Cryptic TCF3 fusions in childhood leukemia: Detection by RNA sequencing.

Acute lymphoblastic leukemia (ALL) is the most frequent malignancy in childhood and adolescence. In more than 60% of cases of this heterogeneous disease, a genetic marker is identified via cytogenetic or molecular analyses. TCF3 gene fusions occur in 5%-11% of ALL patients. In < 1%, the TCF3 alteration in ALL leads to a TCF3-HLF fusion gene. Even though this is a very rare event, the detection of a TCF3-HLF fusion gene is associated with a very poor prognosis with incurable relapses in almost all patients. The frequent TCF3-PBX1 fusion gene, which is detectable in 5%-10% of childhood B-cell precursor ALLs and ~3.8% of adult B-cell precursor ALLs, is associated with a rather good prognosis, that is, an observed event-free 5-year survival of approximately 85%. Thus, the distinction of the different partner genes fused to TCF3 is essential for risk assessment. To verify RNA sequencing as a tool for detection of known and unknown fusion genes, we screened 200 cases of pediatric B-cell precursor ALL with "targeted" RNA sequencing in a pilot project in comparison to classical cytogenetic analyses (chromosome R-banding analysis), fluorescence in situ hybridization, and PCR. We observed a TCF3 fusion gene in 6.5% (13/200) of the patients. Ten (5%) patients displayed a TCF3-PBX1 fusion gene, two (1%) patients a TCF3-FLI1 fusion gene, and one (0.5%) patient a TCF3-HLF fusion gene. For the TCF3 fusions, we obtained discrepant results with the different methods, which are described in the article. Taken together, translocations leading to TCF3 fusion genes might appear cryptic and may remain undetected by a single method.

Copy Number Analysis in a Large Cohort Suggestive of Inborn Errors of Immunity Indicates a Wide Spectrum of Relevant Chromosomal Losses and Gains.

Inborn errors of immunity (IEI) are genetically driven disorders. With the advancement of sequencing technologies, a rapidly increasing number of gene defects has been identified, thereby mirroring the high heterogeneity in immunological and clinical presentations observed in patients. However, for a large majority of patients, no causative single nucleotide variant (SNV) or small indel can be identified using next-generation sequencing. First studies have shown that also copy number variants (CNVs) can cause IEI. Unfortunately, CNVs are not well examined in many routine diagnostic settings and the aim of this study was to assess the number of clinically relevant chromosomal losses and gains in a large cohort. We identified a total of 20 CNVs using whole exome sequencing data of a cohort of 191 patients with a suspected IEI. A definite molecular diagnosis could be made in five patients (2.6%), including pathogenic deletions affecting ICOS, TNFAIP3, and 22q11.2. CNVs of uncertain significance were observed in fifteen patients (7.9%), including deletions of 11q22.1q22.3 and 16p11.2 but also duplications affecting entire or parts of genes previously associated with IEI. Importantly, five patients carrying a CNV of uncertain significance also carried pathogenic or likely pathogenic SNVs (PIK3R1, NFKB1, NLRC4, DOCK2), or SNVs of unknown significance (NFKB2). This cooccurrence of SNVs and CNVs suggests modifying effects in some patients, and functional follow-up is warranted now in order to better understand phenotypic heterogeneity. In summary, the diagnostic yield of IEI can be increased substantially by evaluating CNVs, which allows an improved therapeutic management in those patients.

Genome-wide association study of asthma exacerbations despite inhaled corticosteroid use.

RATIONALE: Substantial variability in response to asthma treatment with inhaled corticosteroids (ICS) has been described among individuals and populations, suggesting the contribution of genetic factors. Nonetheless, only a few genes have been identified to date. We aimed to identify genetic variants associated with asthma exacerbations despite ICS use in European children and young adults and to validate the findings in non-Europeans. Moreover, we explored whether a gene-set enrichment analysis could suggest potential novel asthma therapies. METHODS: A genome-wide association study (GWAS) of asthma exacerbations was tested in 2681 children of European descent treated with ICS from eight studies. Suggestive association signals were followed up for replication in 538 European asthma patients. Further evaluation was performed in 1773 non-Europeans. Variants revealed by published GWAS were assessed for replication. Additionally, gene-set enrichment analysis focused on drugs was performed. RESULTS: 10 independent variants were associated with asthma exacerbations despite ICS treatment in the discovery phase (p≤5×10-6). Of those, one variant at the CACNA2D3-WNT5A locus was nominally replicated in Europeans (rs67026078; p=0.010), but this was not validated in non-European populations. Five other genes associated with ICS response in previous studies were replicated. Additionally, an enrichment of associations in genes regulated by trichostatin A treatment was found. CONCLUSIONS: The intergenic region of CACNA2D3 and WNT5A was revealed as a novel locus for asthma exacerbations despite ICS treatment in European populations. Genes associated were related to trichostatin A, suggesting that this drug could regulate the molecular mechanisms involved in treatment response.

ADRB2 haplotypes and asthma exacerbations in children and young adults: An individual participant data meta-analysis.

BACKGROUND: The polymorphism Arg16 in ß2 -adrenergic receptor (ADRB2) gene has been associated with an increased risk of exacerbations in asthmatic children treated with long-acting ß2 -agonists (LABA). However, it remains unclear whether this increased risk is mainly attributed to this single variant or the combined effect of the haplotypes of polymorphisms at codons 16 and 27. OBJECTIVE: We assessed whether the haplotype analysis could explain the association between the polymorphisms at codons 16 (Arg16Gly) and 27 (Gln27Glu) in ADRB2 and risk of asthma exacerbations in patients treated with inhaled corticosteroids (ICS) plus LABA. METHODS: The study was undertaken using data from 10 independent studies (n = 5903) participating in the multi-ethnic Pharmacogenomics in Childhood Asthma (PiCA) consortium. Asthma exacerbations were defined as asthma-related use of oral corticosteroids or hospitalizations/emergency department visits in the past 6 or 12 months prior to the study visit/enrolment. The association between the haplotypes and the risk of asthma exacerbations was performed per study using haplo.stats package adjusted for age and sex. Results were meta-analysed using the inverse variance weighting method assuming random-effects. RESULTS: In subjects treated with ICS and LABA (n = 832, age: 3-21 years), Arg16/Gln27 versus Gly16/Glu27 (OR: 1.40, 95% CI: 1.05-1.87, I2  = 0.0%) and Arg16/Gln27 versus Gly16/Gln27 (OR: 1.43, 95% CI: 1.05-1.94, I2  = 0.0%), but not Gly16/Gln27 versus Gly16/Glu27 (OR: 0.99, 95% CI: 0.71-1.39, I2  = 0.0%), were significantly associated with an increased risk of asthma exacerbations. The sensitivity analyses indicated no significant association between the ADRB2 haplotypes and asthma exacerbations in the other treatment categories, namely as-required short-acting ß2 -agonists (n = 973), ICS monotherapy (n = 2623), ICS plus leukotriene receptor antagonists (LTRA; n = 338), or ICS plus LABA plus LTRA (n = 686). CONCLUSION AND CLINICAL RELEVANCE: The ADRB2 Arg16 haplotype, presumably mainly driven by the Arg16, increased the risk of asthma exacerbations in patients treated with ICS plus LABA. This finding could be beneficial in ADRB2 genotype-guided treatment which might improve clinical outcomes in asthmatic patients.

Frequency and prognostic impact of PAX5 p.P80R in pediatric acute lymphoblastic leukemia patients treated on an AIEOP-BFM acute lymphoblastic leukemia protocol.

PAX5 is a member of the paired box (PAX) family of transcription factors involved in B-cell development. PAX5P80R has recently been described as a distinct genetic B-cell precursor (BCP) acute lymphoblastic leukemia (ALL) subtype with a favorable prognosis in adults. In contrast, an unfavorable outcome has been observed in children. Our aim was to determine the frequency of PAX5P80R in childhood BCP-ALL treated according to the Associazione Italiana Ematologia ed Oncologia Pediatrica-Berlin-Frankfurt-Muenster (AIEOP-BFM) ALL 2000 protocol and to evaluate its clinical significance within this study cohort. The analyses included 1237 patients with ALL treated in the AIEOP-BFM ALL 2000 trial with complete information for copy number variations (CNVs) of IKZF1, PAX5, ETV6, RB1, BTG1, EBF1, CDKN2A, CDKN2B, and ERG. A customized TaqMan genotyping assay was used to screen for PAX5P80R . Sanger sequencing was used to confirm PAX5P80R -positive results as well as to screen for second variants in PAX5. Agilent CGH + SNP arrays (e-Array design 85 320; Agilent Technologies) were performed in PAX5P80R -positive patients to verify additional CNVs. Almost 2% (20/1028) of our BCP-ALL cohort were PAX5P80R -positive. White blood cell counts higher than 50 000/µl as well as male sex were significantly (P < .05) associated with PAX5P80R . Most of the PAX5P80R -positive cases were 10 years of age or older. PAX5P80R -positive samples were enriched for deletions affecting PAX5, IKZF1, CDKN2A, and CDKN2B. Compared to PAX5P80R -wildtype BCP-ALL, PAX5P80R -positive patients showed a significantly reduced 5-year overall survival (P = .042). Further studies should evaluate the interaction of PAX5P80R with other genetic aberrations to further stratify intermediate risk pediatric BCP-ALL.

Implementation of RNA sequencing and array CGH in the diagnostic workflow of the AIEOP-BFM ALL 2017 trial on acute lymphoblastic leukemia.

Risk-adapted therapy has significantly contributed to improved survival rates in pediatric acute lymphoblastic leukemia (ALL) and reliable detection of chromosomal aberrations is mandatory for risk group stratification. This study evaluated the applicability of panel-based RNA sequencing and array CGH within the diagnostic workflow of the German study group of the international AIEOP-BFM ALL 2017 trial. In a consecutive cohort of 117 children with B cell precursor (BCP) ALL, array analysis identified twelve cases with an IKZF1plus profile of gene deletions and one case of masked hypodiploidy. Genetic markers BCR-ABL1 (n = 1), ETV6-RUNX1 (n = 25), and rearrangements involving KMT2A (n = 3) or TCF3 (n = 3) were assessed by established conventional techniques such as karyotyping, FISH, and RT-PCR. Comparison of these results with RNA sequencing analysis revealed overall consistency in n=115/117 cases, albeit with one undetected AFF1-KMT2A fusion in RNA sequencing and one undetected ETV6-RUNX1 fusion in conventional analyses. The combined application of RNA sequencing, FISH, and CGH+SNP array reliably detected all genetic markers necessary for risk stratification and will be used as the diagnostic standard workflow for BCP-ALL patients enrolled in the AIEOP-BFM ALL 2017 study. Prospectively, consistent collection of genome-wide CGH+SNP array as well as RNA sequencing data will be a valuable source to elucidate new prognostic lesions beyond established markers of pediatric ALL. In this respect, RNA sequencing identified various gene fusions in up to half of the IKZF1plus (n = 6/12) and B-other (n = 19/36) cases but not in cases with hyperdiploid karyotypes (n = 35). Among these fusions, this study reports several previously undescribed in frame PAX5 fusions, including PAX5-MYO1G and PAX5-NCOA6.

Genome-wide association study of inhaled corticosteroid response in admixed children with asthma.

BACKGROUND: Inhaled corticosteroids (ICS) are the most widely prescribed and effective medication to control asthma symptoms and exacerbations. However, many children still have asthma exacerbations despite treatment, particularly in admixed populations, such as Puerto Ricans and African Americans. A few genome-wide association studies (GWAS) have been performed in European and Asian populations, and they have demonstrated the importance of the genetic component in ICS response. OBJECTIVE: We aimed to identify genetic variants associated with asthma exacerbations in admixed children treated with ICS and to validate previous GWAS findings. METHODS: A meta-analysis of two GWAS of asthma exacerbations was performed in 1347 admixed children treated with ICS (Hispanics/Latinos and African Americans), analysing 8.7 million genetic variants. Those with P ≤ 5 × 10-6 were followed up for replication in 1697 asthmatic patients from six European studies. Associations of ICS response described in published GWAS were followed up for replication in the admixed populations. RESULTS: A total of 15 independent variants were suggestively associated with asthma exacerbations in admixed populations (P ≤ 5 × 10-6 ). One of them, located in the intergenic region of APOBEC3B and APOBEC3C, showed evidence of replication in Europeans (rs5995653, P = 7.52 × 10-3 ) and was also associated with change in lung function after treatment with ICS (P = 4.91 × 10-3 ). Additionally, the reported association of the L3MBTL4-ARHGAP28 genomic region was confirmed in admixed populations, although a different variant was identified. CONCLUSIONS AND CLINICAL RELEVANCE: This study revealed the novel association of APOBEC3B and APOBEC3C with asthma exacerbations in children treated with ICS and replicated previously identified genomic regions. This contributes to the current knowledge about the multiple genetic markers determining responsiveness to ICS which could lead in the future the clinical identification of those asthma patients who are not able to respond to such treatment.

Breast cancer patients suggestive of Li-Fraumeni syndrome: mutational spectrum, candidate genes, and unexplained heredity.

BACKGROUND: Breast cancer is the most prevalent tumor entity in Li-Fraumeni syndrome. Up to 80% of individuals with a Li-Fraumeni-like phenotype do not harbor detectable causative germline TP53 variants. Yet, no systematic panel analyses for a wide range of cancer predisposition genes have been conducted on cohorts of women with breast cancer fulfilling Li-Fraumeni(-like) clinical diagnostic criteria. METHODS: To specifically help explain the diagnostic gap of TP53 wild-type Li-Fraumeni(-like) breast cancer cases, we performed array-based CGH (comparative genomic hybridization) and panel-based sequencing of 94 cancer predisposition genes on 83 breast cancer patients suggestive of Li-Fraumeni syndrome who had previously had negative test results for causative BRCA1, BRCA2, and TP53 germline variants. RESULTS: We identified 13 pathogenic or likely pathogenic germline variants in ten patients and in nine genes, including four copy number aberrations and nine single-nucleotide variants or small indels. Three patients presented as double-mutation carriers involving two different genes each. In five patients (5 of 83; 6% of cohort), we detected causative pathogenic variants in established hereditary breast cancer susceptibility genes (i.e., PALB2, CHEK2, ATM). Five further patients (5 of 83; 6% of cohort) were found to harbor pathogenic variants in genes lacking a firm association with breast cancer susceptibility to date (i.e., Fanconi pathway genes, RECQ family genes, CDKN2A/p14ARF, and RUNX1). CONCLUSIONS: Our study details the mutational spectrum in breast cancer patients suggestive of Li-Fraumeni syndrome and indicates the need for intensified research on monoallelic variants in Fanconi pathway and RECQ family genes. Notably, this study further reveals a large portion of still unexplained Li-Fraumeni(-like) cases, warranting comprehensive investigation of recently described candidate genes as well as noncoding regions of the TP53 gene in patients with Li-Fraumeni(-like) syndrome lacking TP53 variants in coding regions.

6q12 and 11p14 variants are associated with postnatal exhaled nitric oxide levels and respiratory symptoms.

BACKGROUND: Exhaled nitric oxide (eNO) is a biomarker of airway inflammation and seems to precede respiratory symptoms, such as asthma, in childhood. Identifying genetic determinants of postnatal eNO levels might aid in unraveling the role of eNO in epithelial function or airway inflammation and disease. OBJECTIVE: We sought to identify genetic determinants of early postnatal eNO levels and subsequent respiratory symptoms during the first year of life. METHODS: Within a population-based birth cohort, eNO levels were measured in healthy term infants aged 5 weeks during quiet tidal breathing in unsedated sleep. We assessed associations of single nucleotide polymorphisms with eNO levels in a genome-wide association study and subsequent symptoms of lower respiratory tract infections during the first year of life and asked whether this was modified by prenatal and early-life environmental factors. RESULTS: We identified thus far unknown determinants of infant eNO levels: rs208515 (P = 3.3 × 10-8), which is located at 6q12, probably acting in "trans" and explaining 10.3% of eNO level variance, and rs1441519 (P = 1.6 × 10-6), which is located at 11p14, potentially affecting nitric oxide synthase 3 (NOS3) expression, as shown by means of in vitro functional analyses. Moreover, the 6q12 locus was inversely associated with subsequent respiratory symptoms (P < .05) and time to recovery after first respiratory symptoms during the first year of life (P < .05). CONCLUSION: The identification of novel genetic determinants of infant eNO levels might implicate that postnatal eNO metabolism in healthy infants before first viral infections and sensitization is related to mechanisms other than those associated with asthma, atopy, or increased risk thereof later in life.

Doublesex and mab-3 related transcription factor 1 (DMRT1) is a sex-specific genetic determinant of childhood-onset asthma and is expressed in testis and macrophages.

BACKGROUND: Asthma is a disease affecting more boys than girls in childhood and more women than men in adulthood. The mechanisms behind these sex-specific differences are not yet understood. OBJECTIVE: We analyzed whether and how genetic factors contribute to sex-specific predisposition to childhood-onset asthma. METHODS: Interactions between sex and polymorphisms on childhood asthma risk were evaluated in the Multicentre Asthma Genetics in Childhood Study (MAGICS)/Phase II International Study of Asthma and Allergies in Childhood (ISAAC II) population on a genome-wide level, and findings were validated in independent populations. Genetic fine mapping of sex-specific asthma association signals was performed, and putatively causal polymorphisms were characterized in vitro by using electrophoretic mobility shift and luciferase activity assays. Gene and protein expression of the identified gene doublesex and mab-3 related transcription factor 1 (DMRT1) were measured in different human tissues by using quantitative real-time PCR and immunohistochemistry. RESULTS: Polymorphisms in the testis-associated gene DMRT1 displayed interactions with sex on asthma status in a population of primarily clinically defined asthmatic children and nonasthmatic control subjects (lowest P = 5.21 × 10(-6)). Replication of this interaction was successful in 2 childhood populations clinically assessed for asthma but showed heterogeneous results in other population-based samples. Polymorphism rs3812523 located in the putative DMRT1 promoter was associated with allele-specific changes in transcription factor binding and promoter activity in vitro. DMRT1 expression was observed not only in the testis but also in lung macrophages. CONCLUSION: DMRT1 might influence sex-specific patterns of childhood asthma, and its expression in testis tissue and lung macrophages suggests a potential involvement in hormone or immune cell regulation.

IL-33 polymorphisms are associated with increased risk of hay fever and reduced regulatory T cells in a birth cohort.

BACKGROUND: IL-33 polymorphisms influence the susceptibility to asthma. IL-33 indirectly induces Th2-immune responses via dendritic cell activation, being important for development of atopic diseases. Furthermore, IL-33 upregulates regulatory T cells (Tregs), which are critical for healthy immune homeostasis. This study investigates associations between IL-33 polymorphisms during the development of childhood atopic diseases and underlying mechanisms including immune regulation of Tregs. METHODS: Genotyping of IL-33-polymorphisms (rs928413, rs1342326) was performed by MALDI-TOF-MS in 880 of 1133 PASTURE/EFRAIM children. In 4.5-year-old German PASTURE/EFRAIM children (n = 99), CD4+ CD25high FOXP3+ Tregs were assessed by flow cytometry following 24-h incubation of PBMCs with PMA/ionomycin, LPS or without stimuli (U). SOCS3, IL1RL1, TLR4 mRNA expression and sST2 protein levels ex vivo were measured in PASTURE/EFRAIM children by real-time PCR or ELISA, respectively. Health outcomes (hay fever, asthma) were assessed by questionnaires at the age of 6 years. RESULTS: rs928413 and rs1342326 were positively associated with hay fever (OR = 1.77, 95%CI = 1.02-3.08; OR = 1.79, 95%CI = 1.04-3.11) and CD4+ CD25high FOXP3+ Tregs (%) decreased in minor allele homozygotes/heterozygotes compared to major allele homozygotes (p(U) = 0.004; p(LPS) = 0.005; p(U) = 0.001; p(LPS) = 0.012). SOCS3 mRNA expression increased in minor allele homozygotes and heterozygotes compared with major allele homozygotes for both IL-33-polymorphisms (p(rs928413) = 0.032, p(rs1342326) = 0.019) and negatively correlated to Tregs. CONCLUSIONS: IL-33-polymorphisms rs928413 and rs1342326 may account for an increased risk of hay fever with the age of 6 years. Lower Tregs and increased SOCS3 in combined heterozygotes and minor allele homozygotes may be relevant for hay fever development, pointing towards dysbalanced immune regulation and insufficient control of allergic inflammation.

Polymorphisms related to ORMDL3 are associated with asthma susceptibility, alterations in transcriptional regulation of ORMDL3, and changes in TH2 cytokine levels.

BACKGROUND: Chromosome 17q21, harboring the orosomucoid 1-like 3 (ORMDL3) gene, has been consistently associated with childhood asthma in genome-wide association studies. OBJECTIVE: We investigated genetic variants in and around ORMDL3 that can change the function of ORMDL3 and thus contribute to asthma susceptibility. METHODS: We performed haplotype analyses and fine mapping of the ORMDL3 locus in a cross-sectional (International Study of Asthma and Allergies in Childhood Phase II, n = 3557 total subjects, n = 281 asthmatic patients) and case-control (Multicenter Asthma Genetics in Childhood Study/International Study of Asthma and Allergies in Childhood Phase II, n = 1446 total subjects, n = 763 asthmatic patients) data set to identify putative causal single nucleotide polymorphisms (SNPs) in the locus. Top asthma-associated polymorphisms were analyzed for allele-specific effects on transcription factor binding and promoter activity in vitro and gene expression in PBMCs after stimulation ex vivo. RESULTS: Two haplotypes (H1 and H2) were significantly associated with asthma in the cross-sectional (P = 9.9 × 10(-5) and P = .0035, respectively) and case-control (P = 3.15 × 10(-8) and P = .0021, respectively) populations. Polymorphisms rs8076131 and rs4065275 were identified to drive these effects. For rs4065275, a quantitative difference in transcription factor binding was found, whereas for rs8076131, changes in upstream stimulatory factor 1 and 2 transcription factor binding were observed in vitro by using different cell lines and PBMCs. This might contribute to detected alterations in luciferase activity paralleled with changes in ORMDL3 gene expression and IL-4 and IL-13 cytokine levels ex vivo in response to innate and adaptive stimuli in an allele-specific manner. Both SNPs were in strong linkage disequilibrium with asthma-associated 17q21 SNPs previously related to altered ORMDL3 gene expression. CONCLUSION: Polymorphisms in a putative promoter region of ORMDL3, which are associated with childhood asthma, alter transcriptional regulation of ORMDL3, correlate with changes in TH2 cytokines levels, and therefore might contribute to the childhood asthma susceptibility signal from 17q21.

Regulation of TH17 markers early in life through maternal farm exposure.

BACKGROUND: Previous studies suggested that maternal farm exposure during pregnancy modulates early immune development toward an allergy-protective status potentially mediated by TH1 or regulatory T (Treg) cells. However, the underlying mechanisms might involve immune modulation of additional T-cell populations, such as TH17 cells, influenced by genetic predisposition. OBJECTIVE: We examined the role of maternal farm exposure and genetic predisposition on TH17 cell responses to innate and adaptive immune stimulation in cord blood. METHODS: Eighty-four pregnant mothers were recruited before delivery. Detailed questionnaires (60 nonfarming mother, 22 farming mothers, and 2 exclusions) assessed farming exposures. Cord blood was stimulated with lipid A, peptidoglycan (Ppg), or PHA. TH17 lineage (retinoic acid receptor-related orphan receptor C [RORC], retinoic acid receptor-related orphan receptor α [RORA], IL-23 receptor [IL23R], IL17, IL17F, and IL22) and Treg cell markers (forkhead box protein 3 [FOXP3], lymphocyte activation gene 3 [LAG3], and glucocorticoid-induced TNF receptor [GITR]) were assessed at the mRNA level. TH17/Treg/TH1/TH2 cytokines and 7 single nucleotide polymorphisms within the TH17 lineage (RORC, IL23R, and IL17) were examined. RESULTS: TH17 lineage mRNA markers were expressed at birth at low concentrations independent of maternal farm exposure. A positive correlation between TH17 lineage markers and FOXP3 (mRNA) was observed on stimulation (nonfarming mothers: lipid A, Ppg, and PHA; farming mothers: Ppg and PHA), influenced by maternal farming. Specific single nucleotide polymorphisms within the TH17 lineage genes influenced gene expression of TH17 and Treg cell markers and cytokine secretion. CONCLUSIONS: Gene expression of TH17 lineage markers in cord blood was not influenced by maternal farming. Yet TH17 and Treg cell markers were positively correlated and influenced by maternal farm exposure. Our data suggest that prenatal exposures and genetic predisposition play a role during early TH17 immune maturation, potentially regulating the development of immune-mediated diseases, such as childhood asthma.

Comprehensive sequential genetic analysis delineating frequency, patterns, and prognostic impact of genomic dynamics in a real-world cohort of patients with lower-risk MDS.

The acquisition of subsequent genetic lesions (clonal evolution, CE) and/or the expansion of existing clones (CEXP) contributes to clonal dynamics (CD) in myelodysplastic syndromes (MDS). Although CD plays an important role in high-risk patients in disease progression and transformation into acute myeloid leukemia (AML), knowledge about CD in lower-risk MDS (LR-MDS) patients is limited due to lack of robust longitudinal data considering the long clinically stable courses of the disease. In this retrospective analysis, we delineate the frequency and the prognostic impact of CD in an unselected real-world cohort of LR-MDS patients. We screened 68 patients with a median follow-up of 40.5 months and a median of 7.5 (range: 2-22) timepoints for CE and CEXP detected by chromosomal banding analysis, fluorescence in situ hybridization, sequencing, and molecular karyotyping. In 30/68 patients, 47 CE events and a CD rate of 1 event per 4 years were documented. Of note, patients with at least 1 CE event had an increased probability for subsequent treatment. Unexpectedly, CE did not correlate with inferior outcomes, which could be reasonably explained by CD detection triggering the subsequent start of a disease-modifying therapy.

Genetic Predisposition to Neurological Complications in Patients with COVID-19.

Several studies have identified rare and common genetic variants associated with severe COVID-19, but no study has reported genetic determinants as predisposition factors for neurological complications. In this report, we identified rare/unique structural variants (SVs) implicated in neurological functions in two individuals with neurological manifestations of COVID-19. This report highlights the possible genetic link to the neurological symptoms with COVID-19 and calls for a collective effort to study these cohorts for a possible genetic linkage.

Optical genome mapping identifies rare structural variations as predisposition factors associated with severe COVID-19.

Impressive global efforts have identified both rare and common gene variants associated with severe COVID-19 using sequencing technologies. However, these studies lack the sensitivity to accurately detect several classes of variants, especially large structural variants (SVs), which account for a substantial proportion of genetic diversity including clinically relevant variation. We performed optical genome mapping on 52 severely ill COVID-19 patients to identify rare/unique SVs as decisive predisposition factors associated with COVID-19. We identified 7 SVs involving genes implicated in two key host-viral interaction pathways: innate immunity and inflammatory response, and viral replication and spread in nine patients, of which SVs in STK26 and DPP4 genes are the most intriguing candidates. This study is the first to systematically assess the potential role of SVs in the pathogenesis of COVID-19 severity and highlights the need to evaluate SVs along with sequencing variants to comprehensively associate genomic information with interindividual variability in COVID-19 phenotypes.

The Clinical Utility of Optical Genome Mapping for the Assessment of Genomic Aberrations in Acute Lymphoblastic Leukemia.

Acute lymphoblastic leukemia (ALL) is the most prevalent type of cancer occurring in children. ALL is characterized by structural and numeric genomic aberrations that strongly correlate with prognosis and clinical outcome. Usually, a combination of cyto- and molecular genetic methods (karyotyping, array-CGH, FISH, RT-PCR, RNA-Seq) is needed to identify all aberrations relevant for risk stratification. We investigated the feasibility of optical genome mapping (OGM), a DNA-based method, to detect these aberrations in an all-in-one approach. As proof of principle, twelve pediatric ALL samples were analyzed by OGM, and results were validated by comparing OGM data to results obtained from routine diagnostics. All genomic aberrations including translocations (e.g., dic(9;12)), aneuploidies (e.g., high hyperdiploidy) and copy number variations (e.g., IKZF1, PAX5) known from other techniques were also detected by OGM. Moreover, OGM was superior to well-established techniques for resolution of the more complex structure of a translocation t(12;21) and had a higher sensitivity for detection of copy number alterations. Importantly, a new and unknown gene fusion of JAK2 and NPAT due to a translocation t(9;11) was detected. We demonstrate the feasibility of OGM to detect well-established as well as new putative prognostic markers in an all-in-one approach in ALL. We hope that these limited results will be confirmed with testing of more samples in the future.

Identification of ROBO2 as a Potential Locus Associated with Inhaled Corticosteroid Response in Childhood Asthma.

Inhaled corticosteroids (ICS) are the most common asthma controller medication. An important contribution of genetic factors in ICS response has been evidenced. Here, we aimed to identify novel genetic markers involved in ICS response in asthma. A genome-wide association study (GWAS) of the change in lung function after 6 weeks of ICS treatment was performed in 166 asthma patients from the SLOVENIA study. Patients with an improvement in lung function ≥8% were considered as ICS responders. Suggestively associated variants (p-value ≤ 5 × 10-6) were evaluated in an independent study (n = 175). Validation of the association with asthma exacerbations despite ICS use was attempted in European (n = 2681) and admixed (n = 1347) populations. Variants previously associated with ICS response were also assessed for replication. As a result, the SNP rs1166980 from the ROBO2 gene was suggestively associated with the change in lung function (OR for G allele: 7.01, 95% CI: 3.29-14.93, p = 4.61 × 10-7), although this was not validated in CAMP. ROBO2 showed gene-level evidence of replication with asthma exacerbations despite ICS use in Europeans (minimum p-value = 1.44 × 10-5), but not in admixed individuals. The association of PDE10A-T with ICS response described by a previous study was validated. This study suggests that ROBO2 could be a potential novel locus for ICS response in Europeans.