Forensic Microbiological Analysis for Vaginal Fluid Identification Using Multiplex Real-Time PCR System / 대한법의학회지

Numerous methods for human body fluid identification using microbiological markers specific to different human body parts are well-established in forensic science. However, method for vaginal fluid screening have not been standardized yet. Therefore, in this study, a real-time polymerase chain reaction based assay for vaginal fluid identification was devised using bacteria residing in human vagina. This method employed three markers, namely Lactobacillus iners, Lactobacillus crispatus, and Bacteroides fragilis. L. iners and L. crispatus were chosen due to their high abundance in the vagina, whereas B. fragilis resides in the rectum. To examine the suitability of the new method for forensic microbial applications, a study of the distribution of vaginal flora in 143 Korean women was performed, along with characterization of the specificity, and performance of the new assay. Additionally, a casework study based on 130, 21, 20 and 17 DNA samples collected from the vagina, anus, saliva, blood, respectively, was carried out. L. iners (80.4%) and L. crispatus (55.2%) were detected with high abundance in the vagina of Korean women. The specificity of these markers was verified using microbial DNA from 23 species. This method could detect at least 1,000 copies/µL of microorganisms for all markers, thereby highlighting its robust sensitivity for vaginal fluid identification. The casework study confirmed these findings, with 89.2% (116/130) detection of vaginal fluid-derived DNA samples, and no false positives identified from the other sources studied. In conclusion, the developed method is expected to be efficient for preliminary microbiological analysis of vaginal samples in forensics.

Mutational analysis of whole mitochondrial DNA in patients with MELAS and MERRF diseases

Mitochondrial diseases are clinically and genetically heterogeneous disorders, which make the exact diagnosis and classification difficult. The purpose of this study was to identify pathogenic mtDNA mutations in 61 Korean unrelated families (or isolated patients) with MELAS or MERRF. In particular, the mtDNA sequences were completely determined for 49 patients. From the mutational analysis of mtDNA obtained from blood, 5 confirmed pathogenic mutations were identified in 17 families, and 4 unreported pathogenically suspected mutations were identified in 4 families. The m.3243A>G in the tRNA(Leu(UUR)) was predominantly observed in 10 MELAS families, and followed by m.8344A>G in the tRNA(Lys) of 4 MERRF families. Most pathogenic mutations showed heteroplasmy, and the rates were considerably different within the familial members. Patients with a higher rate of mutations showed a tendency of having more severe clinical phenotypes, but not in all cases. This study will be helpful for the molecular diagnosis of mitochondrial diseases, as well as establishment of mtDNA database in Koreans.

Null and Duplicated Alleles of 17 Y-STR Haplotypes in Koreans and Considerations for Forensic Application / 대한법의학회지

The analysis of Y chromosome polymorphisms has become common place for the identification of male component in forensic cases. In male/female mixtures of many rape cases, Y-STRs are also very useful for the determination of contributors' number. During the analyses of 17 Y-STR haplotypes for forensic applications using the AmpFlSTR(R) Yfiler(TM) system, a number of null and duplicated alleles (40 out of 2144 subjects) were discovered. Interestingly, two haplotypes should focus the attention on forensic interpretation of Y-STR haplotype profiles, because multiple mutational events at various loci can be interpreted as a wrong mixed or allele drop-out profile.

Change of Surname?: An application of Y-STR Haplotyping / 대한법의학회지

Y-STR haplotyping is a powerful forensic and anthropological tool for identifying male lineages. We used high-resolution Y-STR haplotyping to evaluate the possibility of an ancestral relationship between two individuals with the different surname. Of the 17 Y-STRs genotyped, 16 had identical alleles in two individuals, except for an unambiguously sporadic mutation (one-step mutation) at DYS385 locus. The common allele 11.1 (U3Ains) at DYS439 locus was also observed in these two individuals. Sequencing analysis of these alleles of two samples demonstrated an A insertion at base 3 upstream from the repeat region's first GATA motif. These findings suggested that two individuals were paternally related, even if male individuals live with different surname.