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.

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.

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.

A Case of Molecular Analysis of XX Male Syndrome / 대한법의학회지

Sex typing may become the start point in investigations that are usually performed through amelogenin typing. In cases involving genotype-phenotype discrepancy, amelogenin typing could yield misleading results. The rare XX male syndrome is characterized by a phenotypic male with a 46, XX female karyotype. In this point, this case report would help understand the importance of genotype-phenotype discrepancy.

Y Haplogroup Distribution in Korean and Other Populations / 대한법의학회지

With globalization, international exchange has increased. Accordingly, the necessity for individual identification using genetic polymorphism has also increased. Paternal lineages are distributed differently, and different distribution patterns can be used to predict ancestry. We studied the distribution pattern of different paternal lineages in Korea and compared them with other populations. All 30 SNPs on the Y chromosome were selected for paternal lineage confirmation. Loci that could subclassify haplogroup O, the most frequent in the East Asian population, were added. After multiplex amplification for the target loci, SBE reactions were set up for each SNP site. One hundred Korean men as well as 60 Chinese, 60 Japanese, 19 African-American, 48 Caucasian, and 47 Mexican American were tested and compared. Five Y haplogroups [C (C3), D (D2), NO, O, Q (Q1a1)] were found in Koreans, with haplogroup O being the most frequent. Haplogroup O sub-classified into O* (24%), O1 (6%), O2b (39%), O3a3c (4%), O3a3c1 (13%), and O3a3b(1%). This distribution pattern was similar to that of Chinese or Japanese, but minor differences were noted. With Fst, the Korean and Japanese patterns were close (0.01757) when using 6 SNPs. There were significant differences between Koreans and African Americans, Caucasians and Mexican Americans, and they were easily discernible without requiring haplogroup O sub-classification. Sub-classification of haplogroup O is likely to be useful for East Asia group comparisons. Additional studies in populations from different areas of China or Japan or studies of mtDNA or autosomes may enhance the discrimatory power of genetic polymorphism in different Asian populations.

Effect of Neurotrophins and Depolarization on Survival of Spiral Ganglion Neurons in Dissociation Cell Culture / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Several neurotrophic factors have been shown to play an essential trophic role in the development, maintenance and regulation of neuronal function. Specific neurotrophins are currently used in clinical trials for the treatment of some neurodegenerative diseases. The purposes of this experiment were twofold. Firstly, we aimed to determine the trophic effects of BDNF, NT-3, and 25 mM K+ on auditory neurons in dissociated cultures of early postnatal spiral ganglia. Secondly, we tried to collect pure neural cells after dissociating the spiral ganglions using the immunomagnetic sorting method with one of neuronal surface antigens. MATERIALS AND METHODS: Dissociated spiral ganglion cell cultures were pre-pared from cochleae of Sprague Dawley rats of 5-6 days old, and maintained in a neurobasal medium with modified N2 supplements. BDNF (50 ng/ml), NT-3 (50 ng/ml), and 25 mM K+ were added to the cultures, respectively. These cells were grown during the time course (24hr, 48hr, 72hr, 98hr) and stained with NF-200 to identify survival of spiral ganglion neurons. Immunomagnetic cell sorting for separation of spiral ganglion neurons in dissociated cells was carried out using the MiniMACS Separating System. Magnetically separated cells were analysed by flow cytometry. RESULTS: Survival of the auditory neurons in the dissociated cells was significantly increased by addition of BDNF, NT-3, and 25K. The effect of 25 mM K+ on neuronal survival showed the highest in the experimental conditions. BDNF dramatically increased the neurite length compared with those under other conditions. After immunomagnetic sorting in dissociated cultures, spiral ganglion neurons were shown to contain 50% of the fluorescently labeled positive cells. CONCLUSIONS: Neurotrophins (BDNF, NT-3) and depolarization by 25 mM K+ were essential trophic factors for postnatal auditory neurons and BDNF stimulated neuritogenesis in cultured spiral ganglion neurons. The immunomagnetic cell sorting method is not appropriate for collecting pure neural cells from the dissociated cells of spiral ganglia (50% purity).