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Aim: The aimof this study is to investigate if Preimplantation Genetic Testing (PGT) can effectively identify unreported variants according to American College of Medical Genetics and Genomics (ACMG)to prevent citrullinemia type 1 affection. Design: This study involves a detailed case analysis of a family with history of citrullinemia type 1, focusing on the use of PGT for monogenic diseases (PGT-M). The genetic variants were identified using ACMG guidelines, and PGT was employed to prevent the inheritance of these variants. The study included haplotype analysis and Sanger sequencing to confirm the results. Results: The study identified previously unreported variations in the ASS1 gene causing citrullinemia type 1. PGT successfully prevented the transmission of these variants, resulting in the birth of a healthy fetus. However, challenges such as allele dropout (ADO) and gene recombination were encountered during haplotype analysis, which could potentially defeat the diagnosis. The study demonstrated that combining haplotype analysis with Sanger sequencing can enhance the accuracy of PGT. Conclusion: Preimplantation Genetic Testing (PGT) targeting likely pathogenic and pathogenic variants in the ASS1 gene, as rated by ACMG, allows the birth of healthy infants free from citrullinemia type 1. Additionally, the establishment of single haplotypes and Sanger sequencing can reduce the misdiagnosis rate caused by allele dropout (ADO) and genetic recombination. [ABSTRACT FROM AUTHOR]

The black‐footed cat (Felis nigripes) is endemic to the arid regions of southern Africa. One of the world's smallest wild felids, the species occurs at low densities and is secretive and elusive, which makes ecological studies difficult. Genetic data could provide key information such as estimates on population size, sex ratios, and genetic diversity. In this study, we test if microsatellite loci can be successfully amplified from scat samples that could be noninvasively collected from the field. Using 21 blood and scat samples collected from the same individuals, we statistically tested whether nine microsatellites previously designed for use in domestic cats can be used to identify individual black‐footed cats. Genotypes recovered from blood and scat samples were compared to assess loss of heterozygosity, allele dropout, and false alleles resulting from DNA degradation or PCR inhibitors present in scat samples. The microsatellite markers were also used to identify individuals from scats collected in the field that were not linked to any blood samples. All nine microsatellites used in this study were amplified successfully and were polymorphic. Microsatellite loci were found to have sufficient discriminatory power to distinguish individuals and identify clones. In conclusion, these molecular markers can be used to monitor populations of wild black‐footed cats noninvasively. The genetic data will be able to contribute important information that may be used to guide future conservation initiatives. [ABSTRACT FROM AUTHOR]

Abstract The black‐footed cat (Felis nigripes) is endemic to the arid regions of southern Africa. One of the world's smallest wild felids, the species occurs at low densities and is secretive and elusive, which makes ecological studies difficult. Genetic data could provide key information such as estimates on population size, sex ratios, and genetic diversity. In this study, we test if microsatellite loci can be successfully amplified from scat samples that could be noninvasively collected from the field. Using 21 blood and scat samples collected from the same individuals, we statistically tested whether nine microsatellites previously designed for use in domestic cats can be used to identify individual black‐footed cats. Genotypes recovered from blood and scat samples were compared to assess loss of heterozygosity, allele dropout, and false alleles resulting from DNA degradation or PCR inhibitors present in scat samples. The microsatellite markers were also used to identify individuals from scats collected in the field that were not linked to any blood samples. All nine microsatellites used in this study were amplified successfully and were polymorphic. Microsatellite loci were found to have sufficient discriminatory power to distinguish individuals and identify clones. In conclusion, these molecular markers can be used to monitor populations of wild black‐footed cats noninvasively. The genetic data will be able to contribute important information that may be used to guide future conservation initiatives.

Moreover, 6 and 25 genes encoding DNA methyltransferase and demethylation-related factors, respectively, were identified in the peach genome (Table S12), but they all had similar expression in fruits at 31 DAFB between "ZY4" and "LXH". A large-scale behavior of allelic dropout and imbalance caused by DNA methylation changes in an early-ripening bud sport of peach Since DNA methylation is one of the main reasons for ASE (Satyaki & Gehring, [17]; da Rocha & Gendrel, [16]), DNA methylation patterns in fruits of "ZY4" and "LXH" were investigated using Whole Genome Bisulfite Sequencing (WGBS). Keywords: allelic dropout; allelic imbalance; bud sport; DNA methylation; Prunus persica EN allelic dropout allelic imbalance bud sport DNA methylation Prunus persica 13 18 6 06/05/23 20230701 NES 230701 Data availability The sequencing data generated in this study have been deposited in NCBI SRA database with the Bio-Project accession number: PRJNA939397. [Extracted from the article]

Context Genetic testing is useful not only for the diagnosis of the MEN1 proband but also for determining the putative asymptomatic variant carriers to improve the prognosis or to avoid unnecessary medical intervention. However, we must be aware of the putative pitfalls of polymerase chain reaction (PCR)-based genetic testing in specific conditions that lead to medical mismanagement. Objective To warn of the putative pitfalls of PCR-based genetic testing, we report an overlooked case of MEN1 due to PCR allelic dropout. Methods A 69-year-old man was clinically diagnosed with MEN1, and genetic testing revealed that he had a pathogenic variant in the MEN1 gene. His 36-year-old son was completely asymptomatic. As the son was 50% at risk of MEN1, he was willing to undergo genetic testing himself after genetic counseling. Results Genetic testing was carried out in 2 independent laboratories. Although laboratory A showed that he carried a pathogenic variant, laboratory B showed that he had the wild-type genotype of MEN1. The discrepancy in these results was due to PCR allelic dropout by single-nucleotide variations of the MEN1 gene in the 5′ region. The surveillance revealed that he had asymptomatic primary hyperparathyroidism and a neuroendocrine tumor of the pancreas. Conclusion PCR-dependent genetic analysis may be susceptible to PCR allelic dropout in an SNV-specific manner. We must be careful when genetically testing individuals of relatives with clinical MEN1 disease. [ABSTRACT FROM AUTHOR]

Aim: The aim of this study is to investigate if Preimplantation Genetic Testing (PGT) can effectively identify unreported variants according to American College of Medical Genetics and Genomics (ACMG)to prevent citrullinemia type 1 affection., Design: This study involves a detailed case analysis of a family with history of citrullinemia type 1, focusing on the use of PGT for monogenic diseases (PGT-M). The genetic variants were identified using ACMG guidelines, and PGT was employed to prevent the inheritance of these variants. The study included haplotype analysis and Sanger sequencing to confirm the results., Results: The study identified previously unreported variations in the ASS1 gene causing citrullinemia type 1. PGT successfully prevented the transmission of these variants, resulting in the birth of a healthy fetus. However, challenges such as allele dropout (ADO) and gene recombination were encountered during haplotype analysis, which could potentially defeat the diagnosis. The study demonstrated that combining haplotype analysis with Sanger sequencing can enhance the accuracy of PGT., Conclusion: Preimplantation Genetic Testing (PGT) targeting likely pathogenic and pathogenic variants in the ASS1 gene, as rated by ACMG, allows the birth of healthy infants free from citrullinemia type 1. Additionally, the establishment of single haplotypes and Sanger sequencing can reduce the misdiagnosis rate caused by allele dropout (ADO) and genetic recombination., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Wu, Liang, Liu, Ding and Shu.)

Primary cardiomyopathies (CMPs) are monogenic but multi-allelic disorders with dozens of genes involved in pathogenesis. The implementation of next-generation sequencing (NGS) approaches has resulted in more time- and cost-efficient DNA diagnostics of cardiomyopathies. However, the diagnostic yield of genetic testing for each subtype of CMP fails to exceed 60%. The aim of this study was to demonstrate that allelic dropout (ADO) is a common phenomenon that reduces the diagnostic yield in primary cardiomyopathy genetic testing based on targeted gene panels assayed on the Ion Torrent platform. We performed mutational screening with three custom targeted gene panels based on sets of oligoprimers designed automatically using AmpliSeq Designer® containing 1049 primer pairs for 37 genes with a total length of 153 kb. DNA samples from 232 patients were screened with at least one of these targeted gene panels. We detected six ADO events in both IonTorrent PGM (three cases) and capillary Sanger sequencing (three cases) data, identifying ADO-causing variants in all cases. All ADO events occurred due to common or rare single nucleotide variants (SNVs) in the oligoprimer binding sites and were detected because of the presence of “marker” SNVs in the target DNA fragment. We ultimately identified that PCR-based NGS involves a risk of ADO that necessitates the use of Sanger sequencing to validate NGS results. We assume that oligoprimer design without ADO data affects the amplification efficiency of up to 0.77% of amplicons.

Primary cardiomyopathies (CMPs) are monogenic but multi-allelic disorders with dozens of genes involved in pathogenesis. The implementation of next-generation sequencing (NGS) approaches has resulted in more time- and cost-efficient DNA diagnostics of cardiomyopathies. However, the diagnostic yield of genetic testing for each subtype of CMP fails to exceed 60%. The aim of this study was to demonstrate that allelic dropout (ADO) is a common phenomenon that reduces the diagnostic yield in primary cardiomyopathy genetic testing based on targeted gene panels assayed on the Ion Torrent platform. We performed mutational screening with three custom targeted gene panels based on sets of oligoprimers designed automatically using AmpliSeq Designer® containing 1049 primer pairs for 37 genes with a total length of 153 kb. DNA samples from 232 patients were screened with at least one of these targeted gene panels. We detected six ADO events in both IonTorrent PGM (three cases) and capillary Sanger sequencing (three cases) data, identifying ADO-causing variants in all cases. All ADO events occurred due to common or rare single nucleotide variants (SNVs) in the oligoprimer binding sites and were detected because of the presence of "marker" SNVs in the target DNA fragment. We ultimately identified that PCR-based NGS involves a risk of ADO that necessitates the use of Sanger sequencing to validate NGS results. We assume that oligoprimer design without ADO data affects the amplification efficiency of up to 0.77% of amplicons. [ABSTRACT FROM AUTHOR]

Loss of one allele during polymerase chain reaction (PCR) amplification of DNA, known as allelic dropout, can be caused by a variety of mechanisms. Allelic dropout during PCR may have profound implications for molecular diagnostic and research procedures that depend on PCR and assume biallelic amplification has occurred. Complete allelic dropout due to the combined effects of cytosine methylation and G-quadruplex formation was previously described for a differentially methylated region of the human imprinted gene, MEST. We now demonstrate that this parent-of-origin specific allelic dropout can potentially occur at several other genomic regions that display genomic imprinting and have propensity for G-quadruplex formation, including AIM1, BLCAP, DNMT1, PLAGL1, KCNQ1, and GRB10. These findings demonstrate that systematic allelic dropout during PCR is a general phenomenon for regions of the genome where differential allelic methylation and G-quadruplex motifs coincide, and suggest that great care must be taken to ensure biallelic amplification is occurring in such situations.

High-throughput sequencing methods that multiplex a large number of individuals have provided a cost-effective approach for discovering genome-wide genetic variation in large populations. These sequencing methods are increasingly being utilized in population genetic studies across a diverse range of species. Two side-effects of these methods, however, are (1) sequencing errors and (2) heterozygous genotypes called as homozygous due to only one allele at a particular locus being sequenced, which occurs when the sequencing depth is insufficient. Both of these errors have a profound effect on the estimation of linkage disequilibrium (LD) and, if not taken into account, lead to inaccurate estimates. We developed a new likelihood method, GUS-LD, to estimate pairwise linkage disequilibrium using low coverage sequencing data that accounts for undercalled heterozygous genotypes and sequencing errors. Our findings show that accurate estimates were obtained using GUS-LD, whereas underestimation of LD results if no adjustment is made for the errors. [ABSTRACT FROM AUTHOR]

Loss of one allele during polymerase chain reaction (PCR) amplification of DNA, known as allelic dropout, can be caused by a variety of mechanisms. Allelic dropout during PCR may have profound implications for molecular diagnostic and research procedures that depend on PCR and assume biallelic amplification has occurred. Complete allelic dropout due to the combined effects of cytosine methylation and G-quadruplex formation was previously described for a differentially methylated region of the human imprinted gene, MEST. We now demonstrate that this parent-of-origin specific allelic dropout can potentially occur at several other genomic regions that display genomic imprinting and have propensity for G-quadruplex formation, including AIM1, BLCAP, DNMT1, PLAGL1, KCNQ1, and GRB10. These findings demonstrate that systematic allelic dropout during PCR is a general phenomenon for regions of the genome where differential allelic methylation and G-quadruplex motifs coincide, and suggest that great care must be taken to ensure biallelic amplification is occurring in such situations. [ABSTRACT FROM AUTHOR]

Microsatellite genetic marker data are exploited in a variety of fields, including forensics, gene mapping, kinship inference and population genetics. In all of these fields, inference can be thwarted by failure to quantify and account for data errors, and kinship inference in particular can benefit from separating errors into two distinct classes: allelic dropout and false alleles. Pedant is MS Windows software for estimating locus-specific maximum likelihood rates of these two classes of error. Estimation is based on comparison of duplicate error-prone genotypes: neither reference genotypes nor pedigree data are required. Other functions include: plotting of error rate estimates and confidence intervals; simulations for performing power analysis and for testing the robustness of error rate estimates to violation of the underlying assumptions; and estimation of expected heterozygosity, which is a required input. The program, documentation and source code are available from http://www.stats.gla.ac.uk/~paulj/pedant.html.

Background: The Major Histocompatibility Complex (MHC) is the most important genetic marker to study patterns of adaptive genetic variation determining pathogen resistance and associated life history decisions. It is used in many different research fields ranging from human medical, molecular evolutionary to functional biodiversity studies. Correct assessment of the individual allelic diversity pattern and the underlying structural sequence variation is the basic requirement to address the functional importance of MHC variability. Next-generation sequencing (NGS) technologies are likely to replace traditional genotyping methods to a great extent in the near future but first empirical studies strongly indicate the need for a rigorous quality control pipeline. Strict approaches for data validation and allele calling to distinguish true alleles from artefacts are required. Results: We developed the analytical methodology and validated a data processing procedure which can be applied to any organism. It allows the separation of true alleles from artefacts and the evaluation of genotyping reliability, which in addition to artefacts considers for the first time the possibility of allelic dropout due to unbalanced amplification efficiencies across alleles. Finally, we developed a method to assess the confidence level per genotype a-posteriori, which helps to decide which alleles and individuals should be included in any further downstream analyses. The latter method could also be used for optimizing experiment designs in the future. Conclusions: Combining our workflow with the study of amplification efficiency offers the chance for researchers to evaluate enormous amounts of NGS-generated data in great detail, improving confidence over the downstream analyses and subsequent applications. [ABSTRACT FROM AUTHOR]

Context: Genetic testing is useful not only for the diagnosis of the MEN1 proband but also for determining the putative asymptomatic variant carriers to improve the prognosis or to avoid unnecessary medical intervention. However, we must be aware of the putative pitfalls of polymerase chain reaction (PCR)-based genetic testing in specific conditions that lead to medical mismanagement., Objective: To warn of the putative pitfalls of PCR-based genetic testing, we report an overlooked case of MEN1 due to PCR allelic dropout., Methods: A 69-year-old man was clinically diagnosed with MEN1, and genetic testing revealed that he had a pathogenic variant in the MEN1 gene. His 36-year-old son was completely asymptomatic. As the son was 50% at risk of MEN1, he was willing to undergo genetic testing himself after genetic counseling., Results: Genetic testing was carried out in 2 independent laboratories. Although laboratory A showed that he carried a pathogenic variant, laboratory B showed that he had the wild-type genotype of MEN1 . The discrepancy in these results was due to PCR allelic dropout by single-nucleotide variations of the MEN1 gene in the 5' region. The surveillance revealed that he had asymptomatic primary hyperparathyroidism and a neuroendocrine tumor of the pancreas., Conclusion: PCR-dependent genetic analysis may be susceptible to PCR allelic dropout in an SNV-specific manner. We must be careful when genetically testing individuals of relatives with clinical MEN1 disease., (© The Author(s) 2022. Published by Oxford University Press on behalf of the Endocrine Society.)

Optimal collection and preservation protocols for fecal DNA genotyping are not firmly established. We evaluated 3 factors that influence microsatellite genotyping success of fecal DNA extracted from coyote (Canis latrans) scats: 1) age of scat, 2) preservative, and 3) diet content. We quantified genotyping success by comparing rates of allelic dropout, false alleles, and failed amplifications among consensus genotypes. We used a panel of 6 microsatellite loci to genotype 20 scat samples, each of which was subjected to 3 age (1 day, 5 days, and 10 days post-deposition) and 3 preservation (DET buffer, 95% ethanol [EtOH], and lysis buffer) treatments. Both sample age and storage buffer had a significant effect on success and reliability. Ethanol and DET buffer preserved fecal samples with similar efficiency, and both were superior to lysis buffer. Our analysis of DNA degradation rates revealed that samples collected as early as 5 days of age yielded DNA that was highly degraded relative to samples collected on day 1. We tested the influence of dietary remains on microsatellite genotyping by using scat samples consisting predominantly of insect prey (n = 5), mammalian prey (n = 9), or the remains of juniper (Juniperus spp.) berries (n = 6) and compared EtOH and DET buffer preservation efficacy. We observed a significant interaction effect between storage buffer and diet for the probability of a false allele in a polymerase chain reaction (PCR), suggesting that the optimal preservation technique depended on the food remains comprising the scat. Scats comprised of juniper berry remains were more reliably genotyped when preserved in DET than EtOH. Mammalian prey-based scats were more reliable when stored in EtOH than DET buffer. Insect-predominant scats were preserved in EtOH and DET buffer with similar efficiency. Although accurate and reliable results can be obtained from scats collected at =5 days of age, we suggest sampling design to include collection of scats <5 days of age to minimize field and laboratory expenses. We suggest EtOH preservation for scats of obligate carnivores and of facultative carnivores with a diet consisting primarily of mammals. We suggest DET buffer preservation for animals with a diet consisting of plant-derived foods. Lysis buffer protocols that we employed should not be used for fecal DNA preservation. [ABSTRACT FROM AUTHOR]

Sampling of feces for genetic studies of wild populations can be problematic because of the low quality and quantity of template DNA obtained. We used cotton swabs in the field to isolate the mucous layer on the surface of fresh wolf (Canis lupus, C. lycaon, and their hybrids) scats followed by immediate preservation, and compared microsatellite genotyping of DNA from these fresh field swabs (FS) to that of previously frozen laboratory swabs (LS). In single polymerase chain reactions (PCRs) of 2 multiplexes, amplification at 8 loci was higher in the FS samples (FS = 50%, LS = 15%; P 5 0.02) because proportion, quantity, and quality of large fragment wolf nuclear DNA from these samples was greater (2.5-25%, 6.25-62.5 ng/swab, 35% amplified at 1,000 base pairs [bp]) than from the LS samples (1.9%-10%, 4.7-25 ng/ swab, 10% amplified at 1,000 bp). Paired blood and fresh field-swabbed samples had identical genotypes. In 84 multiplex PCRs we found no evidence of allelic dropout associated with low template quality or quantity. We conclude that field swabbing of fresh wolf scat facilitates field storage and reduces the need for multiple amplifications at single microsatellite loci, thereby reducing the genotyping costs for wildlife projects that use noninvasive samples. [ABSTRACT FROM AUTHOR]

Sampling DNA noninvasively has advantages for identifying animals for uses such as mark–recapture modeling that require unique identification of animals in samples. Although it is possible to generate large amounts of data from noninvasive sources of DNA, a challenge is overcoming genotyping errors that can lead to incorrect identification of individuals. A major source of error is allelic dropout, which is failure of DNA amplification at one or more loci. This has the effect of heterozygous individuals being scored as homozygotes at those loci as only one allele is detected. If errors go undetected and the genotypes are naively used in mark–recapture models, significant overestimates of population size can occur. To avoid this it is common to reject low-quality samples but this may lead to the elimination of large amounts of data. It is preferable to retain these low-quality samples as they still contain usable information in the form of partial genotypes. Rather than trying to minimize error or discarding error-prone samples we model dropout in our analysis. We describe a method based on data augmentation that allows us to model data from samples that include uncertain genotypes. Application is illustrated using data from the European badger ( Meles meles). [ABSTRACT FROM AUTHOR]

Abstract: A method is suggested that allows the use of loci that have shown allelic dropout in kinship analysis as used for disaster victim identification (DVI) and missing person work (MP). This approach uses an extension of a previously published approach to modelling allelic dropout. This method may salvage some information in cases where allelic dropout is hindering DVI or MP work particularly in reconciliations involving a large number of bodies and pedigrees. It should not replace the pursuit of more complete DNA profiles by the normal rework process for such samples. [Copyright &y& Elsevier]

Abstract: The 2p rule is commonly used to interpret partial DNA profiles where dropout may have occurred. Recently this approach has been questioned in court. We investigate the performance of this rule, and give conditions under which it may be relied upon. Our analysis leads us to recommend an alternative approach. This may be used in all circumstances or reserved for those circumstances under which the 2p rule is not conservative. [Copyright &y& Elsevier]

Background: Whole genome amplification (WGA) is required for single cell genotyping. Effectiveness of currently available WGA technologies in combination with next generation sequencing (NGS) and material preservation is still elusive., Results: In respect to the accuracy of SNP/mutation, indel, and copy number aberrations (CNA) calling, the HiSeq2000 platform outperformed IonProton in all aspects. Furthermore, more accurate SNP/mutation and indel calling was demonstrated using single tumor cells obtained from EDTA-collected blood in respect to CellSave-preserved blood, whereas CNA analysis in our study was not detectably affected by fixation. Although MDA-based WGA yielded the highest DNA amount, DNA quality was not adequate for downstream analysis. PCR-based WGA demonstrates superiority over MDA-PCR combining technique for SNP and indel analysis in single cells. However, SNP calling performance of MDA-PCR WGA improves with increasing amount of input DNA, whereas CNA analysis does not. The performance of PCR-based WGA did not significantly improve with increase of input material. CNA profiles of single cells, amplified with MDA-PCR technique and sequenced on both HiSeq2000 and IonProton platforms, resembled unamplified DNA the most., Materials and Methods: We analyzed the performance of PCR-based, multiple-displacement amplification (MDA)-based, and MDA-PCR combining WGA techniques (WGA kits Ampli1, REPLI-g, and PicoPlex, respectively) on single and pooled tumor cells obtained from EDTA- and CellSave-preserved blood and archival material. Amplified DNA underwent exome-Seq with the Illumina HiSeq2000 and ThermoFisher IonProton platforms., Conclusion: We demonstrate the feasibility of single cell genotyping of differently preserved material, nevertheless, WGA and NGS approaches have to be chosen carefully depending on the study aims., Competing Interests: CONFLICTS OF INTEREST Anna Babayan, Malik Alawi, Volkmar Müller, Harriet Wikman, Maria Geffken, and Simon A Joosse have no conflicts or disclosures to report. Michael Gormley: employed by Johnson and Johnson. Ryan P. McMullin: employed by LabConnect LLC through contract with Janssen R&D. No other conflicts or disclosures. Denis A. Smirnov: employed by Johnson and Johnson. No other conflicts or disclosures. Weimin Li: employed by Johnson and Johnson and is shareholder. Klaus Pantel: received a research grant from Janssen R&D.

Microsatellite genetic marker data are exploited in a variety of fields, including forensics, gene mapping, kinship inference and population genetics. In all of these fields, inference can be thwarted by failure to quantify and account for data errors, and kinship inference in particular can benefit from separating errors into two distinct classes: allelic dropout and false alleles. Pedant is MS Windows software for estimating locus-specific maximum likelihood rates of these two classes of error. Estimation is based on comparison of duplicate error-prone genotypes: neither reference genotypes nor pedigree data are required. Other functions include: plotting of error rate estimates and confidence intervals; simulations for performing power analysis and for testing the robustness of error rate estimates to violation of the underlying assumptions; and estimation of expected heterozygosity, which is a required input. The program, documentation and source code are available from http://www.stats.gla.ac.uk/~paulj/pedant.html.