What Does 16S rRNA Gene-Targeted Next Generation Sequencing Contribute to the Study of Infective Endocarditis in Heart-Valve Tissue?

Infective endocarditis (IE) is a severe and life-threatening disease. Identification of infectious etiology is essential for establishing the appropriate antimicrobial treatment and decreasing mortality. The aim of this study was to explore the potential utility of metataxonomics for improving microbiological diagnosis of IE. Here, next-generation sequencing (NGS) of the V3–V4 region of the 16S rRNA gene was performed in 27 heart valve tissues (18 natives, 5 intravascular devices, and 4 prosthetics) from 27 patients diagnosed with IE (4 of them with negative blood cultures). Metataxonomics matched with conventional diagnostic techniques in 24/27 cases (88.9%). The same bacterial family was assigned to 24 cases; the same genus, to 23 cases; and the same species, to 13 cases. In 22 of them, the etiological agent was represented by percentages > 99% of the reads and in two cases, by ~70%. Staphylococcus aureus was detected in a previously microbiological undiagnosed patient. Thus, microbiological diagnosis with 16S rRNA gene targeted-NGS was possible in one more sample than using traditional techniques. The remaining two patients showed no coincidence between traditional and 16S rRNA gene-targeted NGS microbiological diagnoses. In addition, 16S rRNA gene-targeted NGS allowed us to suggest coinfections that were supported by clinical data in one patient, and minority records also verified mixed infections in three cases. In our series, metataxonomics was valid for the identification of the causative agents, although more studies are needed before implementation of 16S rRNA gene-targeted NGS for the diagnosis of IE.

Urine as a non-invasive alternative to blood for germline and somatic mutation detection in hepatocellular carcinoma

Cell-free DNA (cfDNA) from blood has become a promising analyte for cancer genetic liquid biopsy. Urinary cfDNA has been shown to contain mutations associated with non-genitourologic cancers including hepatocellular carcinoma (HCC). In this study, we evaluate urine as a noninvasive alternative to blood-based liquid biopsy in both germline and circulating tumor DNA (ctDNA) genotyping in HCC. Using quantitative PCR (qPCR), whole-genome sequencing (WGS), and targeted NGS, DNA isolated from blood or urine of patients with HCC was analyzed for overall genome coverage, HCC hotspot coverage, and germline or somatic mutation concordance. Targeted NGS of plasma and urine cfDNA was also performed for detection of somatic variants. We found urine cfDNA, similar to plasma cfDNA, showed a major mononucleosomal species of 150-180 bp in both healthy individuals and patients with HCC. By WGS, overall genome coverage breadth was similar between urine and plasma cfDNA, with higher fraction of covered cancer-associated mutation hotspots in urine cfDNA. qPCR analyses of HCC-associated mutations (TP53, CTNNB1, and TERT) in 101 patients with HCC revealed 78% overall concordance between plasma and urine. Targeted NGS of HCC-associated gene regions in additional 15 HCC patients showed a 97% overall position-level concordance between plasma and urine cfDNA. Collectively, urine DNA can potentially be used as a completely noninvasive liquid biopsy for HCC.Significance StatementHepatocellular carcinoma (HCC) is the most common liver cancer worldwide and the fastest growing gastrointestinal cancer in the U.S. Cell-free DNA (cfDNA) which originates from various cells undergoing apoptosis or necrosis including tumor cells, is present in all body fluids levels including urine. Urinary cfDNA isolated from patients with HCC showed a similar fragment size distribution, overall genome coverage, and comparable sensitivity for detecting HCC-associated variants compared to plasma cfDNA. Urine was also determined to be a reliable source of germline genotype information, similar to peripheral blood mononuclear cells in blood-based liquid biopsies. Urine cfDNA can be used as a completely non-invasive liquid biopsy in HCC.

Gonosomal Mosaicism for a Novel COL5A1 Pathogenic Variant in Classic Ehlers-Danlos Syndrome

(1) Background: Classic Ehlers-Danlos syndrome (cEDS) is a heritable connective tissue disorder characterized by joint hypermobility and skin hyperextensibility with atrophic scarring. Many cEDS individuals carry variants in either the COL5A1 or COL5A2 genes. Mosaicism is relatively common in heritable connective tissue disorders but is rare in EDS. In cEDS, a single example of presumed gonosomal mosaicism for a COL5A1 variant has been published to date. (2) Methods: An 8-year-old girl with cEDS was analyzed by next-generation sequencing (NGS). Segregation was performed by Sanger sequencing in her unaffected parents. In the father, the mosaicism of the variant was further analyzed by targeted NGS and droplet digital PCR (ddPCR) in the blood and by Sanger sequencing in other tissues. (3) Results: The NGS analysis revealed the novel germline heterozygous COL5A1 c.1369G>T, p.(Glu457*) variant in the proband. Sanger chromatogram of the father’s blood specimen suggested the presence of a low-level mosaicism for the COL5A1 variant, which was confirmed by NGS and estimated to be 4.8% by ddPCR. The mosaicism was also confirmed by Sanger sequencing in the father’s saliva, hair bulbs and nails. (4) Conclusions: We described the second case of cEDS caused by paternal gonosomal mosaicism in COL5A1. Parental mosaicism could be an issue in cEDS and, therefore, considered for appropriate genetic counseling.

Progressive Myoclonus Epilepsies

Background and ObjectivesTo assess the current diagnostic yield of genetic testing for the progressive myoclonus epilepsies (PMEs) of an Italian series described in 2014 where Unverricht-Lundborg and Lafora diseases accounted for ∼50% of the cohort.MethodsOf 47/165 unrelated patients with PME of indeterminate genetic origin, 38 underwent new molecular evaluations. Various next-generation sequencing (NGS) techniques were applied including gene panel analysis (n = 7) and/or whole-exome sequencing (WES) (WES singleton n = 29, WES trio n = 7, and WES sibling n = 4). In 1 family, homozygosity mapping was followed by targeted NGS. Clinically, the patients were grouped in 4 phenotypic categories: “Unverricht-Lundborg disease-like PME,” “late-onset PME,” “PME plus developmental delay,” and “PME plus dementia.”ResultsSixteen of 38 (42%) unrelated patients reached a positive diagnosis, increasing the overall proportion of solved families in the total series from 72% to 82%. Likely pathogenic variants were identified in NEU1 (2 families), CERS1 (1 family), and in 13 nonfamilial patients in KCNC1 (3), DHDDS (3), SACS, CACNA2D2, STUB1, AFG3L2, CLN6, NAXE, and CHD2. Across the different phenotypic categories, the diagnostic rate was similar, and the same gene could be found in different phenotypic categories.DiscussionThe application of NGS technology to unsolved patients with PME has revealed a collection of very rare genetic causes. Pathogenic variants were detected in both established PME genes and in genes not previously associated with PME, but with progressive ataxia or with developmental encephalopathies. With a diagnostic yield >80%, PME is one of the best genetically defined epilepsy syndromes.

Immune Repertoire Analysis of Multiple Myeloma Research Samples Using NGS Characterization of Multiple B Cell Receptors in a Single Reaction

Introduction B cell repertoire analysis by next-generation sequencing (NGS) is at the forefront of leukemia and lymphoma research. Some advantages provided by NGS-based techniques include a lower limit-of-detection and simpler paths to standardization compared to other methods. Importantly, in research of post-germinal B cell disorders, such as multiple myeloma (MM), NGS methods allow for the study of clonal lineage based on somatic hypermuation patterns. Current targeted NGS assays require multiple libraries to survey each B cell receptor chain (IGH, IgK, IgL), and this fact is highlighted when initial clonality detection fails due to mutations under primer binding sites. This issue can be especially true in MM which has a high rate of SHM. To address these issues, we have developed an assay for B cell analysis, based on Ion AmpliSeq™ technology, which enables efficient detection of IGH, IgK, and IgL chain rearrangements in a single reaction. Methods The B cell pan-clonality panel (Oncomine™ BCR Pan-Clonality Assay) targets the framework 3 (FR3) portion of the variable gene and the joining gene region of heavy- and light-chain loci (IGH, IgK, IgL) for all alleles found within the IMGT database, enabling readout of the complementary-determining region 3 (CDR3) sequence of each immunoglobulin chain. To maximize sensitivity, we included primers to amplify IgK loci rearrangements involving Kappa deletion element and the constant region intron. To evaluate assay performance, we conducted reproducibility studies and clonality assessment using gDNA from a total of 45 MM research samples. All MM cases examined in this work were confirmed clonal previously by light chain restriction via flow cytometry or IHC/ISH in tissue sections - 16 of the 45 MM samples were identified as lambda light chain restricted. For comparison, a small cohort of 12 B-ALL samples were also included in the study. Sequencing and repertoire analyses were performed using the Ion GeneStudio S5 System and Ion Reporter 5.16 analysis software. Results Clonality assessment of MM clinical research samples show an 93% overall positive detection rate by an assay which combines the IGH, IgK, and IgL chains in a single reaction using published guidelines for clonality assignment. Thirty-four of 45 samples show positive detection of an IGH rearrangement, while 41 of 45 showed positive detection of at least one light chain receptor. In total, 42 of 45 samples were deemed clonal by the single tube assay based on detection for one or more receptor. Clonality results for this sample set are well correlated with orthogonal data from flow, IHC/ISH, or alternate NGS assays. A clonal lambda light chain was identified in 14 of 16 samples determined to be lambda restricted by flow cytometry. In two of the lambda restricted samples only a clonal lambda rearrangement was identified, showing the benefit of including primers targeting both the kappa and lambda light chains in a pan-clonality NGS assay. Both the MM and B-ALL cohorts were evaluated for biased IGHV gene usage. IGHV3-11 was observed in 5 of 45 MM and 5 of 12 B-ALL samples. IGHV4-34, typically linked to autoreactive antibodies and underrepresented in germinal center and memory B-cells, was nonetheless found in 5 of 45 MM samples surveyed. Estimates of somatic hypermutation rates were calculated using the BCR pan-clonality assay. Most MM samples, as expected, contained some somatic hypermutation with 6 of 45 samples showing greater than 10% mutation rates. Automated lineage analysis, based on somatic hypermuation signatures within each sample, identified 8 of 45 MM samples which contained 5 or more clones in the primary clonal lineage, with one case containing a lineage with 23 clones. Two MM samples showed no somatic hypermutation as measured using the FR3 primers contained in the BCR pan-clonality assay. These samples were also evaluated using an FR1-J targeted NGS assay, which confirmed relatively low mutation rates for these MM samples at 0.44% and 1.3%, respectively. Conclusions These results demonstrate the utility of a novel assay for combined repertoire analysis of B cell receptor heavy and light chains in a single library preparation reaction. We expect this assay to simplify laboratory workflows and including analysis tools such as automated somatic hypermutation rate calculation and clonal lineage identification may open new paths for research in lymphoid cell disorders. For research use only. Disclosures Lowman: Thermo Fisher Scientific: Current Employment. Toro: Thermo Fisher Scientific: Current Employment. Pickle: Thermo Fisher Scientific: Current Employment. Ostresh: Thermo Fisher Scientific: Current Employment. Sarda: Thermo Fisher Scientific: Current Employment. Yang: Thermo Fisher Scientific: Current Employment.

Utilization of Non-Invasive Sample Sources for Identification of Somatic and Germline Mutations in Hematologic Malignancies and Clonal Hematopoiesis

Introduction A matched "tumor" and germline sample is required to unambiguously identify somatically acquired mutations in the blood or bone marrow of patients with hematologic malignancies or clonal hematopoiesis, particularly when variants of unknown significance (VUS) with a variant allele frequency (VAF) approximating 50% are encountered. Our goal was to identify sample sources for matched blood and germline samples to fit the following criteria: 1) non-invasive, 2) amenable to home collection by participants, and 3) stable at room temperature for an extended period. We hypothesized that saliva, comprised of mainly white blood cells as the DNA source, is a viable alternative to blood for identifying somatic hematopoietic mutations and that nail clippings provide adequate DNA devoid of contamination from blood cells to serve as a germline sample. To test this, a targeted NGS myeloid panel was performed on concurrently collected blood, saliva, and nail samples from patients with myeloproliferative neoplasms (MPN) or other clonal disorders. Methods Peripheral blood was collected in EDTA tubes, aliquoted into microcentrifuge tubes, and stored at -80°C until use. Saliva was collected using a DNA/RNA shield saliva collection kit (Zymo) and stored at -80°C until use. Fingernail or toenails were clipped into a plastic bag and stored at room temperature until use. For isolation of DNA from blood the DSP DNA Blood mini kit (QIAGEN) was used. For saliva and nails, the QIAmp DNA Investigator kit (QIAGEN) was used. After DNA quantification targeted NGS libraries were prepared from 100ng of DNA per sample using the ArcherDX VariantPlex Myeloid (SK0123) workflow. The resulting libraries were sequenced on an Illumina NextSeq500 instrument using v2 chemistry (Illumina, San Diego, CA), obtaining at least 4 millionreads per sample. The FASTQ data files were analyzed on ArcherDX Suite Analysis software (v.5.1.7) to identify SNPs, Indels, structural rearrangements, and Copy Number Variations. Results First, to test if nail clippings are a feasible source of germline DNA, we performed a targeted NGS myeloid panel on paired blood and nail from a patient with Polycythemia Vera (Patient #1). Clippings from approximately five nails was sufficient to yield 100ng of DNA. JAK2 V617F was detected at a low VAF in his nail sample (4% in nail vs 23% in blood), suggesting the presence of blood contamination. On subsequent samples, nail clippings were rinsed with water prior to DNA purification, and no MPN driver mutations were detected in washed nails (Patients #2-5). However, since processing of nails for DNA purification is time consuming and laborious, and the DNA yield from nails is quite limited, we are investigating alternative non-invasive sources for germline samples including nasal swabs. Sequencing of matched blood and saliva was performed from patients with all three MPN driver mutations, and in a patient with Clonal Cytopenia of Undetermined Significance (CCUS). All somatic mutations identified in the blood were also seen in the saliva, almost all had identical VAFs from both sample sources, even with VAFs as low as 3%. Conclusion Nail clippings are a feasible source for germline DNA in patients with hematologic malignancies and clonal hematopoiesis. Saliva is equivalent to peripheral blood for identifying somatic mutations in hematopoietic cells. These methods of sample collection are non-invasive, amenable to in home collection, and are temperature stable. Collection of saliva and nails could be easily utilized for remotely administered studies by mailing collection kits to participants, thus avoiding the cost and labor of a blood draw. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Variant Allele Frequency Status in Elderly Patients with Acute Myeloid Leukemia Can be Early Predictors of Responsiveness to Decitabine Treatment

As interest in elderly Acute Myeloid Leukemia (AML) patients increases, American society of hematology (ASH) 2020 guidelines for treating newly diagnosed AML in older adults suggested diverse treatment options. The guidelines suggest using monotherapy over combination of hypomethylation agent (HMAs) with other agents in newly diagnosed AML in older adults due to similar efficacy and the potential for more toxicity. HMAs alone is still used widely as an alternative treatment for patients who cannot use venetoclax due to the high cost and poor performance score. If there are early predictors of responsiveness to Decitabine mono therapy, it will be helpful to decide whether to combine Novel agents. This retrospective cohort study from a single institution aimed to evaluate the prognostic significance of Variant allele frequency (VAF) changes in elderly patients after 4 th cycle of decitabine. Total 123 patients with elderly AML were eligible. 57 patients performed follow-up bone marrow biopsy and 49 patients were available of follow up targeted NGS samples from biopsy after 4th cycle of decitabine. To clarify the immortal timed bias, landmark analyses were performed with patients (n=84) who remained at least the median time to perform follow-up bone marrow biopsy after 4th cycle of decitabine treatment. 24 patients (54.5%, 24 of 44) showed more than 50% decrease of VAF after 4 th cycle of decitabine (figure 1a). DMNT3A, TET2, IDH1, IDH2, and SETBP1 and SMC1A showed less than 50% of the decreases of VAF. Patients with DNA methylation genes showed significantly reduced VAF less than 50% (figure 1b). A significant difference of ∆VAF was observed depending on CR status (p=0.021). The survival outcome of patients who showed more than 50% decrease of initial VAF after 4th cycle of decitabine was significantly better than that that with less than 50% decrease of VAF(1-year OS VAF decrease ≥ 50% (n=23), 75.0%; VAF decrease < 50% (n=20), 38.5%; no mutation (n=12), 45.5%; not available of follow up targeted NGS sample (n=29), 16.6%; p < 0.001, figure 2a). Mutations in DNMT3A, TET2, and ASXL1 (DTA genes) were detected in samples from 19 patients at diagnosis. After the exclusion of DTA mutations, the survival outcome improved prognostic risk stratification power of NGS-based MRD assessment in AML. The survival outcome of patients who showed more than 50% decrease of initial VAF after 4th cycle of decitabine was significantly better than that that with less than 50% decrease of VAF(1-year OS VAF decrease ≥ 50% (n=24), 75.0%; VAF decrease < 50% (n=19), 35.1%; no mutation (n=12), 50.1%; not available of follow up targeted NGS sample (n=29), 16.6%; p<0.001, figure 2b). In conclusion, more than 50% decrease of VAF was important negative prognostic factors by improving overall response rate and OS. In case of patients with older adults who received decitabine treatment, if follow up BM biopsy after 4 th cycles of decitabine treatment showed more than 50% reduction of VAF, it may suggest to maintain decitabine treatment. However, if VAF is reduced by less than 50% in follow up BM biopsy, the residual disease burden is considered for the selection of combination treatment to improve survival outcome. Figure 1 Figure 1. Disclosures Kim: Bristol-Meier Squibb: Research Funding; Paladin: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.

A Comprehensive, Targeted NGS Approach to Assessing Molecular Diagnosis of Lysosomal Storage Diseases

With over 60 different disorders and a combined incidence occurring in 1:5000–7000 live births, lysosomal storage diseases (LSDs) represent a major public health problem and constitute an enormous burden for affected individuals and their families. Several reasons make the diagnosis of LSDs an arduous task for clinicians, including the phenotype and penetrance variability, the shared signs and symptoms, and the uncertainties related to biochemical enzymatic assay results. Developing a powerful diagnostic tool based on next generation sequencing (NGS) technology may help reduce the delayed diagnostic process for these families, leading to better outcomes for current therapies and providing the basis for more appropriate genetic counseling. Herein, we employed a targeted NGS-based panel to scan the coding regions of 65 LSD-causative genes. A reference group sample (n = 26) with previously known genetic mutations was used to test and validate the entire workflow. Our approach demonstrated elevated analytical accuracy, sensitivity, and specificity. We believe the adoption of comprehensive targeted sequencing strategies into a routine diagnostic route may accelerate both the identification and management of LSDs with overlapping clinical profiles, producing a significant reduction in delayed diagnostic response with beneficial results in the treatment outcome.

Application of a custom NGS Gene Panel revealed a high diagnostic utility for molecular testing of hereditary ataxias.

Background Hereditary ataxias (HA) are a rare group of heterogeneous disorders. Here, we present results of molecular testing a group of ataxia patients using custom-designed Next Generation Sequencing (NGS) panel. Due to genetic and clinical overlapping of hereditary ataxias and spastic paraplegias (HSP), designed panel encompassing together HA and HSP genes. Methods The NGS libraries comprising coding sequence for 152 genes were performed using KAPA HyperPlus and HyperCap Target Enrichment Kit and sequenced on the MiSeq instrument. Obtained results were analyzed using BaseSpace Variant Interpreter and Integrative Genomics Viewer. All pathogenic and likely pathogenic variants were confirmed using the Sanger sequencing. Results A total of 29 patients with hereditary ataxias were enrolled to the NGS testing, and 16 patients had a confirmed molecular diagnosis with diagnostic efficiency of 55.2%. Pathogenic or likely pathogenic mutations were identified in 10 different genes: POLG (PEOA1, n=3; SCAE, n=2), CACNA1A (EA2, n=2), SACS (ARSACS, n=2), SLC33A1 (SPG42, n=2), STUB1 (SCA48, n=1), SPTBN2 (SCA5, n=1), TGM6 (SCA35, n=1), SETX (AOA2, n=1), ANO10 (SCAR10, n=1), SPAST (SPG4, n=1). Conclusions We demonstrated that approach based on targeted NGS panel can be highly effective and useful tool in the molecular diagnosis of ataxia patients. Furthermore, we highlight that sequencing panel targeted to ataxias together with HSP genes increase the diagnostic success.