HPV genotyping in clinical samples using long-read single-molecule real-time sequencing.

Human papillomavirus (HPV) genotyping is widely used, particularly in combination with high-risk (HR) HPV tests for cervical cancer screening. We developed a genotyping method using sequences of approximately 800 bp in the E6/E7 region obtained by PacBio single molecule real-time sequencing (SMRT) and evaluated its performance against MY09-11 L1 sequencing and after the APTIMA HPV genotyping assay. The levels of concordance of PacBio E6/E7 SMRT sequencing with MY09-11 L1 sequencing and APTIMA HPV genotyping were 100% and 90.8%, respectively. The sensitivity of PacBio E6/EA7 SMRT was slightly greater than that of L1 sequencing and, as expected, lower than that of HR-HPV tests. In the context of cervical cancer screening, PacBio E6/E7 SMRT is then best used after a positive HPV test. PacBio E6/E7 SMRT genotyping is an attractive alternative for HR and LR-HPV genotyping of clinical samples. PacBio SMRT sequencing provides unbiased genotyping and can detect multiple HPV infections and haplotypes within a genotype.

Development and verification of a 10K liquid chip for Hainan black goat based on genotyping by pinpoint sequencing of liquid captured targets.

BACKGROUND: China has thousands years of goat breeding and abundant goat genetic resources. Additionally, the Hainan black goat is one of the high-quality local goat breeds in China. In order to conserve the germplasm resources of the Hainan black goat, facilitate its genetic improvement and further protect the genetic diversity of goats, it is urgent to develop a single nucleotide polymorphism (SNP) chip for Hainan black goat. RESULTS: In this study, we aimed to design a 10K liquid chip for Hainan black goat based on genotyping by pinpoint sequencing of liquid captured targets (cGPS). A total of 45,588 candidate SNP sites were obtained, 10,677 of which representative SNP sites were selected to design probes, which finally covered 9,993 intervals and formed a 10K cGPS liquid chip for Hainan black goat. To verify the 10K cGPS liquid chip, some southern Chinese goat breeds and a sheep breed with similar phenotype to the Hainan black goat were selected. A total of 104 samples were used to verify the clustering ability of the 10K cGPS liquid chip for Hainan black goat. The results showed that the detection rate of sites was 97.34% -99.93%. 84.5% of SNP sites were polymorphic. The heterozygosity rate was 3.08%-36.80%. The depth of more than 99.4% sites was above 10X. The repetition rate was 99.66%-99.82%. The average consistency between cGPS liquid chip results and resequencing results was 85.58%. In addition, the phylogenetic tree clustering analysis verified that the SNP sites on the chip had better clustering ability. CONCLUSION: These results indicate that we have successfully realized the development and verification of the 10K cGPS liquid chip for Hainan black goat, which provides a useful tool for the genome analysis of Hainan black goat. Moreover, the 10K cGPS liquid chip is conducive to the research and protection of Hainan black goat germplasm resources and lays a solid foundation for its subsequent breeding work.

Unveiling Discrepant and Rare Dihydropyrimidine Dehydrogenase (DPYD) Results Using an In-House Genotyping Test: A Case Series.

Fluoropyrimidine chemotherapy is a primary component of many solid tumor treatment regimens, particularly those for gastrointestinal malignancies. Approximately one-third of patients receiving fluoropyrimidine-based chemotherapies experience serious adverse effects. This risk is substantially higher in patients carrying DPYD genetic variants, which cause reduced fluoropyrimidine metabolism and inactivation (ie, dihydropyridine dehydrogenase [DPD] deficiency). Despite the known relationship between DPD deficiency and severe toxicity risk, including drug-related fatalities, pretreatment DPYD testing is not standard of care in the United States. We developed an in-house DPYD genotyping test that detects 5 clinically actionable variants associated with DPD deficiency, and genotyped 827 patients receiving fluoropyrimidines, of which 49 (6%) were identified as heterozygous carriers. We highlight 3 unique cases: (1) a patient with a false-negative result from a commercial laboratory that only tested for the c.1905 + 1G>A (*2A) variant, (2) a White patient in whom the c.557A>G variant (typically observed in people of African ancestry) was detected, and (3) a patient with the rare c.1679T>G (*13) variant. Lastly, we evaluated which DPYD variants are detected by commercial laboratories offering DPYD genotyping in the United States and found 6 of 13 (46%) did not test for all 5 variants included on our panel. We estimated that 20.4% to 81.6% of DPYD heterozygous carriers identified on our panel would have had a false-negative result if tested by 1 of these 6 laboratories. The sensitivity and negative predictive value of the diagnostic tests from these laboratories ranged from 18.4% to 79.6% and 95.1% to 98.7%, respectively. These cases underscore the importance of comprehensive DPYD genotyping to accurately identify patients with DPD deficiency who may require lower fluoropyrimidine doses to mitigate severe toxicities and hospitalizations. Clinicians should be aware of test limitations and variability in variant detection by commercial laboratories, and seek assistance by pharmacogenetic experts or available resources for test selection and result interpretation.

Major chromosome rearrangements in intergeneric wheat × rye hybrids in compatible and incompatible crosses detected by GBS read coverage analysis.

The presence of incompatibility alleles in primary amphidiploids constitutes a reproductive barrier in newly synthesized wheat-rye hybrids. To overcome this barrier, the genome stabilization process includes large-scale chromosome rearrangements. In incompatible crosses resulting in fertile amphidiploids, the elimination of one of the incompatible alleles Eml-A1 or Eml-R1b can occur already in the somatic tissue of the wheat × rye hybrid embryo. We observed that the interaction of incompatible loci Eml-A1 of wheat and Eml-R1b of rye after overcoming embryo lethality leads to hybrid sterility in primary triticale. During subsequent seed reproductions (R1, R2 or R3) most of the chromosomes of A, B, D and R subgenomes undergo rearrangement or eliminations to increase the fertility of the amphidiploid by natural selection. Genotyping-by-sequencing (GBS) coverage analysis showed that improved fertility is associated with the elimination of entire and partial chromosomes carrying factors that either cause the disruption of plant development in hybrid plants or lead to the restoration of the euploid number of chromosomes (2n = 56) in the absence of one of the incompatible alleles. Highly fertile offspring obtained in compatible and incompatible crosses can be successfully adapted for the production of triticale pre-breeding stocks.

Development of a DNA-Based Lateral Flow Strip Membrane Assay for Rapid Screening and Genotyping of Six High-Incidence STD Pathogens.

Sexually transmitted diseases (STDs) are a global concern because approximately 1 million new cases emerge daily. Most STDs are curable, but if left untreated, they can cause severe long-term health implications, including infertility and even death. Therefore, a test enabling rapid and accurate screening and genotyping of STD pathogens is highly awaited. Herein, we present the development of the DNA-based 6STD Genotyping 9G Membrane test, a lateral flow strip membrane assay, for the detection and genotyping of six STD pathogens, including Trichomonas vaginalis, Ureaplasma urealyticum, Neisseria gonorrhoeae, Chlamydia trachomatis, Mycoplasma hominis, and Mycoplasma genitalium. Here, we developed a multiplex PCR primer set that allows PCR amplification of genomic materials for these six STD pathogens. We also developed the six ssDNA probes that allow highly efficient detection of the six STD pathogens. The 6STD Genotyping 9G Membrane test lets us obtain the final detection and genotyping results in less than 30 m after PCR at 25 °C. The accuracy of the 6STD Genotyping 9G membrane test in STD genotyping was confirmed by its 100% concordance with the sequencing results of 120 clinical samples. Therefore, the 6STD Genotyping 9G Membrane test emerges as a promising diagnostic tool for precise STD genotyping, facilitating informed decision-making in clinical practice.

Genotyping-by-sequencing and weighted gene co-expression network analysis of genes responsive against Potato virus Y in commercial potato cultivars.

Potato is considered a key component of the global food system and plays a vital role in strengthening world food security. A major constraint to potato production worldwide is the Potato Virus Y (PVY), belonging to the genus Potyvirus in the family of Potyviridae. Selective breeding of potato with resistance to PVY pathogens remains the best method to limit the impact of viral infections. Understanding the genetic diversity and population structure of potato germplasm is important for breeders to improve new cultivars for the sustainable use of genetic materials in potato breeding to PVY pathogens. While, genetic diversity improvement in modern potato breeding is facing increasingly narrow genetic basis and the decline of the genetic diversity. In this research, we performed genotyping-by-sequencing (GBS)-based diversity analysis on 10 commercial potato cultivars and weighted gene co-expression network analysis (WGCNA) to identify candidate genes related to PVY-resistance. WGCNA is a system biology technique that uses the WGCNA R software package to describe the correlation patterns between genes in multiple samples. In terms of consumption, these cultivars are a high rate among Iranian people. Using population structure analysis, the 10 cultivars were clustered into three groups based on the 118343 single nucleotide polymorphisms (SNPs) generated by GBS. Read depth ranged between 5 and 18. The average data size and Q30 of the reads were 145.98 Mb and 93.63%, respectively. Based on the WGCNA and gene expression analysis, the StDUF538, StGTF3C5, and StTMEM161A genes were associated with PVY resistance in the potato genome. Further, these three hub genes were significantly involved in defense mechanism where the StTMEM161A was involved in the regulation of alkalization apoplast, the StDUF538 was activated in the chloroplast degradation program, and the StGTF3C5 regulated the proteins increase related to defense in the PVY infected cells. In addition, in the genetic improvement programs, these hub genes can be used as genetic markers for screening commercial cultivars for PVY resistance. Our survey demonstrated that the combination of GBS-based genetic diversity germplasm analysis and WGCNA can assist breeders to select cultivars resistant to PVY as well as help design proper crossing schemes in potato breeding.

Comparison of diagnostic performance among Abbott RealTime HCV Genotyping II, Abbott HCV Genotype plus RUO, and Roche Cobas HCV Genotyping assays for hepatitis C virus genotyping.

Comparison of diagnostic accuracy for commercial hepatitis C virus (HCV) genotyping (Abbott RealTime HCV Genotyping II, Roche Cobas Genotyping) and investigational Abbott HCV Genotype plus RUO assays designed to discriminate genotype (GT)-1a, 1b or 6 in cases of ambiguous GT from the Abbott commercial assay remains limited. 743 HCV-viremic samples were subjected to analysis using Abbott and Roche commercial as well as Abbott HCV Genotype plus RUO assays. Next-generation sequencing (NGS) targeting core region was employed as the reference standard. Diagnostic accuracy was reported as the number of participants (percentages) along with 95% confidence intervals (CIs). Using NGS, 741 samples (99.7%) yielded valid genotyping results. The diagnostic accuracies were 97.6% (95% CI: 96.1%-98.5%) and 95.3% (95% CI: 93.4%-96.6%) using Abbott and Roche commercial assays (p = 0.0174). Abbott commercial assay accurately diagnosed HCV GT-6a and 6w, whereas Roche commercial assay accurately diagnosed HCV GT-6a. Both assays demonstrated low accuracies for HCV GT-6b, 6e, 6g, and 6n. Abbott HCV Genotype plus RUO assay discriminated 13 of the 14 samples (92.9%; 95% CI: 64.2%-99.6%) that yielded ambiguous GT. Both assays were capable of diagnosing mixed HCV infections when the minor genotype comprised >8.4% of the viral load. The diagnostic performance of commercial HCV genotyping assays is commendable. Abbott assay demonstrated superior performance compared to Roche assay in diagnosing HCV GT-6. Abbott HCV Genotype plus RUO assay aids in discriminating ambiguous GT. Both commercial assays are proficient in diagnosing mixed HCV infections at a cut-off viral load of 8.4% in minor genotype.

Mating type and microsatellite genotyping indicate that the Tunisian population of Phyllosticta citricarpa is clonal and thrives only asexually.

Citrus black spot (CBS) caused by Phyllosticta citricarpa was reported for the first time in Tunisia in 2019. This was also the first reported occurrence of the disease in a Mediterranean climate. In Tunisia, CBS is mainly found in lemon (Citrus limon) orchards, and is seldom observed on sweet orange (Citrus × sinensis). This recent finding in North Africa raises questions about how the disease has been able to spread under Mediterranean climatic conditions. In this work, 216 Phyllosticta strains collected from lemon orchards in 2021, 2022 and 2023 throughout the country's main citrus-growing provinces were characterised by species morphological and molecular identification, mating type and Simple Sequence Repeats (SSR) microsatellite genotyping (MLG). P. citricarpa was the only species found to be associated with CBS in Tunisia. Although P. citricarpa is a heterothallic fungal species, potentially able to reproduce both sexually and asexually, a single mating type (MAT 1-1-1) idiomorph was found in the population. In addition, three MLGs were observed, across ten microsatellite loci, one of which was massively represented (93 %), indicating a clonal population. The clonality observed suggests a single recent introduction of the pathogen into the country. These findings support the idea that in Tunisia, P. citricarpa only reproduces asexually by pycniospores, with a relatively limited dispersal potential. This is consistent with the absence of pseudothecia on the leaf litter. These results show that CBS is able to thrive under Mediterranean conditions, even in the absence of sexual reproduction. This should be taken into consideration for CBS risk assessment and management.

Mapping genotypes to chromatin accessibility profiles in single cells.

In somatic tissue differentiation, chromatin accessibility changes govern priming and precursor commitment towards cellular fates1-3. Therefore, somatic mutations are likely to alter chromatin accessibility patterns, as they disrupt differentiation topologies leading to abnormal clonal outgrowth. However, defining the impact of somatic mutations on the epigenome in human samples is challenging due to admixed mutated and wild-type cells. Here, to chart how somatic mutations disrupt epigenetic landscapes in human clonal outgrowths, we developed genotyping of targeted loci with single-cell chromatin accessibility (GoT-ChA). This high-throughput platform links genotypes to chromatin accessibility at single-cell resolution across thousands of cells within a single assay. We applied GoT-ChA to CD34+ cells from patients with myeloproliferative neoplasms with JAK2V617F-mutated haematopoiesis. Differential accessibility analysis between wild-type and JAK2V617F-mutant progenitors revealed both cell-intrinsic and cell-state-specific shifts within mutant haematopoietic precursors, including cell-intrinsic pro-inflammatory signatures in haematopoietic stem cells, and a distinct profibrotic inflammatory chromatin landscape in megakaryocytic progenitors. Integration of mitochondrial genome profiling and cell-surface protein expression measurement allowed expansion of genotyping onto DOGMA-seq through imputation, enabling single-cell capture of genotypes, chromatin accessibility, RNA expression and cell-surface protein expression. Collectively, we show that the JAK2V617F mutation leads to epigenetic rewiring in a cell-intrinsic and cell type-specific manner, influencing inflammation states and differentiation trajectories. We envision that GoT-ChA will empower broad future investigations of the critical link between somatic mutations and epigenetic alterations across clonal populations in malignant and non-malignant contexts.

High-resolution HLA genotyping improves PIRCHE-II assessment of molecular mismatching in kidney transplantation.

HLA matching in solid organ transplant is performed with the aim of assessing immunologic compatibility in order to avoid hyperacute rejection and assess the risk of future rejection events. Molecular mismatch algorithms are intended to improve granularity in histocompatibility assessment and risk stratification. PIRCHE-II uses HLA genotyping to predict indirectly presented mismatched donor HLA peptides, though most clinical validation studies rely on imputing high resolution (HR) genotypes from low resolution (LR) typing data. We hypothesized that use of bona fide HR typing could overcome limitations in imputation, improving accuracy and predictive ability for donor-specific antibody development and acute rejection. We performed a retrospective analysis of adult and pediatric kidney transplant donor/recipient pairs (N = 419) with HR typing and compared the use of imputed LR genotyping verses HR genotyping for PIRCHE-II analysis and outcomes. Imputation success was highly dependent on the reference population used, as using historic Caucasian reference populations resulted in 10 % of pairs with unsuccessful imputation while multiethnic reference populations improved successful imputation with only 1 % unable to be imputed. Comparing PIRCHE-II analysis with HR and LR genotyping produced notably different results, with 20 % of patients discrepantly classified to immunologic risk groups. These data emphasize the importance of using multiethnic reference panels when performing imputation and indicate HR HLA genotyping has clinically meaningful benefit for PIRCHE-II analysis compared to imputed LR typing.

Single-tube Ptprc SNP genotyping of JAXBoy (CD45.1) and C57BL/6J (CD45.2) mice by endpoint PCR and gel electrophoresis.

Allelic variation at the Ptprc gene, which encodes the pan-leukocyte marker CD45/Ly5, is commonly exploited to track hematopoietic reconstitution by flow cytometry in mixed bone marrow chimera transplant experiments. Historically, this was accomplished using bone marrow from C57BL/6 (Ptprcb/CD45.2/Ly5.2) and congenic B6.SJL-PtprcaPepcb/Boy (Ptprca/CD45.1/Ly5.1) mice. Recently, the Jackson Laboratory directly CRISPR-engineered the Ptprca allele in C57BL/6J mice. This new isogenic strain, termed JAXBoy, differs from wild-type C57BL/6J mice by two nucleotides, compared to the biologically significant 37 megabase (Mb) SJL interval retained in B6.SJL-PtprcaPepcb/Boy/J mice. Currently, Ptprc/CD45 variants are identified by flow cytometry or allele-specific real-time PCR, both of which require specialized workflows and equipment compared to standard genotyping of endpoint PCR products by gel electrophoresis. Here, we employed allele-specific oligonucleotides in conjunction with differential incorporation of a long non-specific oligo 5'-tail to allow for simultaneous identification of the Ptprca and Ptprcb alleles using endpoint PCR and gel electrophoresis. This method allows for integration of Ptprc genotyping into standard genotyping workflows, which use a single set of thermocycling and gel electrophoresis conditions. Importantly, the strategy of primer placement and tail addition described here can be adapted to discriminate similar single- or multi-nucleotide polymorphisms at other genomic loci.

RHC genotyping in Chinese Han population.

BACKGROUND: The Rh blood group system is characterized by its complexity and polymorphism, encompassing 56 different antigens. Accurately predicting the presence of the C antigen using genotyping methods has been challenging. The objective of this study was to evaluate the accuracy of various genotyping methods for predicting the Rh C and to identify a suitable method for the Chinese Han population. METHODS: In total, 317 donors, consisting 223 D+ (including 20 with the Del phenotype) and 94 D- were randomly selected. For RHC genotyping, 48C and 109bp insertion were detected on the Real-time PCR platform and -292 substitution was analyzed via restriction fragment length polymorphism (RFLP). Moreover, the promoter region of the RHCE gene was sequenced to search for other nucleotide substitutions between RHC and RHc. Agreement between prediction methods was evaluated using the Kappa statistic, and comparisons between methods were conducted via the χ2 test. RESULTS: The analysis revealed that the 48C allele, 109bp insertion, a specific pattern observed in RFLP results, and wild-type alleles of seven single nucleotide polymorphisms (SNPs) were in strong agreement with the Rh C, with Kappa coefficients exceeding 0.8. However, there were instances of false positives or false negatives (0.6% false negative rate for 109bp insertion and 5.4-8.2% false positive rates for other methods). The 109bp insertion method exhibited the highest accuracy in predicting the Rh C, at 99.4%, compared to other methods (P values≤0.001). Although no statistical differences were found among other methods for predicting Rh C (P values>0.05), the accuracies in descending order were 48C (94.6%) > rs586178 (92.7%) > rs4649082, rs2375313, rs2281179, rs2072933, rs2072932, and RFLP (92.4%) > rs2072931 (91.8%). CONCLUSIONS: None of the methods examined can independently and accurately predict the Rh C. However, the 109bp insertion test demonstrated the highest accuracy for predicting the Rh C in the Chinese Han population. Utilizing the 109bp insertion test in combination with other methods may enhance the accuracy of Rh C prediction.

Genotyping Hepatitis B virus by Next-Generation Sequencing: Detection of Mixed Infections and Analysis of Sequence Conservation.

Our aim was to develop an accurate, highly sensitive method for HBV genotype determination and detection of genotype mixtures. We examined the preS and 5' end of the HBV X gene (5X) regions of the HBV genome using next-generation sequencing (NGS). The 1852 haplotypes obtained were subjected to genotyping via the Distance-Based discrimination method (DB Rule) using two sets of 95 reference sequences of genotypes A-H. In clinical samples from 125 patients, the main genotypes were A, D, F and H in Caucasian, B and C in Asian and A and E in Sub-Saharan patients. Genotype mixtures were identified in 28 (22.40%) cases, and potential intergenotypic recombination was observed in 29 (23.20%) cases. Furthermore, we evaluated sequence conservation among haplotypes classified into genotypes A, C, D, and E by computing the information content. The preS haplotypes exhibited limited shared conserved regions, whereas the 5X haplotypes revealed two groups of conserved regions across the genotypes assessed. In conclusion, we developed an NGS-based HBV genotyping method utilizing the DB Rule for genotype classification. We identified two regions conserved across different genotypes at 5X, offering promising targets for RNA interference-based antiviral therapies.

Comparative evaluation of Anyplex II HPV28 and Allplex HPV28 molecular assays for human papillomavirus detection and genotyping in anogenital cancer screening.

Persistent infection with high-risk human papillomavirus (HPV) is recognized as the main cause for the development of anogenital cancers. This study prospectively evaluated the diagnostic performance of the novel Allplex-HPV28 assay with the Anyplex-II-HPV28 to detect and genotype HPV in 234 consecutive swabs and 32 biopsies of the anogenital tract from 265 patients with atypical findings in cytomorphological screening. Agreement in HPV-DNA detection between the Anyplex-II and Allplex-HPV28 assays was 99%. There was a notable diversity in the HPV-virome, with the most prevalent high-risk HPV types being 16, 53, 66, and 68. The agreement rates for detecting these genotypes exceeded 93% between the Anyplex-II and Allplex-HPV28 assays. Discrepancies in test results were solely noted for Anyplex-II-HPV28 results with a low signal intensity of "+", and for Allplex-HPV28 results with cycle thresholds of ≥36. The semi-quantitative analysis of HPV-DNA loads showed significant agreement between the Anyplex-II-HPV28 and Allplex-HPV28 assays (p < 0.001). Furthermore, HPV-DNA detection rates and mean HPV-DNA loads significantly correlated with the grade of abnormal changes identified in cytopathological assessment, being highest in cases of HSIL, condyloma accuminatum, and squamous cell carcinoma. Overall agreement rates for detecting specific HPV-types among the Anyplex-II and Allplex-HPV28 assays exceeded 99.5% in cases of atypical squamous cells, condyloma accuminatum, and squamous cell carcinoma. The novel Allplex-HPV28 assay shows good diagnostic performance in detecting and genotyping HPV commonly associated with anogenital cancers. Consequently, this assay could offer substantial potential for incorporation into future molecular screening programs for anogenital cancers in clinical settings.

Evaluation of an E6/E7 PCR-capillary electrophoresis fragment analysis in the genotyping of human papillomavirus in archival FFPE samples of oropharyngeal cancer.

Accumulating evidence has demonstrated that high-risk human papillomaviruses (HR-HPVs) are involved in the etiology of a subset of oropharyngeal squamous cell carcinoma (OPSCC). In this regard, the International Agency for Research on Cancer (IARC) has recommended direct molecular HPV testing. So far, there is no agreement on the most appropriate method for HPV detection on OPSCC formalin-fixed paraffin-embedded (FFPE) materials. In this study, we aimed to evaluate the performance of the high-sensitive SureX HPV assay in OPSCC FFPE tissues compared with LiPA-25 and p16ink4a immunostaining. A retrospective series of FFPE primary OPSCC cases were diagnosed between 2008 and 2019 and provided by the Henan Cancer Hospital, China. The level of agreement of two assays was determined using Cohen's Kappa (κ) statistics. A total of 230 FFPE OPSCC samples from tumor resections (n = 160) and diagnostic biopsies (n = 70) were detected. Sixty-six (28.7%) and 70 (30.4%) samples were identified as HPV-DNA-positive by LiPA-25 and SureX, respectively, of which HPV16 was largely the most common type (95.5% vs 94.3%). We found a perfect concordance between LiPA-25 and SureX for HPV-DNA status (κ = 0.906, 95% CI: 0.875-0.937) and for HPV16 (κ = 0.925, 95% CI: 0.897-0.953). In addition, SureX and p16ink4a immunostaining had a perfect concordance (κ = 0.917, 95% CI: 0.888-0.946). Moreover, the HPV-driven fraction, based on double positivity for HPV-DNA and p16ink4a, was similar between SureX (63 of 230, 27.4%) and LiPA-25 (60 of 230, 26.1%). Similar results were found in samples from resections and biopsies. SureX and LiPA-25 are comparable. SureX could be used for routine HPV-DNA detection and genotyping on archival OPSCC FFPE tissues.

Comparing the performances of SSR and SNP markers for population analysis in Theobroma cacao L., as alternative approach to validate a new ddRADseq protocol for cacao genotyping.

Proper cacao (Theobroma cacao L.) plant genotyping is mandatory for the conservation and use of the species genetic resources. A set of 15 international standard SSR markers was assumed as universal cacao genotyping system. Recently, different SNPs and SNP genotyping techniques have been exploited in cacao. However, a consensus on which to use has not been reached yet, driving the search for new approaches. To validate a new ddRADseq protocol for cacao genotyping, we compared the performances for population analysis of a dataset with 7,880 SNPs obtained from ddRADseq and the genotypic data from the aforementioned SSR set, using 158 cacao plants from productive farms and gene bank. Four genetic groups were identified with STRUCTURE and ADMIXTURE softwares using SSR and SNP data, respectively. Similarities of cacao ancestries among these groups allowed the identification of analogous pairs of groups of individuals, referred to as: G1SSR/G1SNP, G2SSR/G2SNP, G3SSR/G3SNP, G4SSR/G4SNP, whether SSRs or SNPs were used. Both marker systems identified Amelonado and Criollo as the most abundant cacao ancestries among all samples. Genetic distance matrices from both data types were significantly similar to each other according to Mantel test (p < 0.0001). PCoA and UPGMA clustering mostly confirmed the identified genetic groups. AMOVA and FST pairwise comparison revealed a moderate to very large genetic differentiation among identified groups from SSR and SNP data. Genetic diversity parameters from SSR (Hobs = 0.616, Hexp = 0.524 and PIC = 0.544) were higher than that from SNP data (0.288, 0.264, 0.230). In both cases, genetic groups carrying the highest Amelonado proportion (G1SSR and G1SNP) had the lowest genetic diversity parameters among the identified groups. The high congruence among population analysis results using both systems validated the ddRADseq protocol employed for cacao SNP genotyping. These results could provide new ways for developing a universal SNP-based genotyping system very much needed for cacao genetic studies.

Rapid and multi-target genotyping of Helicobacter pylori with digital microfluidics.

Helicobacter pylori (H. pylori) infection correlates closely with gastric diseases such as gastritis, ulcers, and cancer, influencing more than half of the world's population. Establishing a rapid, precise, and automated platform for H. pylori diagnosis is an urgent clinical need and would significantly benefit therapeutic intervention. Recombinase polymerase amplification (RPA)-CRISPR recently emerged as a promising molecular diagnostic assay due to its rapid detection capability, high specificity, and mild reaction conditions. In this work, we adapted the RPA-CRISPR assay on a digital microfluidics (DMF) system for automated H. pylori detection and genotyping. The system can achieve multi-target parallel detection of H. pylori nucleotide conservative genes (ureB) and virulence genes (cagA and vacA) across different samples within 30 min, exhibiting a detection limit of 10 copies/rxn and no false positives. We further conducted tests on 80 clinical saliva samples and compared the results with those derived from real-time quantitative polymerase chain reaction, demonstrating 100% diagnostic sensitivity and specificity for the RPA-CRISPR/DMF method. By automating the assay process on a single chip, the DMF system can significantly reduce the usage of reagents and samples, minimize the cross-contamination effect, and shorten the reaction time, with the additional benefit of losing the chance of experiment failure/inconsistency due to manual operations. The DMF system together with the RPA-CRISPR assay can be used for early detection and genotyping of H. pylori with high sensitivity and specificity, and has the potential to become a universal molecular diagnostic platform.

Effect of genotyping errors on linkage map construction based on repeated chip analysis of two recombinant inbred line populations in wheat (Triticum aestivum L.).

Linkage maps are essential for genetic mapping of phenotypic traits, gene map-based cloning, and marker-assisted selection in breeding applications. Construction of a high-quality saturated map requires high-quality genotypic data on a large number of molecular markers. Errors in genotyping cannot be completely avoided, no matter what platform is used. When genotyping error reaches a threshold level, it will seriously affect the accuracy of the constructed map and the reliability of consequent genetic studies. In this study, repeated genotyping of two recombinant inbred line (RIL) populations derived from crosses Yangxiaomai × Zhongyou 9507 and Jingshuang 16 × Bainong 64 was used to investigate the effect of genotyping errors on linkage map construction. Inconsistent data points between the two replications were regarded as genotyping errors, which were classified into three types. Genotyping errors were treated as missing values, and therefore the non-erroneous data set was generated. Firstly, linkage maps were constructed using the two replicates as well as the non-erroneous data set. Secondly, error correction methods implemented in software packages QTL IciMapping (EC) and Genotype-Corrector (GC) were applied to the two replicates. Linkage maps were therefore constructed based on the corrected genotypes and then compared with those from the non-erroneous data set. Simulation study was performed by considering different levels of genotyping errors to investigate the impact of errors and the accuracy of error correction methods. Results indicated that map length and marker order differed among the two replicates and the non-erroneous data sets in both RIL populations. For both actual and simulated populations, map length was expanded as the increase in error rate, and the correlation coefficient between linkage and physical maps became lower. Map quality can be improved by repeated genotyping and error correction algorithm. When it is impossible to genotype the whole mapping population repeatedly, 30% would be recommended in repeated genotyping. The EC method had a much lower false positive rate than did the GC method under different error rates. This study systematically expounded the impact of genotyping errors on linkage analysis, providing potential guidelines for improving the accuracy of linkage maps in the presence of genotyping errors.

Multiplex fluorescent amplification-refractory mutation system PCR method for the detection of 10 genetic defects in Holstein cattle and its comparison with the KASP genotyping assay.

The common deleterious genetic defects in Holstein cattle include haplotypes 1-6 (HH1-HH6), haplotypes for cholesterol deficiency (HCD), bovine leukocyte adhesion deficiency (BLAD), complex vertebral malformation (CVM) and brachyspina syndrome (BS). Recessive inheritance patterns of these genetic defects permit the carriers to function normally, but homozygous recessive genotypes cause embryo loss or neonatal death. Therefore, rapid detection of the carriers is essential to manage these genetic defects. This study was conducted to develop a single-tube multiplex fluorescent amplification-refractory mutation system (mf-ARMS) PCR method for efficient genotyping of these 10 genetic defects and to compare its efficiency with the kompetitive allele specific PCR (KASP) genotyping assay. The mf-ARMS PCR method introduced 10 sets of tri-primers optimized with additional mismatches in the 3' end of wild and mutant-specific primers, size differentiation between wild and mutant-specific primers, fluorescent labeling of universal primers, adjustment of annealing temperatures and optimization of primer concentrations. The genotyping of 484 Holstein cows resulted in 16.12% carriers with at least one genetic defect, while no homozygous recessive genotype was detected. This study found carrier frequencies ranging from 0.0% (HH6) to 3.72% (HH3) for individual defects. The mf-ARMS PCR method demonstrated improved detection, time and cost efficiency compared with the KASP method for these defects. Therefore, the application of mf-ARMS PCR for genotyping Holstein cattle is anticipated to decrease the frequency of lethal alleles and limit the transmission of these genetic defects.

A comprehensive benchmark of graph-based genetic variant genotyping algorithms on plant genomes for creating an accurate ensemble pipeline.

BACKGROUND: Although sequencing technologies have boosted the measurement of the genomic diversity of plant crops, it remains challenging to accurately genotype millions of genetic variants, especially structural variations, with only short reads. In recent years, many graph-based variation genotyping methods have been developed to address this issue and tested for human genomes. However, their performance in plant genomes remains largely elusive. Furthermore, pipelines integrating the advantages of current genotyping methods might be required, considering the different complexity of plant genomes. RESULTS: Here we comprehensively evaluate eight such genotypers in different scenarios in terms of variant type and size, sequencing parameters, genomic context, and complexity, as well as graph size, using both simulated and real data sets from representative plant genomes. Our evaluation reveals that there are still great challenges to applying existing methods to plants, such as excessive repeats and variants or high resource consumption. Therefore, we propose a pipeline called Ensemble Variant Genotyper (EVG) that can achieve better genotyping performance in almost all experimental scenarios and comparably higher genotyping recall and precision even using 5× reads. Furthermore, we demonstrate that EVG is more robust with an increasing number of graphed genomes, especially for insertions and deletions. CONCLUSIONS: Our study will provide new insights into the development and application of graph-based genotyping algorithms. We conclude that EVG provides an accurate, unbiased, and cost-effective way for genotyping both small and large variations and will be potentially used in population-scale genotyping for large, repetitive, and heterozygous plant genomes.