Set up of cutoff thresholds for kinship determination using SNP loci.

The usefulness of single nucleotide polymorphism (SNP) loci for kinship testing has been demonstrated in many case works, and suggested as a promising marker for relationship identification. For interpreting results based on the calculation of the likelihood ratio (LR) in kinship testing, it is important to prepare cutoffs for respective relatives which are dependent on genetic relatedness. For this, analysis using true pedigree data is significant and reliable as it reflects the actual frequencies of markers in the population. In this study, the kinship index was explored through 1209 parent-child pairs, 1373 full sibling pairs, and 247 uncle-nephew pairs using 136 SNP loci. The cutoffs for LR were set up using different numbers of SNP loci with accuracy, sensitivity, and specificity. It is expected that this study can support the application of SNP loci-based kinship testing for various relationships.

Kinship Testing Based on SNPs Using Microarray System.

BACKGROUND: Kinship testing using biallelic SNP markers has been demonstrated to be a promising approach as a supplement to standard STR typing, and several systems, such as pyrosequencing and microarray, have been introduced and utilized in real forensic cases. The Affymetrix microarray containing 169 autosomal SNPs developed for forensic application was applied to our practical case for kinship analysis that had remained inconclusive due to partial STR profiles of degraded DNA and possibility of inbreeding within the population. CASE REPORT: 169 autosomal SNPs were typed on array with severely degraded DNA of two bone samples, and the kinship compared to genotypes in a reference database of their putative family members. RESULTS: Two bone samples remained unidentified through traditional STR typing with partial profiles of 10 or 14 of 16 alleles. Because these samples originated from a geographically isolated population, a cautious approach was required when analyzing and declaring true paternity only based on PI values. In a supplementary SNP typing, 106 and 78 SNPs were obtained, and the match candidates were found in each case with improved PI values than using only STRs and with no discrepant SNPs in comparison. CONCLUSION: Our case showed that the utility of multiple SNPs on array is expected in practical forensic caseworks with an establishment of reference database.

Forensic application of SNP-based resequencing array for individual identification.

In forensic field investigations using single nucleotide polymorphism (SNP) have been performed for various purposes. Based on the characteristics of SNP, it is essential to have a multi-amplification technology and a platform to analyze the amplified SNP markers accurately. Here, we have developed a platform based on the resequencing array of Affymetrix analyzing 169 SNP markers amplified via multiplex PCR and verified its forensic application. From the 1000 genomes database, the SNP markers were selected under the condition of less than 0.04 fixation index (Fst) and 0.3 linkage disequilibrium (LD) R(2) value, and 0.4-0.5 minor allele frequency (MAF). It was identified that more than 120 out of 169 SNPs were able to be typed with approximately 10pg of DNA and artificially degraded samples in various tests. The DNA extracted from bones also showed a similar rate of success. The results indicated that our platform has a potential role to assist the current short tandem repeat (STR) method in analyzing harsh samples, such as bone or degraded DNA. With a possibility to expand the platform, it was expected to apply to various uses in different areas in the future.

Identification of radiation-specific responses from gene expression profile.

The responses to ionizing radiation (IR) in tumors are dependent on cellular context. We investigated radiation-related expression patterns in Jurkat T cells with nonsense mutation in p53 using cDNA microarray. Expression of 2400 genes in gamma-irradiated cells was distinct from other stimulations like anti-CD3, phetohemagglutinin (PHA) and concanavalin A (ConA) in unsupervised clustering analysis. Among them, 384 genes were selected for their IR-specific changes to make 'RadChip'. In spite of p53 status, every type of cells showed similar patterns in expression of these genes upon gamma-radiation. Moreover, radiation-induced responses were clearly separated from the responses to other genotoxic stress like UV radiation, cisplatin and doxorubicin. We focused on two IR-related genes, phospholipase Cgamma2 (PLCG2) and cytosolic epoxide hydrolase (EPHX2), which were increased at 12 h after gamma-radiation in RT-PCR. TPCK could suppress the induction of these two genes in either of Jurkat T cells and PBMCs, which might suggest the transcriptional regulation of PLCG2 and EPHX2 by NF-kappaB upon gamma-radiation. From these results, we could identify the IR-specific genes from expression profiling, which can be used as radiation biomarkers to screen radiation exposure as well as probing the mechanism of cellular responses to ionizing radiation.