Splicing analysis of STAT3 tandem donor suggests non-canonical binding registers for U1 and U6 snRNAs.

Tandem donor splice sites (5'ss) are unique regions with at least two GU dinucleotides serving as splicing cleavage sites. The Δ3 tandem 5'ss are a specific subclass of 5'ss separated by 3 nucleotides which can affect protein function by inserting/deleting a single amino acid. One 5'ss is typically preferred, yet factors governing particular 5'ss choice are not fully understood. A highly conserved exon 21 of the STAT3 gene was chosen as a model to study Δ3 tandem 5'ss splicing mechanisms. Based on multiple lines of experimental evidence, endogenous U1 snRNA most likely binds only to the upstream 5'ss. However, the downstream 5'ss is used preferentially, and the splice site choice is not dependent on the exact U1 snRNA binding position. Downstream 5'ss usage was sensitive to exact nucleotide composition and dependent on the presence of downstream regulatory region. The downstream 5'ss usage could be best explained by two novel interactions with endogenous U6 snRNA. U6 snRNA enables the downstream 5'ss usage in STAT3 exon 21 by two mechanisms: (i) binding in a novel non-canonical register and (ii) establishing extended Watson-Crick base pairing with the downstream regulatory region. This study suggests that U6:5'ss interaction is more flexible than previously thought.

LDLR gene rearrangements in Czech FH patients likely arise from one mutational event.

BACKGROUND: Large deletions and duplications within the low-density lipoprotein receptor (LDLR) gene make up approximately 10% of LDLR pathogenic variants found in Czech patients with familial hypercholesterolemia. The goal of this study was to test the hypothesis that all probands with each rearrangement share identical breakpoints inherited from a common ancestor and to determine the role of Alu repetitive elements in the generation of these rearrangements. METHODS: The breakpoint sequence was determined by PCR amplification and Sanger sequencing. To confirm the breakpoint position, an NGS analysis was performed. Haplotype analysis of common LDLR variants was performed using PCR and Sanger sequencing. RESULTS: The breakpoints of 8 rearrangements within the LDLR gene were analysed, including the four most common LDLR rearrangements in the Czech population (number of probands ranging from 8 to 28), and four less common rearrangements (1-4 probands). Probands with a specific rearrangement shared identical breakpoint positions and haplotypes associated with the rearrangement, suggesting a shared origin from a common ancestor. All breakpoints except for one were located inside an Alu element. In 6 out of 8 breakpoints, there was high homology (≥ 70%) between the two Alu repeats in which the break occurred. CONCLUSIONS: The most common rearrangements of the LDLR gene in the Czech population likely arose from one mutational event. Alu elements likely played a role in the generation of the majority of rearrangements inside the LDLR gene.

2023 Update on European Atherosclerosis Society Consensus Statement on Homozygous Familial Hypercholesterolaemia: new treatments and clinical guidance.

This 2023 statement updates clinical guidance for homozygous familial hypercholesterolaemia (HoFH), explains the genetic complexity, and provides pragmatic recommendations to address inequities in HoFH care worldwide. Key strengths include updated criteria for the clinical diagnosis of HoFH and the recommendation to prioritize phenotypic features over genotype. Thus, a low-density lipoprotein cholesterol (LDL-C) >10 mmol/L (>400 mg/dL) is suggestive of HoFH and warrants further evaluation. The statement also provides state-of-the art discussion and guidance to clinicians for interpreting the results of genetic testing and for family planning and pregnancy. Therapeutic decisions are based on the LDL-C level. Combination LDL-C-lowering therapy-both pharmacologic intervention and lipoprotein apheresis (LA)-is foundational. Addition of novel, efficacious therapies (i.e. inhibitors of proprotein convertase subtilisin/kexin type 9, followed by evinacumab and/or lomitapide) offers potential to attain LDL-C goal or reduce the need for LA. To improve HoFH care around the world, the statement recommends the creation of national screening programmes, education to improve awareness, and management guidelines that account for the local realities of care, including access to specialist centres, treatments, and cost. This updated statement provides guidance that is crucial to early diagnosis, better care, and improved cardiovascular health for patients with HoFH worldwide.

Worldwide experience of homozygous familial hypercholesterolaemia: retrospective cohort study.

BACKGROUND: Homozygous familial hypercholesterolaemia (HoFH) is a rare inherited disorder resulting in extremely elevated low-density lipoprotein cholesterol levels and premature atherosclerotic cardiovascular disease (ASCVD). Current guidance about its management and prognosis stems from small studies, mostly from high-income countries. The objective of this study was to assess the clinical and genetic characteristics, as well as the impact, of current practice on health outcomes of HoFH patients globally. METHODS: The HoFH International Clinical Collaborators registry collected data on patients with a clinical, or genetic, or both, diagnosis of HoFH using a retrospective cohort study design. This trial is registered with ClinicalTrials.gov, NCT04815005. FINDINGS: Overall, 751 patients from 38 countries were included, with 565 (75%) reporting biallelic pathogenic variants. The median age of diagnosis was 12·0 years (IQR 5·5-27·0) years. Of the 751 patients, 389 (52%) were female and 362 (48%) were male. Race was reported for 527 patients; 338 (64%) patients were White, 121 (23%) were Asian, and 68 (13%) were Black or mixed race. The major manifestations of ASCVD or aortic stenosis were already present in 65 (9%) of patients at diagnosis of HoFH. Globally, pretreatment LDL cholesterol levels were 14·7 mmol/L (IQR 11·6-18·4). Among patients with detailed therapeutic information, 491 (92%) of 534 received statins, 342 (64%) of 534 received ezetimibe, and 243 (39%) of 621 received lipoprotein apheresis. On-treatment LDL cholesterol levels were lower in high-income countries (3·93 mmol/L, IQR 2·6-5·8) versus non-high-income countries (9·3 mmol/L, 6·7-12·7), with greater use of three or more lipid-lowering therapies (LLT; high-income 66% vs non-high-income 24%) and consequently more patients attaining guideline-recommended LDL cholesterol goals (high-income 21% vs non-high-income 3%). A first major adverse cardiovascular event occurred a decade earlier in non-high-income countries, at a median age of 24·5 years (IQR 17·0-34·5) versus 37·0 years (29·0-49·0) in high-income countries (adjusted hazard ratio 1·64, 95% CI 1·13-2·38). INTERPRETATION: Worldwide, patients with HoFH are diagnosed too late, undertreated, and at high premature ASCVD risk. Greater use of multi-LLT regimens is associated with lower LDL cholesterol levels and better outcomes. Significant global disparities exist in treatment regimens, control of LDL cholesterol levels, and cardiovascular event-free survival, which demands a critical re-evaluation of global health policy to reduce inequalities and improve outcomes for all patients with HoFH. FUNDING: Amsterdam University Medical Centers, Location Academic Medical Center; Perelman School of Medicine at the University of Pennsylvania; and European Atherosclerosis Society.

Systematic Approach Revealed SERPING1 Splicing-Affecting Variants to be Highly Represented in the Czech National HAE Cohort.

Hereditary angioedema due to C1 inhibitor deficiency (C1-INH-HAE) is a rare and life-threatening condition characterized by recurrent localized edema. We conducted a systematic screening of SERPING1 defects in a cohort of 207 Czech patients from 85 families with C1-INH-HAE. Our workflow involved a combined strategy of sequencing extended to UTR and deep intronic regions, advanced in silico prediction tools, and mRNA-based functional assays. This approach allowed us to detect a causal variant in all families except one and to identify a total of 56 different variants, including 5 novel variants that are likely to be causal. We further investigated the functional impact of two splicing variants, namely c.550 + 3A > C and c.686-7C > G using minigene assays and RT-PCR mRNA analysis. Notably, our cohort showed a considerably higher proportion of detected splicing variants compared to other central European populations and the LOVD database. Moreover, our findings revealed a significant association between HAE type 1 missense variants and a delayed HAE onset when compared to null variants. We also observed a significant correlation between the presence of the SERPING1 variant c.-21 T > C in the trans position to causal variants and the frequency of attacks per year, disease onset, as well as Clinical severity score. Overall, our study provides new insights into the genetic landscape of C1-INH-HAE in the Czech population, including the identification of novel variants and a better understanding of genotype-phenotype correlations. Our findings also highlight the importance of comprehensive screening strategies and functional analyses in improving the C1-INH-HAE diagnosis and management.

PLAUR splicing pattern in hereditary angioedema patients' monocytes and macrophages.

BACKGROUND: The PLAUR gene encodes the urokinase-like plasminogen activator receptor (uPAR) and may undergo alternative splicing. Excluding cassette exons 3, 5 and 6 from the transcript results in truncated protein variants whose precise functions have not been elucidated yet. The PLAUR gene is one of several expressed in myeloid cells, where uPAR participates in different cellular processes, including the contact activation system and kallikrein-kinin system, which play an important role in hereditary angioedema (HAE) pathogenesis. A hypothesis about the PLAUR splicing pattern impact on HAE severity was tested. METHODS AND RESULTS: The RT-PCR quantified by capillary electrophoresis was used. Although no significant difference in alternative transcript frequency was observed between healthy volunteers and HAE patients, a significant increase in all cassette exon inclusion variants was revealed during monocyte-to-macrophage differentiation. CONCLUSIONS: PLAUR alternative splicing in monocytes and macrophages neither was different between HAE patients and healthy controls, nor reflected disease severity. However, the results showed an PLAUR splicing pattern was changing during monocyte-to-macrophage differentiation, but the significance of these changes is unknown and awaits future clarification.

The Clinical Genome Resource (ClinGen) Familial Hypercholesterolemia Variant Curation Expert Panel consensus guidelines for LDLR variant classification.

PURPOSE: In 2015, the American College of Medical Genetics and Genomics (ACMG) and the Association for Molecular Pathology (AMP) published consensus standardized guidelines for sequence-level variant classification in Mendelian disorders. To increase accuracy and consistency, the Clinical Genome Resource Familial Hypercholesterolemia (FH) Variant Curation Expert Panel was tasked with optimizing the existing ACMG/AMP framework for disease-specific classification in FH. In this study, we provide consensus recommendations for the most common FH-associated gene, LDLR, where >2300 unique FH-associated variants have been identified. METHODS: The multidisciplinary FH Variant Curation Expert Panel met in person and through frequent emails and conference calls to develop LDLR-specific modifications of ACMG/AMP guidelines. Through iteration, pilot testing, debate, and commentary, consensus among experts was reached. RESULTS: The consensus LDLR variant modifications to existing ACMG/AMP guidelines include (1) alteration of population frequency thresholds, (2) delineation of loss-of-function variant types, (3) functional study criteria specifications, (4) cosegregation criteria specifications, and (5) specific use and thresholds for in silico prediction tools, among others. CONCLUSION: Establishment of these guidelines as the new standard in the clinical laboratory setting will result in a more evidence-based, harmonized method for LDLR variant classification worldwide, thereby improving the care of patients with FH.

Nucleotides in both donor and acceptor splice sites are responsible for choice in NAGNAG tandem splice sites.

Among alternative splicing events in the human transcriptome, tandem NAGNAG acceptor splice sites represent an appreciable proportion. Both proximal and distal NAG can be used to produce two splicing isoforms differing by three nucleotides. In some cases, the upstream exon can be alternatively spliced as well, which further increases the number of possible transcripts. In this study, we showed that NAG choice in tandem splice site depends considerably not only on the concerned acceptor, but also on the upstream donor splice site sequence. Using an extensive set of experiments with systematically modified two-exonic minigene systems of AFAP1L2 or CSTD gene, we recognized the third and fifth intronic upstream donor splice site position and the tandem acceptor splice site region spanning from -10 to +2, including NAGNAG itself, as the main drivers. In addition, competition between different branch points and their composition were also shown to play a significant role in NAG choice. All these nucleotide effects appeared almost additive, which explained the high variability in proximal versus distal NAG usage.

Neutrophil and Granulocytic Myeloid-Derived Suppressor Cell-Mediated T Cell Suppression Significantly Contributes to Immune Dysregulation in Common Variable Immunodeficiency Disorders.

Common variable immunodeficiency disorders (CVID) represent a group of primary immunodeficiency diseases characterized by hypogammaglobulinemia and impaired specific Ab response, resulting in recurrent infections due to dysfunctional immune response. The specific mechanisms mediating immune deficiency in CVID remain to be determined. Previous studies indicated that immune dysregulation in CVID patients is associated with chronic microbial translocation, systemic immune activation, and altered homeostasis of lymphocytic and myeloid lineages. A detailed phenotypic, functional characterization of plasma markers and immune cell populations was performed in 46 CVID patients and 44 healthy donors. CVID patients displayed significantly elevated plasma levels of a marker of neutrophil activation neutrophil gelatinase-associated lipocalin. Neutrophils from CVID patients exhibited elevated surface levels of CD11b and PD-L1 and decreased levels of CD62L, CD16, and CD80, consistent with a phenotype of activated neutrophils with suppressive properties. Neutrophils from CVID patients actively suppressed T cell activation and release of IFN-γ via the production of reactive oxygen species. Furthermore, CVID was associated with an increased frequency of low-density neutrophils (LDNs)/granulocytic myeloid-derived suppressor cells. LDN/granulocytic myeloid-derived suppressor cell frequency in CVID patients correlated with reduced T cell responsiveness. Exogenous stimulation of whole blood with bacterial LPS emulated some but not all of the phenotypic changes observed on neutrophils from CVID patients and induced neutrophil population with LDN phenotype. The presented data demonstrate that neutrophils in the blood of CVID patients acquire an activated phenotype and exert potent T cell suppressive activity. Specific targeting of myeloid cell-derived suppressor activity represents a novel potential therapeutic strategy for CVID.

Deep Intronic Mutation in SERPING1 Caused Hereditary Angioedema Through Pseudoexon Activation.

PURPOSE: Hereditary angioedema (HAE) is a rare autosomal dominant life-threatening disease characterized by low levels of C1 inhibitor (type I HAE) or normal levels of ineffective C1 inhibitor (type II HAE), typically occurring as a consequence of a SERPING1 mutation. In some cases, a causal mutation remains undetected after using a standard molecular genetic analysis. RESULTS: Here we show a long methodological way to the final discovery of c.1029 + 384A > G, a novel deep intronic mutation in intron 6 which is responsible for HAE type I in a large family and has not been identified by a conventional diagnostic approach. This mutation results in de novo donor splice site creation and subsequent pseudoexon inclusion, the mechanism firstly described to occur in SERPING1 in this study. We additionally discovered that the proximal part of intron 6 is a region potentially prone to pseudoexon-activating mutations, since natural alternative exons and additional cryptic sites occur therein. Indeed, we confirmed the existence of at least two different alternative exons in this region not described previously. CONCLUSIONS: In conclusion, our results suggest that detecting aberrant transcripts, which are often low abundant because of nonsense-mediated decay, requires a modified methodological approach. We suggest SERPING1 intron 6 sequencing and/or tailored mRNA analysis to be routinely used in HAE patients with no mutation identified in the coding sequence.

The association between vegetation size and surgical treatment on 6-month mortality in left-sided infective endocarditis.

AIMS: In left-sided infective endocarditis (IE), a large vegetation >10 mm is associated with higher mortality, yet it is unknown whether surgery during the acute phase opposed to medical therapy is associated with improved survival. We assessed the association between surgery and 6-month mortality as related to vegetation size. METHODS AND RESULTS: Patients with definite, left-sided IE (2008-2012) from The International Collaboration on Endocarditis prospective, multinational registry were included. We compared clinical characteristics and 6-month mortality (by Cox regression with inverse propensity of treatment weighting) between patients with vegetation size ≤10 mm vs. >10 mm in maximum length by surgical treatment strategy. A total of 1006 patients with left sided IE were included; 422 with a vegetation size ≤10 mm (median age 66.0 years, 33% women) and 584 (median age 58.4 years, 34% women) patients with a large vegetation >10 mm. Operative risk by STS-IE score was similar between groups. Embolic events occurred in 28.4% vs. 44.3% (P < 0.001), respectively. Patients with a vegetation >10 mm was associated with higher 6-month mortality (25.1% vs. 19.4% for small vegetation, P = 0.035). However, after propensity adjustment, the association with higher mortality persisted only in patients with a large vegetation >10 mm vs. ≤10 mm: hazard ratio (HR) 1.55 (1.27-1.90); but only in patients with large vegetation managed medically [HR 1.86 (1.48-2.34)] rather than surgically [HR 1.01 (0.69-1.49)]. CONCLUSION: Left-sided IE with vegetation size >10 mm was associated with an increased mortality at 6 months in this observational study but was dependent on treatment strategy. For patients with large vegetation undergoing surgical treatment, survival was similar to patients with smaller vegetation size.

Splicing Enhancers at Intron-Exon Borders Participate in Acceptor Splice Sites Recognition.

Acceptor splice site recognition (3' splice site: 3'ss) is a fundamental step in precursor messenger RNA (pre-mRNA) splicing. Generally, the U2 small nuclear ribonucleoprotein (snRNP) auxiliary factor (U2AF) heterodimer recognizes the 3'ss, of which U2AF35 has a dual function: (i) It binds to the intron-exon border of some 3'ss and (ii) mediates enhancer-binding splicing activators' interactions with the spliceosome. Alternative mechanisms for 3'ss recognition have been suggested, yet they are still not thoroughly understood. Here, we analyzed 3'ss recognition where the intron-exon border is bound by a ubiquitous splicing regulator SRSF1. Using the minigene analysis of two model exons and their mutants, BRCA2 exon 12 and VARS2 exon 17, we showed that the exon inclusion correlated much better with the predicted SRSF1 affinity than 3'ss quality, which were assessed using the Catalog of Inferred Sequence Binding Preferences of RNA binding proteins (CISBP-RNA) database and maximum entropy algorithm (MaxEnt) predictor and the U2AF35 consensus matrix, respectively. RNA affinity purification proved SRSF1 binding to the model 3'ss. On the other hand, knockdown experiments revealed that U2AF35 also plays a role in these exons' inclusion. Most probably, both factors stochastically bind the 3'ss, supporting exon recognition, more apparently in VARS2 exon 17. Identifying splicing activators as 3'ss recognition factors is crucial for both a basic understanding of splicing regulation and human genetic diagnostics when assessing variants' effects on splicing.

Tangier disease in family with the phenotype of familial hypercholesterolemia.

Within the project MedPed (Make Early Diagnosis to Prevent Deaths) we have examined patient with familial hypercholesterolemia in our lipid ambulance. During the following investigation of the patients family we found out that her sister has on the contrary very low levels of  total and LDL-cholesterol. Concentration of  HDL-cholesterol was extreamly low (almost immeasurable). Differential diagnosis uttered a suspicion of rare form of familial hypoalfalipoproteinemia so-called Tangier disease. This suspicion was then confirmed by molecular genetic examination. Tangier disease is a rare lipoprotein metabolism disorder characterized biochemically by  almost complete absence of plasmatic HDL- cholesterol, extremely low level of apolipoprotein A-I and accumulation of cholesterol esters in macrophages. The first case was recorded on the Tangier island in 1961. In our research we describe the first case of a patient with homozygous form of Tangier disease in the history of the Czech Republic.

Inherited C2-complement deficiency: variable clinical manifestation (case reports and review).

C2 deficiency represents the most frequent type of a complement deficiency. Clinical manifestation includes infections caused by encapsulated bacteria (Steptococcus pneumoniae, Neisseria meningitidis) such as meningitis, gonitis, pneumonia or septicaemia. A causative treatment has not been available yet. A prophylactic vaccination and/or a long-term antibiotics prophylaxis are recommended. Here we report 2 patients from 2 unrelated families. The first patient suffered from recurrent otitis in his childhood. He underwent osteomyelitis, meningitis complicates with hear-loss, and one episode of pneumonia during adulthood. The second index patient underwent uncomplicated meningitis in his preschool age. He has been treated for recurrent upper-airways infections later. His sister has been completely asymptomatic. The deletion 28 bp (c.841-849+19del28) in C2-gene was detected in all of them in homozygous form. Our paper highlights the variability of a clinical manifestation in homozygous carriers, ranged from asymptomatic cases to patients with history of severe complications. The diagnosis is frequently made even in adulthood.

Fluorescent Capillary Electrophoresis Is Superior to Culture in Detecting Candida Species from Samples of Urinary Catheters and Ureteral Stents with Mono- or Polyfungal Biofilm Growth.

Molecular techniques in fungal detection and identification represent an efficient complementary diagnostic tool which is increasingly used to overcome limitations of routinely used culture techniques. The aim of this study was to characterize Candida sp. representation in samples from urine, urinary catheter, and ureteral stent biofilm using ITS2 ribosomal DNA (rDNA) amplification followed by fluorescent capillary electrophoresis (f-ITS2-PCR-CE) and to compare the results with those obtained by culture. A total of 419 samples were analyzed, and 106 (25.2%) were found positive, out of which 17 (16%) were polyfungal. The positivity rate did not differ between samples from catheters and stents (23.6% versus 20.9%) or between catheter and stent corresponding urine samples (40.2% versus 30.2%). Ten different Candida species were detected, with Candida parapsilosis (31.4%), Candida albicans (26.5%), and Candida tropicalis (12.4%) predominating. f-ITS2-PCR-CE was evaluated as substantially less time-consuming and 8.3 times more sensitive than the routinely applied culture technique with 1 µl of urine/sonicated fluid inoculated, detecting 67 (19.9%) versus 8 (2.4%) positive samples out of 337 initially analyzed samples. The culture sensitivity considerably improved to 1.7 times lower than that of f-ITS2-PCR-CE after the inoculation volume was increased to 100 µl in the additional 82 samples. Moreover, the molecular technique, unlike routine cultivation, enabled precise pathogen composition determination in polymicrobial samples. In conclusion, the f-ITS2-PCR-CE method was shown to be a quick and efficient tool for culture-independent detection and identification of fungi in urinary tract-related samples, demonstrating a higher sensitivity than culture.

Association between the timing of surgery for complicated, left-sided infective endocarditis and survival.

BACKGROUND: In patients with active infective endocarditis (IE), the relationship between timing of surgery and survival is uncertain. The objective was to evaluate clinical characteristics associated with timing of surgery and the association between surgical timing and 6-month survival in complicated, left-sided IE. METHODS: In a prospective, multicenter, observational registry (The International Collaboration on Endocarditis-PLUS, registry from 2008 to 2012), clinical factors associated with timing of surgery during the index hospitalization were determined among 485 adult patients with definite, complicated, left-sided IE who underwent cardiac surgery during their index hospitalization. The relationship between early surgical intervention (<7 days from admission to surgery center) and outcome after surgery was analyzed. The primary end point of the study was 6-month survival. RESULTS: The median time to surgery from admission to surgical center was 7 (interquartile range 2-15) days. Patients who underwent earlier surgery were more likely transferred to the surgical center (74.2% vs 46.4%, P < .001) and had a lower percentage of preexisting heart failure (before IE diagnosis) (6.0% vs 17.3%, P < .001) but higher rate of acute heart failure (53.2% vs 38.4%, P = .001). Variables independently associated with surgery <7 days from admission were patient transfer, acute heart failure, and nonelective surgical status (C-index = 0.84), but predicted operative risk was not. Cox proportional hazards modeling with inverse probability of treatment weighting found that earlier surgery was associated with a trend toward higher 6-month mortality compared with later surgery (hazard ratio = 1.68, 95% CI 0.97-2.96; P = .065), particularly surgery within 2 days of admission or transfer. Mortality was significantly associated with operative risk and complicated IE, including Staphylococcus aureus infection and presence of abscess. CONCLUSIONS: Earlier surgery in IE is strongly associated with acute heart failure and surgical urgency. After adjustment for operative risk and IE complications, earlier surgery <7 days from admission was associated with a trend toward higher 6-month overall mortality compared with surgery later in the index hospitalization.

The Impact of the International Cooperation On Familial Hypercholesterolemia Screening and Treatment: Results from the ScreenPro FH Project.

PURPOSE OF REVIEW: Familial hypercholesterolemia (FH) is often perceived and described as underdiagnosed and undertreated, though effective treatment of FH is available. Owing to the mentioned facts, it is ever more imperative to screen and treat FH patients. Subsequent to the identification of patients, the project focuses on the improvement of their prognoses. The ScreenPro FH project was established as a functional international network for the diagnosis, screening, and treatment of FH. Individual countries were assigned goals, e.g., to define the actual situation and available treatment. With "central support," more centers and countries participated in the project. Subsequently, individual countries reported the results at the beginning and end of the project. Collected data were statistically evaluated. RECENT FINDINGS: The increasing number of patients in databases, from 7500 in 2014 to 25,347 in 2018, demonstrates the improvement in overall effectiveness, as well as an increase in the number of centers from 70 to 252. Before all, LDL-C decreased by 41.5% and total cholesterol by 32.3%. As data from all countries and patients were not available at the time of the analysis, only those results from 10 countries and 5585 patients at the beginning of the project and at the time of writing are included. Our data are quite positive. However, our results have only limited validity. Our patients are far from the target levels of LDL-C. The situation can be improved with the introduction of new therapy, PCSK9-i, evolocumab, and alirocumab. International cooperation improved the screening of FH and finally led to an improvement in cardiovascular risk.

High-throughput analysis revealed mutations' diverging effects on SMN1 exon 7 splicing.

Splicing-affecting mutations can disrupt gene function by altering the transcript assembly. To ascertain splicing dysregulation principles, we modified a minigene assay for the parallel high-throughput evaluation of different mutations by next-generation sequencing. In our model system, all exonic and six intronic positions of the SMN1 gene's exon 7 were mutated to all possible nucleotide variants, which amounted to 180 unique single-nucleotide mutants and 470 double mutants. The mutations resulted in a wide range of splicing aberrations. Exonic splicing-affecting mutations resulted either in substantial exon skipping, supposedly driven by predicted exonic splicing silencer or cryptic donor splice site (5'ss) and de novo 5'ss strengthening and use. On the other hand, a single disruption of exonic splicing enhancer was not sufficient to cause major exon skipping, suggesting these elements can be substituted during exon recognition. While disrupting the acceptor splice site led only to exon skipping, some 5'ss mutations potentiated the use of three different cryptic 5'ss. Generally, single mutations supporting cryptic 5'ss use displayed better pre-mRNA/U1 snRNA duplex stability and increased splicing regulatory element strength across the original 5'ss. Analyzing double mutants supported the predominating splicing regulatory elements' effect, but U1 snRNA binding could contribute to the global balance of splicing isoforms. Based on these findings, we suggest that creating a new splicing enhancer across the mutated 5'ss can be one of the main factors driving cryptic 5'ss use.

Impact of acceptor splice site NAGTAG motif on exon recognition.

Pre-mRNA splicing is an essential step in gene expression, when introns are removed and exons joined by the complex of proteins called spliceosome. Correct splicing requires a precise exon/intron junction definition, which is determined by a consensual donor and acceptor splice site at the 5' and 3' end, respectively. An acceptor splice site (3'ss) consists of highly conserved AG nucleotides in positions E-2 and E-1. These nucleotides can appear in tandem, located 3 bp from each other. Then they are referred to as NAGNAG or tandem 3'ss, which can be alternatively spliced. NAG/TAG 3'ss motif abundance is extremely low and cannot be easily explained by just a nucleotide preference in this position. We tested artificial NAG/TAG motif's potential negative effect on exon recognition using a minigene assay. Introducing the NAG/TAG motif into seven different exons revealed no general negative effect on exon recognition. The only observed effect was the partial use of the newly formed distal 3'ss. We can conclude that this motif's extremely low preference in a natural 3'ss is not a consequence of the NAG/TAG motif's negative effect on exon recognition, but more likely the result of other RNA processing aspects, such as an alternative 3'ss choice, decreased 3'ss strength, or incorporating an amber stop codon.

Neutrophils Are Dysregulated in Patients with Hereditary Angioedema Types I and II in a Symptom-Free Period.

Neutrophils impact on processes preceding the formation of bradykinin, a major swelling mediator in hereditary angioedema (HAE), yet their potential role in HAE pathogenesis has not been sufficiently studied. We assessed the relative mRNA expression of 10 genes related to neutrophil activation using RNA extracted from the peripheral blood neutrophils of 23 HAE patients in a symptom-free period and 39 healthy donors. Increased relative mRNA expression levels of CD274, IL1B, IL1RN, IL8, MMP9, and TLR4, together with a lack in their mutual correlations detected in HAE patients compared to healthy controls, suggested a preactivated state and dysregulation of patients' neutrophils. Patients' neutrophil-alerted state was further supported by increased CD11b, decreased CD16 plasma membrane deposition, and increased relative CD274+ and CD87+ neutrophil counts, but not by increased neutrophil elastase or myeloperoxidase plasma levels. As CD274 mediates inhibitory signals to different immune cells, neutrophils were cocultured with T-cells/PBMC. The decrease in CD25+ and IFN-γ + T-cell/PBMC ratio in patients indicated the patients' neutrophil suppressive functions. In summary, the results showed neutrophils' alerted state and dysregulation at the transcript level in patients with HAE types I and II even in a symptom-free period, which might make them more susceptible to edema formation. Neutrophils' T-cell suppressive capacity in HAE patients needs to be further investigated.