scholarly journals Comparative analysis of allele variation using allele frequencies according to sample size in Korean population

2021 ◽  
Vol 43 (11) ◽  
pp. 1301-1305
Author(s):  
Hyun-Chul Park ◽  
Eu-Ree Ahn ◽  
Sang-Cheul Shin
Keyword(s):  
Comparative Analysis ◽  
Sample Size ◽  
Allele Frequency ◽  
Tandem Repeats ◽  
Population Studies ◽  
Forensic Genetics ◽  
Sampling Bias ◽  
Allele Frequencies ◽  
Rare Alleles ◽  
Allele Variation

Abstract Background Allele frequency using short tandem repeats (STRs) is used to calculate likelihood ratio for database match, to interpret DNA mixture and to estimate ethnic groups in forensic genetics. In Korea, three population studies for 23 STR loci have been conducted with different sample size for forensic purposes. Objective We performed comparative analysis to determine how the difference of sample size affects the allele frequency and allele variation within same ethnic population (i.e. Korean). Furthermore, this study was conducted to check how the sampling group and multiplex kit also affect allele variation such as rare alleles and population specific alleles. Methods To compare allele variation, we used allele frequencies of three population data published from three Korean forensic research groups. Allele frequencies were calculated using different sample sizes and multiplex kits: 526, 1000, and 2000 individuals, respectively. Results The results showed the different distribution of allele frequencies in some loci. There was also a difference in the number of rare alleles observed by the sample size and sampling bias. In particular, an allele of 9.1 in the D2S441 locus was not observed in population study with 526 individuals due to multiplex kits. Conclusion Because the allele frequencies play an important role in forensic genetics, even if the samples are derived from the same population, it is important to consider the effects of sample size, sampling bias, and selection of multiplex kits in population studies.

scholarly journals The STRidER Report on Two Years of Quality Control of Autosomal STR Population Datasets

Genes ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 901
Author(s):  
Martin Bodner ◽  
Walther Parson
Keyword(s):  
Quality Control ◽  
Allele Frequency ◽  
Error Rate ◽  
Tandem Repeats ◽  
Forensic Genetics ◽  
Quality Standard ◽  
Reference Database ◽  
Autosomal Str ◽  
Scientific Papers ◽  
High Quality Standard

STRidER, the STRs for Identity ENFSI Reference Database, is a curated, freely publicly available online allele frequency database, quality control (QC) and software platform for autosomal Short Tandem Repeats (STRs) developed under the endorsement of the International Society for Forensic Genetics. Continuous updates comprise additional STR loci and populations in the frequency database and many further STR-related aspects. One significant innovation is the autosomal STR data QC provided prior to publication of datasets. Such scrutiny was lacking previously, leaving QC to authors, reviewers and editors, which led to an unacceptably high error rate in scientific papers. The results from scrutinizing 184 STR datasets containing >177,000 individual genotypes submitted in the first two years of STRidER QC since 2017 revealed that about two-thirds of the STR datasets were either being withdrawn by the authors after initial feedback or rejected based on a conservative error rate. Almost no error-free submissions were received, which clearly shows that centralized QC and data curation are essential to maintain the high-quality standard required in forensic genetics. While many errors had minor impact on the resulting allele frequencies, multiple error categories were commonly found within single datasets. Several datasets contained serious flaws. We discuss the factors that caused the errors to draw the attention to redundant pitfalls and thus contribute to better quality of autosomal STR datasets and allele frequency reports.

scholarly journals STATISTICAL STUDIES ON PROTEIN POLYMORPHISM IN NATURAL POPULATIONS. III. DISTRIBUTION OF ALLELE FREQUENCIES AND THE NUMBER OF ALLELES PER LOCUS

Genetics ◽  
1980 ◽  
Vol 94 (4) ◽  
pp. 1039-1063
Author(s):  
Ranajit Chakraborty ◽  
Paul A Fuerst ◽  
Masatoshi Nei
Keyword(s):  
Molecular Weight ◽  
Allele Frequency ◽  
Frequency Distribution ◽  
Gene Frequency ◽  
Natural Populations ◽  
Allele Frequencies ◽  
Protein Polymorphism ◽  
Allele Frequency Distribution ◽  
Wide Range ◽  
Rare Alleles

ABSTRACT With the aim of understanding the mechanism of maintenance of protein polymorphism, we have studied the properties of allele frequency distribution and the number of alleles per locus, using gene-frequency data from a wide range of organisms (mammals, birds, reptiles, amphibians, Drosophila and non-Drosophila invertebrates) in which 20 or more loci with at least 100 genes were sampled. The observed distribution of allele frequencies was U-shaped in all of the 138 populations (mostly species or subspecies) examined and generally agreed with the theoretical distribution expected under the mutation-drift hypothesis, though there was a significant excess of rare alleles (gene frequency, 0 ~ 0.05) in about a quarter of the populations. The agreement between the mutation-drift theory and observed data was quite satisfactory for the numbers of polymorphic (gene frequency, 0.05 ~ 0.95) and monomorphic (0.95 ~ 1.O) alleles.—The observed pattern of allele-frequency distribution was incompatible with the prediction from the overdominance hypothesis. The observed correlations of the numbers of rare alleles, polymorphic alleles and monomorphic alleles with heterozygosity were of the order of magnitude that was expected under the mutation-drift hypothesis. Our results did not support the view that intracistronic recombination is an important source of genetic variation. The total number of alleles per locus was positively correlated with molecular weight in most of the species examined, and the magnitude of the correlation was consistent with the theoretical prediction from mutation-drift hypothesis. The correlation between molecular weight and the number of alleles was generally higher than the correlation between molecular weight and heterozygosity, as expected.

scholarly journals Analysis of allele frequencies of the selected 15 autosomal STR markers in Tikrit population – Iraq with comparison to Middle Eastern, African, and Europeans

2021 ◽  
pp. 75-84
Author(s):  
Maan Hasan Salih ◽  
Akeel Hussain Ali Al-Assie ◽  
Majeed Arsheed Sabbah
Keyword(s):  
Tandem Repeats ◽  
Human Genetics ◽  
Forensic Genetics ◽  
Middle Eastern ◽  
Allele Frequencies ◽  
Match Probability ◽  
Discrimination Power ◽  
Str Loci ◽  
Dna Database ◽  
Autosomal Str

Short tandem repeats (STRs) have been recommended as the highest polymorphic loci among the humana DNA regions. Therefore, STRs are agreeable to many genetic fields like forensic, population genetics and anthropological studies. The main aim of this research is to evaluate the autosomal STRs in Tikrit city-Iraq, to expand the human genetics database and forensic genetics analysis. The DNA database was obtained from 306 unrelated volunteers from native Tikrit population-Iraq, using 15 autosomal STR loci. The current study determined the allele frequencies in the Tikrit population and then compared them with other national Iraqi populations as well as with populations in the Middle East, Africa, and Europe. The highest level of heterozygosity was observed in D8S1179 and TH01 loci (0.797), while the less level was shown by CSF1PO (0.48). The departure from HWE Equilibrium was recorded in only 3 STR loci from a total of 15 loci analyzed (p<0.003). The Combined Match Probability (CMP) for 15 autosomal STR was 1 in 7.89208×10-19 and the Combined Discrimination Power (CDP) was 0.9999999997. The discrimination power (DP) was especially high in D2S1338, D18S51, D19S433 and D21S11. Based on the results observed in a Dendrogram, Tikrit population was clustered with other populations, likely reflecting the historical and geographical factors. D2S1338, D18S51, D19S433 and D21S11 markers were recognized as suitable for forensic genetics analysis in Tikrit population. Also, the 15 STRs markers provide information for the studies of genetic distances between the current study and other included populations to be compared with this study.

scholarly journals Estimation of Cry3Bb1 resistance allele frequency in field populations of western corn rootworm using a genetic marker

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Alan Willse ◽  
Lex Flagel ◽  
Graham Head
Keyword(s):  
Allele Frequency ◽  
Western Corn Rootworm ◽  
Allele Frequencies ◽  
Chromosome 8 ◽  
Corn Belt ◽  
Corn Rootworm ◽  
Resistance Allele ◽  
Response To Selection ◽  
The Us ◽  
Causal Allele

Abstract Following the discovery of western corn rootworm (WCR; Diabrotica virgifera virgifera) populations resistant to the Bacillus thuringiensis (Bt) protein Cry3Bb1, resistance was genetically mapped to a single locus on WCR chromosome 8 and linked SNP markers were shown to correlate with the frequency of resistance among field-collected populations from the US Corn Belt. The purpose of this paper is to further investigate the relationship between one of these resistance-linked markers and the causal resistance locus. Using data from laboratory bioassays and field experiments, we show that one allele of the resistance-linked marker increased in frequency in response to selection, but was not perfectly linked to the causal resistance allele. By coupling the response to selection data with a genetic model of the linkage between the marker and the causal allele, we developed a model that allowed marker allele frequencies to be mapped to causal allele frequencies. We then used this model to estimate the resistance allele frequency distribution in the US Corn Belt based on collections from 40 populations. These estimates suggest that chromosome 8 Cry3Bb1 resistance allele frequency was generally low (&lt;10%) for 65% of the landscape, though an estimated 13% of landscape has relatively high (&gt;25%) resistance allele frequency.

Bayesian approach to discriminant problems for count data with application to multilocus short tandem repeat dataset

2020 ◽  
Vol 19 (2) ◽  
Author(s):  
Koji Tsukuda ◽  
Shuhei Mano ◽  
Toshimichi Yamamoto
Keyword(s):  
Sample Size ◽  
Classification Accuracy ◽  
Tandem Repeats ◽  
Bayes Factor ◽  
Characteristic Curve ◽  
Geometric Mean ◽  
Previous Method ◽  
Threshold Adjustment ◽  
Two Populations ◽  
Short Tandem

AbstractShort Tandem Repeats (STRs) are a type of DNA polymorphism. This study considers discriminant analysis to determine the population of test individuals using an STR database containing the lengths of STRs observed at more than one locus. The discriminant method based on the Bayes factor is discussed and an improved method is proposed. The main issues are to develop a method that is relatively robust to sample size imbalance, identify a procedure to select loci, and treat the parameter in the prior distribution. A previous study achieved a classification accuracy of 0.748 for the g-mean (geometric mean of classification accuracies for two populations) and 0.867 for the AUC (area under the receiver operating characteristic curve). We improve the maximum values for the g-mean to 0.830 and the AUC to 0.935. Computer simulations indicate that the previous method is susceptible to sample size imbalance, whereas the proposed method is more robust while achieving almost identical classification accuracy. Furthermore, the results confirm that threshold adjustment is an effective countermeasure to sample size imbalance.

scholarly journals A simple method to estimate the in-house limit of detection for genetic mutations with low allele frequencies in whole-exome sequencing analysis by next-generation sequencing

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Takumi Miura ◽  
Satoshi Yasuda ◽  
Yoji Sato
Keyword(s):  
Next Generation Sequencing ◽  
Allele Frequency ◽  
Somatic Mutations ◽  
Limit Of Detection ◽  
Allele Frequencies ◽  
Genetic Mutations ◽  
Sequencing Data ◽  
Simple Method ◽  
Whole Exome ◽  
Generation Sequencing

Abstract Background Next-generation sequencing (NGS) has profoundly changed the approach to genetic/genomic research. Particularly, the clinical utility of NGS in detecting mutations associated with disease risk has contributed to the development of effective therapeutic strategies. Recently, comprehensive analysis of somatic genetic mutations by NGS has also been used as a new approach for controlling the quality of cell substrates for manufacturing biopharmaceuticals. However, the quality evaluation of cell substrates by NGS largely depends on the limit of detection (LOD) for rare somatic mutations. The purpose of this study was to develop a simple method for evaluating the ability of whole-exome sequencing (WES) by NGS to detect mutations with low allele frequency. To estimate the LOD of WES for low-frequency somatic mutations, we repeatedly and independently performed WES of a reference genomic DNA using the same NGS platform and assay design. LOD was defined as the allele frequency with a relative standard deviation (RSD) value of 30% and was estimated by a moving average curve of the relation between RSD and allele frequency. Results Allele frequencies of 20 mutations in the reference material that had been pre-validated by droplet digital PCR (ddPCR) were obtained from 5, 15, 30, or 40 G base pair (Gbp) sequencing data per run. There was a significant association between the allele frequencies measured by WES and those pre-validated by ddPCR, whose p-value decreased as the sequencing data size increased. By this method, the LOD of allele frequency in WES with the sequencing data of 15 Gbp or more was estimated to be between 5 and 10%. Conclusions For properly interpreting the WES data of somatic genetic mutations, it is necessary to have a cutoff threshold of low allele frequencies. The in-house LOD estimated by the simple method shown in this study provides a rationale for setting the cutoff.

scholarly journals Identification and functional characterization of the extremely long allele of the serotonin transporter-linked polymorphic region

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tempei Ikegame ◽  
Yosuke Hidaka ◽  
Yutaka Nakachi ◽  
Yui Murata ◽  
Risa Watanabe ◽  
...  
Keyword(s):  
Bipolar Disorder ◽  
Psychiatric Disorders ◽  
Serotonin Transporter ◽  
Tandem Repeats ◽  
Large Population ◽  
Functional Characterization ◽  
Luciferase Assay ◽  
Elderly Subjects ◽  
Polymorphic Region ◽  
Rare Alleles

AbstractSLC6A4, which encodes the serotonin transporter, has a functional polymorphism called the serotonin transporter-linked polymorphic region (5-HTTLPR). The 5-HTTLPR consists of short (S) and long (L) alleles, each of which has 14 or 16 tandem repeats. In addition, the extralong (XL) and other rare alleles have been reported in 5-HTTLPR. Although they are more frequent in Asian and African than in other populations, the extent of variations and allele frequencies (AFs) were not addressed in a large population. Here, we report the AFs of the rare alleles in a large number of Japanese subjects (N = 2894) consisting of two cohorts. The first cohort (case-control study set, CCSS) consisted of 1366 subjects, including 485 controls and 881 patients with psychosis (bipolar disorder or schizophrenia). The second cohort (the Arao cohort study set, ACSS) consisted of 1528 elderly subjects. During genotyping, we identified 11 novel 5-HTTLPR alleles, including 3 XL alleles. One novel allele had the longest subunit ever reported, consisting of 28 tandem repeats. We named this XL28-A. An in vitro luciferase assay revealed that XL28-A has no transcriptional activity. XL28-A was found in two unrelated patients with bipolar disorder in the CCSS and one healthy subject in the ACSS who did not show depressive symptoms or a decline in cognitive function. Therefore, it is unlikely that XL28-A is associated with psychiatric disorders, despite its apparent functional deficit. Our results suggest that unraveling the complex genetic variations of 5-HTTLPR will be important for further understanding its role in psychiatric disorders.

scholarly journals The Dynamics of Gynodioecy in Plantago lanceolatu L. II. Mode of Action and Frequencies of Restorer Alleles

Genetics ◽  
1997 ◽  
Vol 147 (3) ◽  
pp. 1317-1328
Author(s):  
Anita A de Haan ◽  
Hans P Koelewijn ◽  
Maria P J Hundscheid ◽  
Jos M M Van Damme
Keyword(s):  
Cytoplasmic Male Sterility ◽  
Male Sterility ◽  
Allele Frequency ◽  
Mode Of Action ◽  
Male Fertility ◽  
Fertility Restoration ◽  
Plantago Lanceolata ◽  
Allele Frequencies ◽  
Male Sterile ◽  
Male Fertility Restoration

Male fertility in Plantago lanceolata is controlled by the interaction of cytoplasmic and nuclear genes. Different cytoplasmic male sterility (CMS) types can be either male sterile or hermaphrodite, depending on the presence of nuclear restorer alleles. In three CMS types of P. lanceolata (CMSI, CMSIIa, and CMSIIb) the number of loci involved in male fertility restoration was determined. In each CMS type, male fertility was restored by multiple genes with either dominant or recessive action and capable either of restoring male fertility independently or in interaction with each other (epistasis). Restorer allele frequencies for CMSI, CMSIIa and CMSIIb were determined by crossing hermaphrodites with “standard” male steriles. Segregation of male steriles vs. non-male steriles was used to estimate overall restorer allele frequency. The frequency of restorer alleles was different for the CMS types: restorer alleles for CMSI were less frequent than for CMSIIa and CMSIIb. On the basis of the frequencies of male steriles and the CMS types an “expected” restorer allele frequency could be calculated. The correlation between estimated and expected restorer allele frequency was significant.

scholarly journals Comparison of the Allelic Alterations between InDel and STR Markers in Tumoral Tissues Used for Forensic Purposes

Medicina ◽  
2021 ◽  
Vol 57 (3) ◽  
pp. 226
Author(s):  
Pamela Tozzo ◽  
Arianna Delicati ◽  
Anna Chiara Frigo ◽  
Luciana Caenazzo
Keyword(s):  
Colorectal Cancer ◽  
Genomic Instability ◽  
Tandem Repeats ◽  
Forensic Genetics ◽  
Tumor Type ◽  
Forensic Dna ◽  
Dna Identification ◽  
Human Dna ◽  
Tumor Transformation ◽  
Paternity Tests

Background and objectives: Over the last two decades, human DNA identification and kinship tests have been conducted mainly through the analysis of short tandem repeats (STRs). However, other types of markers, such as insertion/deletion polymorphisms (InDels), may be required when DNA is highly degraded. In forensic genetics, tumor samples may sometimes be used in some cases of human DNA identification and in paternity tests. Nevertheless, tumor genomic instability related to forensic DNA markers should be considered in forensic analyses since it can compromise genotype attribution. Therefore, it is useful to know what impact tumor transformation may have on the forensic interpretation of the results obtained from the analysis of these polymorphisms. Materials and Methods: The aim of this study was to investigate the genomic instability of InDels and STRs through the analysis of 55 markers in healthy tissue and tumor samples (hepatic, gastric, breast, and colorectal cancer) in 66 patients. The evaluation of genomic instability was performed comparing InDel and STR genotypes of tumor samples with those of their healthy counterparts. Results: With regard to STRs, colorectal cancer was found to be the tumor type affected by the highest number of mutations, whereas in the case of InDels the amount of genetic mutations turned out to be independent of the tumor type. However, the phenomena of genomic instability, such as loss of heterozygosity (LOH) and microsatellite instability (MSI), seem to affect InDels more than STRs hampering genotype attribution. Conclusion: We suggest that the use of STRs rather than InDels could be more suitable in forensic genotyping analyses given that InDels seem to be more affected than STRs by mutation events capable of compromising genotype attribution.

scholarly journals Allele frequency divergence reveals ubiquitous influence of positive selection in Drosophila

2021 ◽  
Author(s):  
Jason Bertram
Keyword(s):  
Allele Frequency ◽  
Evolutionary Biology ◽  
Polymorphic Locus ◽  
Purifying Selection ◽  
Allele Frequencies ◽  
Intermediate Allele ◽  
Genome Wide ◽  
Signature Of Selection ◽  
Basic Objective ◽  
Genomic Regions

Resolving the role of natural selection is a basic objective of evolutionary biology. It is generally difficult to detect the influence of selection because ubiquitous non-selective stochastic change in allele frequencies (genetic drift) degrades evidence of selection. As a result, selection scans typically only identify genomic regions that have undergone episodes of intense selection. Yet it seems likely such episodes are the exception; the norm is more likely to involve subtle, concurrent selective changes at a large number of loci. We develop a new theoretical approach that uncovers a previously undocumented genome-wide signature of selection in the collective divergence of allele frequencies over time. Applying our approach to temporally-resolved allele frequency measurements from laboratory and wild Drosophila populations, we quantify the selective contribution to allele frequency divergence and find that selection has substantial effects on much of the genome. We further quantify the magnitude of the total selection coefficient (a measure of the combined effects of direct and linked selection) at a typical polymorphic locus, and find this to be large (of order 1%) even though most mutations are not directly under selection. We find that selective allele frequency divergence is substantial at intermediate allele frequencies, which we argue is most parsimoniously explained by positive --- not purifying --- selection. Thus, in these populations most mutations are far from evolving neutrally in the short term (tens of generations), including mutations with neutral fitness effects, and the result cannot be explained simply as a purging of deleterious mutations.

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