TY - JOUR A1 - Rost, Simone A1 - Müller, Elisabeth A1 - Keller, Alexander A1 - Fregin, Andreas A1 - Müller, Clemens R. T1 - Confirmation of warfarin resistance of naturally occurring VKORC1 variants by coexpression with coagulation factor IX and in silico protein modelling N2 - Background VKORC1 has been identified some years ago as the gene encoding vitamin K epoxide reductase (VKOR) – the target protein for coumarin derivates like warfarin or phenprocoumon. Resistance against warfarin and other coumarin-type anticoagulants has been frequently reported over the last 50 years in rodents due to problems in pest control as well as in thrombophilic patients showing variable response to anticoagulant treatment. Many different mutations have already been detected in the VKORC1 gene leading to warfarin resistance in rats, mice and in humans. Since the conventional in vitro dithiothreitol (DTT)-driven VKOR enzymatic assay often did not reflect the in vivo status concerning warfarin resistance, we recently developed a cell culture-based method for coexpression of VKORC1 with coagulation factor IX and subsequent measurement of secreted FIX in order to test warfarin inhibition in wild-type and mutated VKORC1. Results In the present study, we coexpressed wild-type factor IX with 12 different VKORC1 variants which were previously detected in warfarin resistant rats and mice. The results show that amino acid substitutions in VKORC1 maintain VKOR activity and are associated with warfarin resistance. When we projected in silico the amino acid substitutions onto the published three-dimensional model of the bacterial VKOR enzyme, the predicted effects matched well the catalytic mechanism proposed for the bacterial enzyme. Conclusions The established cell-based system for coexpression of VKORC1 and factor IX uses FIX activity as an indicator of carboxylation efficiency. This system reflects the warfarin resistance status of VKORC1 mutations from anticoagulant resistant rodents more closely than the traditional DTT-driven enzyme assay. All mutations studied were also predicted to be involved in the reaction mechanism. KW - VKORC1 KW - Vitamin K epoxide reductase KW - Anticoagulants KW - Warfarin KW - Coumarin KW - Coexpression KW - Coagulation factor IX Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-110095 ER - TY - THES A1 - Rost, Simone Esther T1 - Molekulare Ursachen Vitamin K-abhängiger Gerinnungsstörungen T1 - Molecular Causes of Vitamin K-dependent Coagulation Disorders N2 - Vitamin K ist ein essentieller Cofaktor für die posttranslationale Gamma-Carboxylierung von sog. Vitamin K-abhängigen Gerinnungsfaktoren, Knochenproteinen, Zellwachstum-regulierenden und weiteren Proteinen mit noch unbekannter Funktion. Defekte im Vitamin K-Stoffwechsel führen einerseits zu zwei verschiedenen Formen des familiären Mangels aller Vitamin K-abhängigen Gerinnungsfaktoren (VKCFD1 und 2) und andererseits zur Resistenz oder Hypersensitivität gegenüber Cumarinderivaten, wie Warfarin, die als Vitamin K-Antagonisten zur Antikoagulationstherapie bei thromboembolischen Erkrankungen, aber auch zur Bekämpfung von Ratten und Mäusen eingesetzt werden. Die Aufklärung und Charakterisierung der molekularen Ursachen dieser Erkrankungen wird in dieser Doktorarbeit anhand von Veröffentlichungen dokumentiert. Ausgehend von der Charakterisierung zweier Familien mit dem VKCFD2-Phänotyp, wird die Kartierung des VKCFD2-Locus auf dem kurzen Arm von Chromosom 16 beschrieben. Durch eine systematische Mutationssuche in der ca. 130 Gene umfassenden Kandidatenregion von Chromosom 16 konnte das für diese Erkrankung und die Warfarinresistenz ursächliche Gen ausfindig gemacht werden. Dabei handelt es sich um das Gen für die entscheidende Komponente der Vitamin K-Epoxid-Reduktase (VKORC1), die den Recycling-Prozess von Vitamin K im sog. Vitamin K-Zyklus katalysiert. Die Charakterisierung des VKORC1-Proteins umfasst dessen subzelluläre Lokalisation, den Vergleich orthologer Proteine in verschiedenen Species und die funktionelle Charakterisierung von rekombinant exprimiertem VKORC1. Durch positionsspezifische Mutagenesen und anschließende Expression in humanen Nierenzellen konnten mehrere für die Funktion der VKORC1 relevante Aminosäuren identifiziert werden. Die posttranslationale Modifikation der Vitamin K-abhängigen Proteine wird von der Gamma-Glutamyl-Carboxylase (GGCX) katalysiert. Defekte in diesem Enzym wurden von zwei verschiedenen Arbeitsgruppen als Ursache für die erste Form der VKCFD-Erkrankung nachgewiesen. In dieser Doktorarbeit werden drei weitere, von unserer Arbeitsgruppe identifizierte Mutationen im GGCX-Gen beschrieben, unter denen sich ein nachgewiesener Founder-Effekt an Position 485 des Proteins befindet. Die Arg485Pro-Variante wurde rekombinant in Insektenzellen exprimiert und konnte mittels kinetischer Studien als VKCFD1-verursachende Mutation verifiziert werden. N2 - Vitamin K is an essential cofactor for the posttranslational gamma-carboxylation of the so-called vitamin K-dependent coagulation factors, bone proteins, cell growth regulating proteins and others of unknown function. Defects in vitamin K metabolism cause two different forms of combined deficiency of vitamin K-dependent coagulation factors (VKCFD type 1 and type 2) as well as resistance or hypersensitivity to coumarin derivates, such as warfarin, which act as vitamin K antagonists. Coumarins are used for anticoagulation therapy of thromboembolic diseases and in higher dosis also for rodent pest control. The aim of this thesis is to characterize the molecular basis of these diseases. This work has led to six publications. The VKCFD type 2 phenotype as described in two unrelated families was used to perform a homozygosity mapping of the VKCFD2 locus on the short arm of chromosome 16. A systematic mutation screening in the candidate region on chromosome 16 comprising approximately 130 putative genes resulted in the identification of the gene causative for VKCFD2 and the allelic phenotype warfarin resistance. This gene encodes the first identified component of the vitamin K epoxide reductase (VKORC1) which catalyzes the reduction of vitamin K epoxide as an important part of the so-called vitamin K cycle. Characterization of the VKORC1 protein includes its subcellular localization, comparison of orthologous proteins in different species and functional studies of the recombinant VKORC1. Amino acids which are relevant for protein structure or function were identified by site-directed mutagenesis experiments and subsequent expression in human embryonic kidney cells (HEK293). Posttranslational modification of the vitamin K-dependent proteins is catalysed by the gamma-glutamyl carboxylase (GGCX), an enzyme of the endoplasmic reticulum. Mutations in the gene encoding this enzyme were demonstrated to be causative for VKCFD type 1 by two different working groups. Our working group identified three additional mutations in the GGCX gene. Recurrent mutations at position 485 of the protein were shown to result from a founder effect. The Arg485Pro variant was recombinantly expressed in insect cells using the baculovirus system and could be verified as a causative mutation for the VKCFD1 phenotype by kinetic studies. KW - Koagulopathie KW - Vitamin-K-Gruppe KW - Genanalyse KW - Vitamin K KW - Blutgerinnung KW - VKORC1 KW - Warfarin KW - Gamma-Carboxylase KW - phylloquinone KW - blood coagulation KW - VKCFD KW - coumarin KW - gamma-carboxylation Y1 - 2006 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-17589 ER - TY - JOUR A1 - Zaum, Ann‐Kathrin A1 - Nanda, Indrajit A1 - Kress, Wolfram A1 - Rost, Simone T1 - Detection of pericentric inversion with breakpoint in DMD by whole genome sequencing JF - Molecular Genetics & Genomic Medicine N2 - Background Dystrophinopathies caused by variants in the DMD gene are a well‐studied muscle disease. The most common type of variant in DMD are large deletions. Very rarely reported forms of variants are chromosomal translocations, inversions and deep intronic variants (DIVs) because they are not detectable by standard diagnostic techniques (sequencing of coding sequence, copy number variant detection). This might be the reason that some clinically and histologically proven dystrophinopathy cases remain unsolved. Methods We used whole genome sequencing (WGS) to screen the entire DMD gene for variants in one of two brothers suffering from typical muscular dystrophy with strongly elevated creatine kinase levels. Results Although a pathogenic DIV could not be detected, we were able to identify a pericentric inversion with breakpoints in DMD intron 44 and Xq13.3, which could be confirmed by Sanger sequencing in the index as well as in his brother and mother. As this variation affects a major part of DMD it is most likely disease causing. Conclusion Our findings elucidate that WGS is capable of detecting large structural rearrangements and might be suitable for the genetic diagnostics of dystrophinopathies in the future. In particular, inversions might be a more frequent cause for dystrophinopathies as anticipated and should be considered in genetically unsolved dystrophinopathy cases. KW - chromosome inversion KW - Duchenne muscular dystrophy KW - dystrophin KW - genetic diagnostics KW - whole genome sequencing Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-293940 VL - 10 IS - 10 ER - TY - JOUR A1 - Kolokotronis, Konstantinos A1 - Pluta, Natalie A1 - Klopocki, Eva A1 - Kunstmann, Erdmute A1 - Messroghli, Daniel A1 - Maack, Christoph A1 - Tejman-Yarden, Shai A1 - Arad, Michael A1 - Rost, Simone A1 - Gerull, Brenda T1 - New Insights on Genetic Diagnostics in Cardiomyopathy and Arrhythmia Patients Gained by Stepwise Exome Data Analysis JF - Journal of Clinical Medicine N2 - Inherited cardiomyopathies are characterized by clinical and genetic heterogeneity that challenge genetic diagnostics. In this study, we examined the diagnostic benefit of exome data compared to targeted gene panel analyses, and we propose new candidate genes. We performed exome sequencing in a cohort of 61 consecutive patients with a diagnosis of cardiomyopathy or primary arrhythmia, and we analyzed the data following a stepwise approach. Overall, in 64% of patients, a variant of interest (VOI) was detected. The detection rate in the main sub-cohort consisting of patients with dilated cardiomyopathy (DCM) was much higher than previously reported (25/36; 69%). The majority of VOIs were found in disease-specific panels, while a further analysis of an extended panel and exome data led to an additional diagnostic yield of 13% and 5%, respectively. Exome data analysis also detected variants in candidate genes whose functional profile suggested a probable pathogenetic role, the strongest candidate being a truncating variant in STK38. In conclusion, although the diagnostic yield of gene panels is acceptable for routine diagnostics, the genetic heterogeneity of cardiomyopathies and the presence of still-unknown causes favor exome sequencing, which enables the detection of interesting phenotype–genotype correlations, as well as the identification of novel candidate genes. KW - cardiomyopathy KW - cardiogenetics KW - whole exome sequencing KW - targeted gene panel KW - candidate genes Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-236094 VL - 9 IS - 7 ER - TY - JOUR A1 - Wagenhäuser, Laura A1 - Rickert, Vanessa A1 - Sommer, Claudia A1 - Wanner, Christoph A1 - Nordbeck, Peter A1 - Rost, Simone A1 - Üçeyler, Nurcan T1 - X-chromosomal inactivation patterns in women with Fabry disease JF - Molecular Genetics & Genomic Medicine N2 - Background Although Fabry disease (FD) is an X-linked lysosomal storage disorder caused by mutations in the α-galactosidase A gene (GLA), women may develop severe symptoms. We investigated X-chromosomal inactivation patterns (XCI) as a potential determinant of symptom severity in FD women. Patients and Methods We included 95 women with mutations in GLA (n = 18 with variants of unknown pathogenicity) and 50 related men, and collected mouth epithelial cells, venous blood, and skin fibroblasts for XCI analysis using the methylation status of the androgen receptor gene. The mutated X-chromosome was identified by comparison of samples from relatives. Patients underwent genotype categorization and deep clinical phenotyping of symptom severity. Results 43/95 (45%) women carried mutations categorized as classic. The XCI pattern was skewed (i.e., ≥75:25% distribution) in 6/87 (7%) mouth epithelial cell samples, 31/88 (35%) blood samples, and 9/27 (33%) skin fibroblast samples. Clinical phenotype, α-galactosidase A (GAL) activity, and lyso-Gb3 levels did not show intergroup differences when stratified for X-chromosomal skewing and activity status of the mutated X-chromosome. Conclusions X-inactivation patterns alone do not reliably reflect the clinical phenotype of women with FD when investigated in biomaterial not directly affected by FD. However, while XCI patterns may vary between tissues, blood frequently shows skewing of XCI patterns. KW - Fabry disease KW - Fabry genotype KW - Fabry phenotype KW - female Fabry patients KW - X-chromosomal inactivation Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-312795 VL - 10 IS - 9 ER - TY - JOUR A1 - Mahyera, Alexis S. A1 - Schneider, Tamara A1 - Halliger-Keller, Birgit A1 - Schrooten, Katja A1 - Hörner, Eva-Maria A1 - Rost, Simone A1 - Kress, Wolfram T1 - Distribution and Structure of DM2 Repeat Tract Alleles in the German Population JF - Frontiers in Neurology N2 - Autosomal dominant inherited Myotonic dystrophy type 1 and 2 (DM1 and DM2) are the most frequent muscle dystrophies in the European population and are caused by repeat expansion mutations. For Germany cumulative empiric evidence suggests an estimated prevalence of DM2 of roughly 9 in 100,000, therefore being as prevalent as DM1. In DM2, a (CCTG)n repeat tract located in the first intron of the CNBP gene is expanded. The CCTG repeat tract is part of a complex repeat structure comprising not only CCTG tetraplets but also repeated TG dinucleotides and TCTG tetraplet elements as well as NCTG interruptions. Here, we provide the distribution of normal sized alleles in the German population, which was found to be highly similar to the Slovak population. Sequencing of 34 unexpanded healthy range alleles in DM2 positive patients (heterozygous for a full expansion) revealed that the CCTG repeat tract is usually interrupted by at least three tetraplets which according to current opinion is supposed to render it stable against expansion. Interestingly, only the largest analyzed normal allele had 23 uninterrupted CCTGs and consequently could represent an instable early premutation allele. In our diagnostic history of DM2 cases, a total of 18 premutations were detected in 16 independent cases. Here, we describe two premutation families, one with an expansion from a premutation allele and the other with a contraction of a full expansion down to a premutation allele. Our diagnostic results support the general assumption that the premutation range of unstable CCTG stretches lies obviously between 25 and 75 CCTGs. However, the clinical significance of premutation alleles is still unclear. In the light of the two described families we suggest incomplete penetrance. Thus, as it was proposed for other repeat expansion diseases (e.g., Huntington's disease), a fluid transition of penetrance is more likely rather than a clear cut CCTG number threshold. KW - DM2 KW - intergenerational contraction KW - expansion KW - premutation KW - penetrance KW - prevalence Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-196252 SN - 1664-2295 VL - 9 IS - 463 ER - TY - JOUR A1 - Weißbach, Susann A1 - Heredia-Guerrero, Sofia Catalina A1 - Barnsteiner, Stefanie A1 - Großhans, Lukas A1 - Bodem, Jochen A1 - Starz, Hanna A1 - Langer, Christian A1 - Appenzeller, Silke A1 - Knop, Stefan A1 - Steinbrunn, Torsten A1 - Rost, Simone A1 - Einsele, Hermann A1 - Bargou, Ralf Christian A1 - Rosenwald, Andreas A1 - Stühmer, Thorsten A1 - Leich, Ellen T1 - Exon-4 Mutations in KRAS Affect MEK/ERK and PI3K/AKT Signaling in Human Multiple Myeloma Cell Lines JF - Cancers N2 - Approximately 20% of multiple myeloma (MM) cases harbor a point mutation in KRAS. However, there is still no final consent on whether KRAS-mutations are associated with disease outcome. Specifically, no data exist on whether KRAS-mutations have an impact on survival of MM patients at diagnosis in the era of novel agents. Direct blockade of KRAS for therapeutic purposes is mostly impossible, but recently a mutation-specific covalent inhibitor targeting KRAS\(^{p.G12C}\) entered into clinical trials. However, other KRAS hotspot-mutations exist in MM patients, including the less common exon-4 mutations. For the current study, the coding regions of KRAS were deep-sequenced in 80 newly diagnosed MM patients, uniformely treated with three cycles of bortezomib plus dexamethasone and cyclophosphamide (VCD)-induction, followed by high-dose chemotherapy and autologous stem cell transplantation. Moreover, the functional impact of KRAS\(^{p.G12A}\) and the exon-4 mutations p.A146T and p.A146V on different survival pathways was investigated. Specifically, KRAS\(^{WT}\), KRAS\(^{p.G12A}\), KRAS\(^{p.A146T}\), and KRAS\(^{p.A146V}\) were overexpressed in HEK293 cells and the KRAS\(^{WT}\) MM cell lines JJN3 and OPM2 using lentiviral transduction and the Sleeping Beauty vector system. Even though KRAS-mutations were not correlated with survival, all KRAS-mutants were found capable of potentially activating MEK/ERK- and sustaining PI3K/AKT-signaling in MM cells. KW - multiple myeloma KW - KRAS KW - MEK/ERK-signaling KW - AKT-signaling KW - amplicon sequencing Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-200617 SN - 2072-6694 VL - 12 IS - 2 ER - TY - JOUR A1 - Janz, Anna A1 - Zink, Miriam A1 - Cirnu, Alexandra A1 - Hartleb, Annika A1 - Albrecht, Christina A1 - Rost, Simone A1 - Klopocki, Eva A1 - Günther, Katharina A1 - Edenhofer, Frank A1 - Ergün, Süleyman A1 - Gerull, Brenda T1 - CRISPR/Cas9-edited PKP2 knock-out (JMUi001-A-2) and DSG2 knock-out (JMUi001-A-3) iPSC lines as an isogenic human model system for arrhythmogenic cardiomyopathy (ACM) JF - Stem Cell Research N2 - Arrhythmogenic cardiomyopathy (ACM) is characterized by fibro-fatty replacement of the myocardium, heart failure and life-threatening ventricular arrhythmias. Causal mutations were identified in genes encoding for proteins of the desmosomes, predominantly plakophilin-2 (PKP2) and desmoglein-2 (DSG2). We generated gene-edited knock-out iPSC lines for PKP2 (JMUi001-A-2) and DSG2 (JMUi001-A-3) using the CRISPR/Cas9 system in a healthy control iPSC background (JMUi001A). Stem cell-like morphology, robust expression of pluripotency markers, embryoid body formation and normal karyotypes confirmed the generation of high quality iPSCs to provide a novel isogenic human in vitro model system mimicking ACM when differentiated into cardiomyocytes. KW - mutations Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-259846 VL - 53 ER - TY - JOUR A1 - Pluta, Natalie A1 - Hoffjan, Sabine A1 - Zimmer, Frederic A1 - Köhler, Cornelia A1 - Lücke, Thomas A1 - Mohr, Jennifer A1 - Vorgerd, Matthias A1 - Nguyen, Hoa Huu Phuc A1 - Atlan, David A1 - Wolf, Beat A1 - Zaum, Ann-Kathrin A1 - Rost, Simone T1 - Homozygous inversion on chromosome 13 involving SGCG detected by short read whole genome sequencing in a patient suffering from limb-girdle muscular dystrophy JF - Genes N2 - New techniques in molecular genetic diagnostics now allow for accurate diagnosis in a large proportion of patients with muscular diseases. Nevertheless, many patients remain unsolved, although the clinical history and/or the muscle biopsy give a clear indication of the involved genes. In many cases, there is a strong suspicion that the cause must lie in unexplored gene areas, such as deep-intronic or other non-coding regions. In order to find these changes, next-generation sequencing (NGS) methods are constantly evolving, making it possible to sequence entire genomes to reveal these previously uninvestigated regions. Here, we present a young woman who was strongly suspected of having a so far genetically unsolved sarcoglycanopathy based on her clinical history and muscle biopsy. Using short read whole genome sequencing (WGS), a homozygous inversion on chromosome 13 involving SGCG and LINC00621 was detected. The breakpoint in intron 2 of SGCG led to the absence of γ-sarcoglycan, resulting in the manifestation of autosomal recessive limb-girdle muscular dystrophy 5 (LGMDR5) in the young woman. KW - inversion KW - sarcoglycanopathy KW - whole genome sequencing (WGS) KW - next generation sequencing (NGS) KW - LGMDR5 KW - muscle disease KW - genetic diagnostics Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-288122 SN - 2073-4425 VL - 13 IS - 10 ER -