Population and forensic genetic analyses of mitochondrial DNA control region variation from six major provinces in the Korean population

Biogeographic origin and genetic characteristics of the peopling of Jeju Island based on lineage markers

BACKGROUND

Jeju Island is the largest island of South Korea, located southwest far from the mainland of Korea, and has a unique history and its own cultures that are distinguished from those of the other regions of the Korean mainland. However, the Jeju population has not been deeply investigated to date to understand their genetic structure, which may reflect their historical and geographical background.

OBJECTIVE

To identify the genetic characteristics and biogeographic origin of people of Jeju Island based on the statistical analysis of genetic data using lineage markers.

METHODS

17 Y-STRs data for 615 unrelated males and mitochondrial DNA haplogroup data for 799 unrelated individuals residing on Jeju Island were generated, and analyzed to investigate genetic diversity and genetic characteristics using statistical methods including pairwise Fst or Rst, Analysis of molecular variance (AMOVA) and Multidimensional scaling (MDS).

RESULTS

For male individuals of Jeju Island, unique genetic characteristics were observed in the analysis of Y-STRs, including low haplotype diversity, strong association with surnames, genetic difference from other regions of Korea, and common genetic variation of the Y-STR loci known to be predominant in Northern populations, such as Mongolians. Statistical analysis of the mitochondrial DNA haplogroups also revealed similar results that showed low haplogroup diversity and high frequency of haplogroup Y prevalent mostly in ethnic populations around the Sea of Okhotsk in Northeastern Asia. All these results suggest that Jeju Island is genetically distinct from other regions of Korea, possibly being a subpopulation in Korea, and related closely to Northern Asian populations.

CONCLUSION

The findings in the genetic approach could support understanding of the historical background of Jeju Island that is consistent with evidence from other multidisciplinary studies.

The Ancestry of Eastern Paraguay: A Typical South American Profile with a Unique Pattern of Admixture

Immigrants from diverse origins have arrived in Paraguay and produced important demographic changes in a territory initially inhabited by indigenous Guarani. Few studies have been performed to estimate the proportion of Native ancestry that is still preserved in Paraguay and the role of females and males in admixture processes. Therefore, 548 individuals from eastern Paraguay were genotyped for three marker sets: mtDNA, Y-SNPs and autosomal AIM-InDels. A genetic homogeneity was found between departments for each set of markers, supported by the demographic data collected, which showed that only 43% of the individuals have the same birthplace as their parents. The results show a sex-biased intermarriage, with higher maternal than paternal Native American ancestry. Within the native mtDNA lineages in Paraguay (87.2% of the total), most haplogroups have a broad distribution across the subcontinent, and only few are concentrated around the Paraná River basin. The frequency distribution of the European paternal lineages in Paraguay (92.2% of the total) showed a major contribution from the Iberian region. In addition to the remaining legacy of the colonial period, the joint analysis of the different types of markers included in this study revealed the impact of post-war migrations on the current genetic background of Paraguay.

Allele and haplotype frequencies of human leukocyte antigen-A, -B, -C, -DRB1, -DRB3/4/5, -DQA1, -DQB1, -DPA1, and -DPB1 by next generation sequencing-based typing in Koreans in South Korea

Allele frequencies and haplotype frequencies of HLA-A, -B, -C, -DRB1, -DRB3/4/5, -DQA1, -DQB1, -DPA1, and -DPB1 have been rarely reported in South Koreans using unambiguous, phase-resolved next generation DNA sequencing. In this study, HLA typing of 11 loci in 173 healthy South Koreans were performed using next generation DNA sequencing with long-range PCR, TruSight^® HLA v2 kit, Illumina MiSeqDx platform system, and Assign^™ for TruSight^™ HLA software. Haplotype frequencies were calculated using the PyPop software. Direct counting methods were used to investigate the association with DRB1 for samples with only one copy of a particular secondary DRB locus. We compared these allele types with the ambiguous allele combinations of the IPD-IMGT/HLA database. We identified 20, 40, 26, 31, 19, 16, 4, and 16 alleles of HLA-A, HLA-B, HLA-C, HLA-DRB1, HLA-DQA1, HLA-DQB1, HLA-DPA1, and HLA-DPB1, respectively. The number of HLA-DRB3/4/5 alleles was 4, 5, and 3, respectively. The haplotype frequencies of most common haplotypes were as follows: A*33:03:01-B*44:03:01-C*14:03-DRB1*13:02:01-DQB1*06:04:01-DPB1*04:01:01 (2.89%), A*33:03:01-B*44:03:01-C*14:03 (4.91%), DRB1*08:03:02-DQA1*01:03:01-DQB1*06:01:01-DPA1*02:02:02-DPB1*05:01:01 (5.41%), DRB1*04:05:01-DRB4*01:03:01 (12.72%), DQA1*01:03:01-DQB1*06:01:01 (13.01%), and DPA1*02:02:02-DPB1*05:01:01 (30.83%). In samples with only one copy of a specific secondary DRB locus, we examined its association with DRB1. We, thus, resolved 10 allele ambiguities in HLA-B, -C (each exon 2+3), -DRB1, -DQB1, -DQA1, and -DPB1 (each exon 2) of the IPD-IMGT/HLA database. Korean population was geographically close to Japanese and Han Chinese populations in the genetic distances by multidimensional scaling (MDS) plots. The information obtained by HLA typing of the 11 extended loci by next generation sequencing may be useful for more exact diagnostic tests on various transplantations and the genetic population relationship studies in South Koreans.

Second GHEP-ISFG exercise for DVI: "DNA-led" victims' identification in a simulated air crash

The Spanish and Portuguese-Speaking Working Group of the International Society for Forensic Genetics (GHEP-ISFG) has organized a second collaborative exercise on a simulated case of Disaster Victim Identification (DVI), with the participation of eighteen laboratories. The exercise focused on the analysis of a simulated plane crash case of medium-size resulting in 66 victims with varying degrees of fragmentation of the bodies (with commingled remains). As an additional difficulty, this second exercise included 21 related victims belonging to 6 families among the 66 missings to be identified. A total number of 228 post-mortem samples were represented with aSTR and mtDNA profiles, with a proportion of partial aSTR profiles simulating charred remains. To perform the exercise, participants were provided with aSTR and mtDNA data of 51 reference pedigrees -some of which deficient-including 128 donors for identification purposes. The exercise consisted firstly in the comparison of the post-mortem genetic profiles in order to re-associate fragmented remains to the same individual and secondly in the identification of the re-associated remains by comparing aSTR and mtDNA profiles with reference pedigrees using pre-established thresholds to report a positive identification. Regarding the results of the post-mortem samples re-associations, only a small number of discrepancies among participants were detected, all of which were from just a few labs. However, in the identification process by kinship analysis with family references, there were more discrepancies in comparison to the correct results. The identification results of single victims yielded fewer problems than the identification of multiple related victims within the same family groups. Several reasons for the discrepant results were detected: a) the identity/non-identity hypotheses were sometimes wrongly expressed in the likelihood ratio calculations, b) some laboratories failed to use all family references to report the DNA match, c) In families with several related victims, some laboratories firstly identified some victims and then unnecessarily used their genetic information to identify the remaining victims within the family, d) some laboratories did not correctly use "prior odds" values for the Bayesian treatment of the episode for both post-mortem/post-mortem re-associations as well as the ante-mortem/post-mortem comparisons to evaluate the probability of identity. For some of the above reasons, certain laboratories failed to identify some victims. This simulated "DNA-led" identification exercise may help forensic genetic laboratories to gain experience and expertize for DVI or MPI in using genetic data and comparing their own results with the ones in this collaborative exercise.

Analysis and interpretation of mixture DNA using AS-PCR of mtDNA

Semi-nested PCR with allele-specific (AS) primers and sequencing of mitochondrial DNA (mtDNA) were performed to analyze and interpret DNA mixtures, especially when biological materials were degraded or contained a limited amount of DNA. SNP-STR markers were available to identify the minor DNA component using AS-PCR; moreover, SNPs in mtDNA could be used when the degraded or limited amounts of DNA mixtures were not successful with SNP-STR markers. Five pairs of allele-specific primers were designed based on three SNPs (G15043A, T16362C, and T16519C). The sequence of mtDNA control region of minor components was obtained using AS-PCR and sequencing. Sequences of the amplification fragments were aligned and compared with the sequences of known suspects or databases. When this assay was used with the T16362C and T16519C SNPs, we found it to be highly sensitive for detecting small amounts of DNA (∼30 pg) and analyzing DNA mixtures of two contributors, even at an approximately 1‰ ratio of minor and major components. An exception was tests based on the SNP G15043A, which required approximately 300 pg of a 1% DNA mixture. In simulated three contributor DNA mixtures (at rate of 1:1:1), control region fragments from each contributor were detected and interpreted. AS-PCR combined with semi-nested PCR was successfully used to identify the mtDNA control region of each contributor, providing biological evidence for excluding suspects in forensic cases, especially when biological materials were degraded or had a limited amount of DNA.

Bio-Anthropological Studies on Human Skeletons from the 6th Century Tomb of Ancient Silla Kingdom in South Korea

In November and December 2013, unidentified human skeletal remains buried in a mokgwakmyo (a traditional wooden coffin) were unearthed while conducting an archaeological investigation near Gyeongju, which was the capital of the Silla Kingdom (57 BCE– 660 CE) of ancient Korea. The human skeletal remains were preserved in relatively intact condition. In an attempt to obtain biological information on the skeleton, physical anthropological, mitochondrial DNA, stable isotope and craniofacial analyses were carried out. The results indicated that the individual was a female from the Silla period, of 155 ± 5 cm height, who died in her late thirties. The maternal lineage belonged to the haplogroup F1b1a, typical for East Asia, and the diet had been more C₃- (wheat, rice and potatoes) than C₄-based (maize, millet and other tropical grains). Finally, the face of the individual was reconstructed utilizing the skull (restored from osseous fragments) and three-dimensional computerized modeling system. This study, applying multi-dimensional approaches within an overall bio-anthropological analysis, was the first attempt to collect holistic biological information on human skeletal remains dating to the Silla Kingdom period of ancient Korea.

Genetic analysis of mitochondrial DNA control region variations in four tribes of Khyber Pakhtunkhwa, Pakistan

Due to its geo strategic position at the crossroad of Asia, Pakistan has gained crucial importance of playing its pivotal role in subsequent human migratory events, both prehistoric and historic. This human movement became possible through an ancient overland network of trails called "The Silk Route" linking Asia Minor, Middle East China, Central Asia and Southeast Asia. This study was conducted to analyze complete mitochondrial control region samples of 100 individuals of four major Pashtun tribes namely, Bangash, Khattak, Mahsuds and Orakzai in the province of Khyber Pakhtunkhwa, Pakistan. All Pashtun tribes revealed high genetic diversity which is comparable to the other Central Asian, Southeast Asian and European populations. The configuration of genetic variation and heterogeneity further unveiled through Multidimensional Scaling, Principal Component Analysis and phylogenetic analysis. The results revealed that Pashtun are the composite mosaic of West Eurasian ancestry of numerous geographic origin. They received substantial gene flow during different invasive movements and have a high element of the Western provenance. The most common haplogroups reported in this study are: South Asian haplogroups M (28%) and R (8%); whereas, West Asians haplogroups are present, albeit in high frequencies (67%) and widespread over all; HV (15%), U (17%), H (9%), J (8%), K (8%), W (4%), N (3%) and T (3%). Moreover, we linked the unexplored genetic connection between Ashkenazi Jews and Pashtun. The presence of specific haplotypes J1b (4%) and K1a1b1a (5%) pointed to a genetic connection of Jewish conglomeration in Khattak tribe. This was a result of an ancient genetic influx in the early Neolithic period that led to the formation of a diverse genetic substratum in present day Pashtun.