Short-tandem repeat analysis in seven Chinese regional populations

Genetic Structure and Forensic Utility of 23 Autosomal STRs of the Ethnic Lao Groups From Laos and Thailand

The Lao Isan and Laotian are the major groups in the area of present-day northeastern Thailand and Laos, respectively. Several previous genetic and forensic studies indicated an admixed genetic structure of Lao Isan with the local Austroasiatic speaking groups, e.g. Khmer, whereas there is a paucity of reporting Laotian’s forensic short tandem repeats (STRs). Here, we newly generated 451 genotypes of seven Lao Isan and three Laotian populations (two Lao Lum and one Lao Thoeng) using 23 autosomal STRs embedded in Verifiler^TM plus PCR Amplification kit. We reported allelic frequency and forensic parameters in different dataset: combined ethnic Lao groups, combined Lao Isan populations and combined Laotians. Overall, the forensic parameter results indicate that this set of STRs is suitable for forensic investigation. The anthropological results revealed the genetic homogeneity of Tai-Kadai speaking Lao groups from Thailand and Laos, consistent with previous studies, while the Austroasiatic speaking groups from southern Laos showed genetic relatedness to both Lao Isan and Khmer. In sum, STRs allelic frequency results can provide the genetic backgrounds of populations which is useful for anthropological research and also strengthens the regional forensic database in both countries.

Microsatellite Instability Analysis (MSA) for Bladder Cancer: Past History and Future Directions

Microsatellite instability (MSI), the spontaneous loss or gain of nucleotides from repetitive DNA tracts, is a diagnostic phenotype for gastrointestinal, endometrial, colorectal, and bladder cancers; yet a landscape of instability events across a wider variety of cancer types is beginning to be discovered. The epigenetic inactivation of the MLH1 gene is often associated with sporadic MSI cancers. Recent next-generation sequencing (NGS)-based analyses have comprehensively characterized MSI-positive (MSI+) cancers, and several approaches to the detection of the MSI phenotype of tumors using NGS have been developed. Bladder cancer (here we refer to transitional carcinoma of the bladder) is a major cause of morbidity and mortality in the Western world. Cystoscopy, a gold standard for the detection of bladder cancer, is invasive and sometimes carries unwanted complications, while its cost is relatively high. Urine cytology is of limited value due to its low sensitivity, particularly to low-grade tumors. Therefore, over the last two decades, several new "molecular assays" for the diagnosis of urothelial cancer have been developed. Here, we provide an update on the development of a microsatellite instability assay (MSA) and the development of MSA associated with bladder cancers, focusing on findings obtained from urine analysis from bladder cancer patients as compared with individuals without bladder cancer. In our review, based on over 18 publications with approximately 900 sample cohorts, we provide the sensitivity (87% to 90%) and specificity (94% to 98%) of MSA. We also provide a comparative analysis between MSA and other assays, as well as discussing the details of four different FDA-approved assays. We conclude that MSA is a potentially powerful test for bladder cancer detection and may improve the quality of life of bladder cancer patients.

Autosomal Microsatellite Investigation Reveals Multiple Genetic Components of the Highlanders from Thailand

The hill tribes of northern Thailand comprise nine officially recognized groups: the Austroasiatic-speaking (AA) Khmu, Htin and Lawa; the Hmong-Mien-speaking (HM) IuMien and Hmong; and the Sino-Tibetan-speaking (ST) Akha, Karen, Lahu and Lisu. Except the Lawa, the rest of the hill tribes migrated into their present habitats only very recently. The Thai hill tribes were of much interest to research groups focusing on study of cultural and genetic variation because of their unique languages and cultures. So far, there have been several genetic studies of the Thai hill tribes. However, complete forensic microsatellite database of the Thai hill tribes is still lacking. To construct such database, we newly generated 654 genotypes of 15 microsatellites commonly used in forensic investigation that belong to all the nine hill tribes and also non-hill tribe highlanders from northern Thailand. We also combined 329 genotypes from previous studies of northern Thai populations bringing to a total of 983 genotypes, which were then subjected to genetic structure and population relationships analyses. Our overall results indicated homogenous genetic structure within the HM- and Tai-Kadai (TK)-speaking groups, large genetic divergence of the HM-speaking Hmong but not IuMien from the other Thai groups, and genetic heterogeneity within the ST- and AA-speaking groups, reflecting different population interactions and admixtures. In addition to establishing genetic relationships within and among these populations, our finding, which provides a more complete picture of the forensic microsatellite database of the multiple Thai highland dwellers, would not only serve to expand and strengthen forensic investigation in Thailand, but would also benefit its neighboring countries of Laos and Myanmar, from which many of the Thai hill tribes originated and where large populations of these ethnic groups still reside.

Search for More Effective Microsatellite Markers for Forensics With Next-Generation Sequencing

Published by the Combined DNA Index System (CODIS) program of the Federal Bureau of Investigation (FBI) in 1997, the 13 core short tandem repeat (STR) loci are widely adopted as genetic markers in forensic applications, e.g., identity testing and paternity testing. However, these loci may be biased and suffer from reduced sensitivities toward specific population groups. In addition, the rapid growth of entries in forensic databases raises the chance of random hits, which can cause false recognitions of criminal suspects. A solution to these problems is to introduce more effective STR markers. The availability of whole genome sequencing enables us to identify more reliable STRmarkers for forensic applicationscomputationally. In this paper, we proposed an algorithm to identify STR markers with high discriminative abilities from the next-generation sequencing data. Our algorithm could select a customized set of loci for a given population with pre-specified discriminative thresholds. We have applied the method to 320 Chinese individuals from the 1000 Genomes Project and obtained various numbers of loci, which were able to statistically identify an individualworldwide and had higher combined powers of discrimination and combined probabilities of exclusion than the existing CODIS 13 loci. For identity testing, themean frequencyofDNAprofile (FDP) with the selected 11 STRs was smaller than that with CODIS 13 STRs by student's t-test. With more loci, much smaller FDPs were obtained. The databasematching probabilities for selected loci were also lower than that for CODIS 13 STRs in a database with 10 billion entries. Moreover, the selected loci were able to provide considerably low chance of random profile matches so that statistically no false positives could occur. The selected loci also reduced the risk of random allele matches when doing the familial search, with lower random allele matching probabilities. In addition, the selected STRs were statistically better than CODIS STRs for paternity testing in our simulated data, with lower probabilities of false inclusions and exclusions.