Kyoung Don Kwak

Y-chromosomal DNA haplogroups and their implications for the dual origins of the Koreans

We have analyzed eight Y-chromosomal binary markers (YAP, RPS4Y711, M9, M175, LINE1, SRY+465, 47z, and M95) and three Y-STR markers (DYS390, DYS391, and DYS393) in 738 males from 11 ethnic groups in east Asia in order to study the male lineage history of Korea. Haplogroup DE-YAP was found at a high frequency only in Japan but was also present at low frequencies in northeast Asia, including 2.5% in Korea, suggesting a northern origin for these chromosomes. Haplogroup C-RPS4Y711 was present in Korea and Manchuria at moderate frequencies: higher than in populations from southeast Asia, but lower than those in the northeast, which may imply a northern Asian expansion of these lineages, perhaps from Mongolia or Siberia. The major Y-chromosomal expansions in east Asia were those of haplogroup O-M175 (and its sublineages). This haplogroup is likely to have originated in southern east Asia and subsequently expanded to all of east Asia. The moderate frequency of one sublineage in the Koreans, haplogroup O-LINE1 (12.5%), could be a result of interaction with Chinese populations. The age of another sublineage, haplogroup O-SRY+465, and Y-STR haplotype diversity provide evidence for relatively recent male migration, originally from China, through Korea into Japan. In conclusion, the distribution pattern of Y-chromosomal haplogroups reveals the complex origin of the Koreans, resulting from genetic contributions involving the northern Asian settlement and range expansions mostly from southern-to-northern China.

Y-chromosomal STR haplotypes and their applications to forensic and population studies in east Asia

We have analyzed 11 Y-STR loci (DYS19, the two DYS385 loci, DYS388, DYS389I/II, DYS390, DYS391, DYS392, DYS393, DXYS156Y) in 700 males from ten ethnic groups in east Asia in order to evaluate their usefulness for forensic and population genetic studies. A total of 644 different haplotypes were identified, among which 603 (86.14%) were individual-specific. The haplotype diversity averaged over all populations was 0.9997; using only the nine Y-STRs comprising the “minimal haplotype” (excluding DYS388 and DXYS156Y) it was 0.9996, a value similar to that found in 1924 samples from other Asian populations (0.9996; Lessig et al. Legal Medicine 5(2003) 160–163), and slightly higher than in European populations (0.9976; n=11,610; Roewer et al. For Sci International (2001) 118:103–111). All of the individual east Asian populations examined here had high haplotype diversity (≥0.997), except for the Mongolians (0.992) and Manchurians (0.960). The most frequent haplotype identified by the nine markers was present at only 1% (7/700). Population comparisons based on ΦST or ρ genetic distance measures revealed clustering according to the traditional northeast–southeast distinction, but with exceptions. For example, the Yunnan population from southern China lay among the northern populations, possibly reflecting recent migration, while the Korean population, traditionally considered northern, lay at the boundary between northern and southern populations. An admixture estimate suggested 55(51–59)% northern, 45(41–49)% southern contribution to the Koreans, illustrating the complexity of the genetic history of this region.

Y-Chromosome multiplexes and their potential for the DNA profiling of Koreans

Abstract We have developed four multiplex genotyping systems (GeneKin Y-STR multiplexes) using silver staining with allelic ladders for ten Y-chromosome STR markers (DYS19, DYS385, DYS388, DYS389I/II, DYS390, DYS391, DYS392, DYS393 and DXYS156Y), with a view towards the application of rapid and simple genotyping assay methods for DNA profiling. The GeneKin Y-STR multiplexes developed have followed the published nomenclature and ISFG guidelines for STR analysis. Allele and haplotype frequencies at these Y-STRs loci were analysed by PCR amplification using the GeneKin Y-STR multiplexes, followed by denaturing polyacrylamide gel electrophoresis in 316 unrelated males in the Korean population. A total of 295 different haplotypes were found, 279 of them being unique. Gene diversity ranged from 0.4026 at DYS391 to 0.9606 at DYS385. The haplotype diversity value (which is the same as the discrimination index) calculated from all ten loci combined was 0.9995, which is informative. Our results revealed that a set of ten Y-STRs can discriminate between most of the male individuals in the Korean population (discrimination capacity: 93.35%). The Y-STR multiplexes thus provide useful information for forensic analysis and paternity tests and can also be of great benefit for providing information not normally available from autosomal DNA systems.

Y-chromosome STR haplotype profiling in the Korean population

Allele and haplotype frequencies of seven Y-chromosome STR loci were determined from a sample of 330 unrelated males in the Korean population.

Korean population genetic data for eleven STR loci

Allele frequency and forensic parameters for eleven STR loci were surveyed in a random sample from the Korean population.

Forensic genetic analysis of nine miniSTR loci in the Korean population

Nine miniSTR loci were analyzed in 191 unrelated individuals from Korea using three multiplex PCR systems (multiplex I: D1S1677, D2S441 and D4S2364; multiplex II: D10S1248, D14S1434 and D22S1045; multiplex III: D12S391, D16S3253 and D20S161). Due to the short PCR amplicons (< 145 bp), miniSTR systems can effectively be used in forensic analysis with highly degraded DNAs. Allele frequencies and forensic parameters were calculated to evaluate their usefulness in forensic casework. The Exact Test demonstrated that all loci surveyed here were found to be no deviation from Hardy-Weinberg equilibrium, except two miniSTR markers (D4S2364 and D16S3253). When we compared the distribution of genetic variation of six miniSTR markers (D1S1677, D2S441, D4S2364, D10S1248, D14S1434 and D22S1045), the Exact Test revealed significant differences (P < 0.05) between the Korean sample studied here and almost all of other samples of East Asian and European populations. The combined probability of match calculated from nine miniSTR loci was 1.28 x 10(-8), which is high degree of polymorphism. Thus, the miniSTR system, combined with other valuable miniSTR markers, may be suitable for recovering useful information in analyzing degraded DNA samples.

A preliminary study on the origin of Koreans based on Y-STR variation

To investigate the origin of Koreans, we examined the 12-locus Y-chromosome short tandem repeat (Y-STR) variation in a sample of 310 unrelated males from three localities (Gochang, Andong and Geoje) in Korea and statistically analyzed the previously published four Y-STR databases (n = 1655) of Korean population. The median joining network of 9-locus Y-STR haplotypes inferred as haplogroup O2b-SRY+465 showed a “star cluster” indicative of a population expansion from a centrally positioned haplotype. The central haplotype in the “star cluster” was the most frequently occurring Y-STR haplotype among the Korean male gene pool (6%, 127 of 1965, 10,14,12,13,14,16,13,13,23, for loci DYS391, DYS389I, DYS439, DYS438, DYS437, DYS19, DYS392, DYS393, and DYS390), which was shared among all seven datasets. Based on the “star cluster” pattern from both our data (41%, 128 of 310) and those previously published (34%, 563 of 1655), we suggest that the most frequent Y-STR haplotype among the Korean male gene pool seems to be the Korean modal (ancestral) haplotype. Further study with additional Y-STR and Y-SNP data of the east Asian populations as well as Korean population are needed to providing a genetic clue for the “star cluster” (O2b-SRY+465) associated with the ethnohistoric events of the Koreans.