observed in this study were compared with those presented in other reports on different populations, and there were similar features observed in the sequence variants for the predominant haplogroups among East Asian populations, such as Haplogroup D and macrohaplogroups M9, G, and D. This study is expected to be the trigger for the development of Korean specific mtGenome data followed by numerous future studies.

Factors Affecting DNA Yields from Serum and Plasma Samples Used for Personal Identification Testing / 대한법의학회지

Serum or plasma is free of cellular components. As DNA is in the nucleus or mitochondria of a cell, it can be presumed that serum/plasma is DNA free. However, there are cases wherein serum/plasma is the only resource available for identification analysis, yet no sufficient data are available regarding whether reliable DNA testing can be applied to such cases, and what the influencing factors are when testing is a valid course of action. The aim of this study is to illustrate the factors that can be used in the genetic testing of serum/plasma when identifying an individual. The results showed that the concentration of serum DNA significantly increased over time in 4℃ storage, and the DNA yields from samples stored in heparin tubes were overall higher than from samples stored in ethylenediaminetetraacetic acid tubes. We observed that the concentration of DNA in serum successfully matched 100% to the short tandem repeat data of blood DNA.

Forensic Application of Age Estimation Using Signal Joint T-Cell Receptor Excision Circles in Human Lymphoid Tissues / 대한법의학회지

The declining tendency of signal joint T-cell receptor excision circles (sjTRECs) in peripheral blood is known to be age-dependent, and their quantification in blood or bloodstains has recently been introduced as a tool for age estimation. Lymphoid tissues such as the thymus and spleen represent potential candidates for age estimation because they undergo age-related structural and functional changes. In the present study, the correlation between age and sjTREC levels in human lymphoid tissues, namely the thymus, spleen, and blood, obtained from autopsy cases were investigated, with the goal of establishing a reliable age estimation model. Results showed negative regression curves with coefficient values of r=-0.410, r=-0.611, and r=-0.584 for thymus, spleen, and blood, respectively. In addition, this model was testing using thymus samples from the torsos of dismembered bodies from two real forensic cases, and results showed the predicted ages to be close to the actual ages of the victims. Further study will be required to improve accuracy and reduce estimation error, particularly within the lower age range. Nonetheless, these results suggest that quantification of sjTRECs in not only blood but also in other lymphoid tissues could be a useful tool for age estimation in forensic cases.

Looking Back at Our 5-Year Experience of Paternity Testing: A Summary / 대한법의학회지

We have been testing familial relationships based on short tandem repeats (STRs) in families who requested it either voluntarily or by order of the court. Here, we present a summary of our 5-year experience of autosomal STR-based paternity tests. A total of 1,431 individuals from 588 cases were tested, including 878 pairs of either of the parent, and a child. Among these 588 cases, genetic information about the other parent was available only for 135 cases. Five hundred eighteen pairs were concluded to be parent-child relations, for which the median paternity index (PI) was 72,826, and the median decimal logarithm was 4.860. Autosomal mutation was observed in nine pairs (1.74%), and the pairs harbored only one mismatched locus among the 15 standard loci (D8S1179, D21S11, D7S820, CSF1PO, D3S1358, TH01, D13S317, D16S539, D2S1338, D19S433, vWA, TPOX, D18S51, D5S818, and FGA). The number of mismatched loci did not increase even after additional loci were included in the study. The observed mutation rates were D13S317 (0.193%), D18S51 (0.193%), D19S433 (0.193%), FGA (0.193%), vWA (0.386%), Penta D (0.387%), and Penta E (0.193%). There were 14 pairs with two mismatched loci, which we excluded through additional tests on either autosomal or X chromosomal STRs, and mitochondrial sequencing. Although PI is useful for determining parent-child relation, it provides indirect information; it is an interpretation of the test results that is based on probability. Additional genotyping on sex chromosome and mitochondrial DNA, or participation of other family members might be beneficial for a reliable conclusion.

Mixture Patterned Short Tandem Repeat Profile in a Perimortem Transfused Patient / 대한법의학회지

Recently, it has been reported that transfused patients can generate admixture-like genetic profiles. As genetic material of the donor can survive for a reasonable time after transfusion, the recipient's genomic DNA is likely to have a mixture pattern. An autopsy case of a man transfused perimortem generated a mixture patterned short tandem repeat profile. Notably, the patient was transfused mostly with nuclear-deficient cells, limiting the donor genetic material available for the recipient. As a result, mixture-like patterns were observed consistently, regardless of change in input DNA content; the sample DNA content, which was serially diluted, ranged from 1 ng to 0.0625 ng. The distributions of foreign peaks appeared to be irreproducible, showing stochastic behaviors throughout the genotyped results. This study suggests that a cautious approach is required when genotyping of a patient who has undergone recent transfusion. One must consider the possibility of obtaining a mixture patterned profile in such patients, and therefore, choose parenchymal organs or tissues for reliable results.

Limitation of Regular Autosomal STR Testing for Paternity within an Isolated Population / 대한법의학회지

In order to determine paternity by genetic testing, the Paternity Index (PI) and probability of paternity are calculated using likelihood ratio method. However, when it is necessary, additional testing can be performed to validate the genetic relationship. This research demonstrates autosomal short tandem repeat (STR) results of Jeju Island population in order to determine genetic relationship. Two notable cases showed that despite the acceptable PI value obtained from STR testing, average of 12 mismatches were found in total of 169 autosomal single nucleotide polymorphism typing. Such cases imply that cautious statistical approach is necessary when determining genetic relationship, especially within an isolated population group. Moreover, this would suggest that a further research and investigation are needed in order to understand the population structure of Korea.