0000000000211067

AUTHOR

Michael Knapp

showing 13 related works from this author

Common variants in the HLA-DQ region confer susceptibility to idiopathic achalasia

2014

Idiopathic achalasia is characterized by a failure of the lower esophageal sphincter to relax due to a loss of neurons in the myenteric plexus(1,2). This ultimately leads to massive dilatation and an irreversibly impaired megaesophagus. We performed a genetic association study in 1,068 achalasia cases and 4,242 controls and fine-mapped a strong MHC association signal by imputing classical HLA haplotypes and amino acid polymorphisms. An eight-residue insertion at position 227-234 in the cytoplasmic tail of HLA-DQ beta 1 (encoded by HLA-DQB1*05:03 and HLA-DQB1*06:01) confers the strongest risk for achalasia (P = 1.73 x 10(-19)). In addition, two amino acid substitutions in the. extracellular …

MaleModels MolecularAchalasiaImmunogeneticsBiologyMajor histocompatibility complexPolymorphism Single Nucleotidedigestive systemHLA-DQ alpha-ChainsHLA-DQ AntigensHLA-DQotorhinolaryngologic diseasesGeneticsmedicineHLA-DQ beta-ChainsHumansGenetic Predisposition to DiseaseEsophagusAllelesGenetic Association StudiesGenetic associationGeneticsAchalasiaMotility disorderASSOCIATIONmedicine.diseasedigestive system diseasesEsophageal AchalasiaINSIGHTSLogistic Modelsmedicine.anatomical_structureAmino Acid SubstitutionHaplotypesCase-Control StudiesImmunologybiology.proteinFemaleIdiopathic achalasiageneticMHCNature Genetics
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Shared Genetic Etiology of Obesity-Related Traits and Barrett's Esophagus/Adenocarcinoma: Insights from Genome-Wide Association Studies

2020

Abstract Background: Obesity is a major risk factor for esophageal adenocarcinoma (EA) and its precursor Barrett's esophagus (BE). Research suggests that individuals with high genetic risk to obesity have a higher BE/EA risk. To facilitate understanding of biological factors that lead to progression from BE to EA, the present study investigated the shared genetic background of BE/EA and obesity-related traits. Methods: Cross-trait linkage disequilibrium score regression was applied to summary statistics from genome-wide association meta-analyses on BE/EA and on obesity traits. Body mass index (BMI) was used as a proxy for general obesity, and waist-to-hip ratio (WHR) for abdominal obesity. …

Male0301 basic medicineOncologymedicine.medical_specialtyEsophageal NeoplasmsEpidemiologyQuantitative Trait LocieducationMedizinMEDLINEGenome-wide association studyAdenocarcinomaPolymorphism Single NucleotideRisk AssessmentLinkage DisequilibriumBody Mass IndexBarrett Esophagus03 medical and health sciencesSex Factors0302 clinical medicineMeta-Analysis as TopicRisk FactorsInternal medicineHumansMedicineGenetic Predisposition to DiseaseObesityEsophagusWaist-Hip Ratiobusiness.industryEsophageal cancermedicine.diseaseMedical researchObesityRenal disorders Radboud Institute for Molecular Life Sciences [Radboudumc 11]030104 developmental biologymedicine.anatomical_structureOncology030220 oncology & carcinogenesisBarrett's esophagusDisease ProgressionAdenocarcinomaFemalebusinessGenome-Wide Association StudyCancer Epidemiology, Biomarkers & Prevention
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The Barrett‐associated variants at GDF 7 and TBX 5 also increase esophageal adenocarcinoma risk

2016

Barrett's esophagus (BE) and esophageal adenocarcinoma (EAC) represent two stages within the esophagitis-metaplasia-dysplasia-adenocarcinoma sequence. Previously genetic risk factors have been identified that confer risk to BE and EAC development. However, to which extent the genetic variants confer risk to different stages of the BE/EAC sequence remains mainly unknown. In this study we analyzed three most recently identified BE variants at the genes GDF7 (rs3072), TBX5 (rs2701108), and ALDH1A2 (rs3784262) separately in BE and EAC samples in order to determine their risk effects during BE/EAC sequence. Our data show that rs3072 at GDF7 and rs2701108 at TBX5 are also associated with EAC and …

0301 basic medicineCancer ResearchCase-control studyGenome-wide association studyLocus (genetics)Biologymedicine.diseaseBioinformaticshumanitiesALDH1A203 medical and health sciences030104 developmental biologymedicine.anatomical_structureOncologyGenetic variationCancer researchmedicineAdenocarcinomaRadiology Nuclear Medicine and imagingEsophagusGeneCancer Medicine
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Evidence for PTGER4, PSCA and MBOAT7 as risk genes for gastric cancer on the genome and transcriptome level

2017

TranscriptomeGeneticsmedicineCancerBiologymedicine.diseaseGeneGenome72. Jahrestagung der Deutschen Gesellschaft für Gastroenterologie, Verdauungs- und Stoffwechselkrankheiten mit Sektion Endoskopie – 11. Herbsttagung der Deutschen Gesellschaft für Allgemein- und Viszeralchirurgie gemeinsam mit den Arbeitsgemeinschaften der DGAV
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Genome-wide Association Study and Meta-Analysis Identify ISL1 as Genome-wide Significant Susceptibility Gene for Bladder Exstrophy

2015

The bladder exstrophy-epispadias complex (BEEC) represents the severe end of the uro-rectal malformation spectrum, and is thought to result from aberrant embryonic morphogenesis of the cloacal membrane and the urorectal septum. The most common form of BEEC is isolated classic bladder exstrophy (CBE). To identify susceptibility loci for CBE, we performed a genome-wide association study (GWAS) of 110 CBE patients and 1,177 controls of European origin. Here, an association was found with a region of approximately 220kb on chromosome 5q11.1. This region harbors the ISL1 (ISL LIM homeobox 1) gene. Multiple markers in this region showed evidence for association with CBE, including 84 markers with…

Cancer ResearchCandidate genelcsh:QH426-470LIM-Homeodomain ProteinsMedizinLocus (genetics)Genome-wide association study-BiologyMiceUrorectal septumMedizinische FakultätEmbryonic morphogenesisGeneticsmedicineAnimalsHumansddc:610Molecular BiologyGeneGenetics (clinical)Ecology Evolution Behavior and SystematicsGeneticsBladder Exstrophymedicine.diseaseBladder exstrophylcsh:GeneticsCase-Control StudiesChromosomal regionGenome-Wide Association StudyTranscription FactorsResearch ArticlePLOS Genetics
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Germline variation in the insulin-like growth factor pathway and risk of Barrett's esophagus and esophageal adenocarcinoma

2020

Contains fulltext : 235640.pdf (Publisher’s version ) (Closed access) Genome-wide association studies (GWAS) of esophageal adenocarcinoma (EAC) and its precursor, Barrett's esophagus (BE), have uncovered significant genetic components of risk, but most heritability remains unexplained. Targeted assessment of genetic variation in biologically relevant pathways using novel analytical approaches may identify missed susceptibility signals. Central obesity, a key BE/EAC risk factor, is linked to systemic inflammation, altered hormonal signaling and insulin-like growth factor (IGF) axis dysfunction. Here, we assessed IGF-related genetic variation and risk of BE and EAC. Principal component analys…

0301 basic medicineOncologyMaleCancer Researchmedicine.medical_specialtyEsophageal NeoplasmsMedizinSingle-nucleotide polymorphismGenome-wide association studyBiologyAdenocarcinomaPolymorphism Single NucleotideReceptor IGF Type 103 medical and health sciencesBarrett Esophagus0302 clinical medicineRisk FactorsSomatomedinsInternal medicineGenetic variationmedicineBiomarkers TumorSNPHumansGenetic Predisposition to DiseaseRisk factorGerm-Line MutationCancer Biomarkers and Molecular EpidemiologyInsulin-like growth factor 1 receptorGenetic associationAgedGeneral MedicineMiddle Agedmedicine.diseaseRenal disorders Radboud Institute for Molecular Life Sciences [Radboudumc 11]030104 developmental biology030220 oncology & carcinogenesisBarrett's esophagusFemaleHuman medicineCarrier ProteinsGenome-Wide Association StudySignal TransductionCarcinogenesis
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Evidence for PTGER4 ,PSCA, and MBOAT7 as risk genes for gastric cancer on the genome and transcriptome level

2018

Genetic associations between variants on chromosome 5p13 and 8q24 and gastric cancer (GC) have been previously reported in the Asian population. We aimed to replicate these findings and to characterize the associations at the genome and transcriptome level. We performed a fine-mapping association study in 1926 GC patients and 2012 controls of European descent using high dense SNP marker sets on both chromosomal regions. Next, we performed expression quantitative trait locus (eQTL) analyses using gastric transcriptome data from 143 individuals focusing on the GC associated variants. On chromosome 5p13 the strongest association was observed at rs6872282 (P = 2.53 x 10(-04)) and on chromosome …

Male0301 basic medicineCancer ResearchGenotypeQuantitative Trait LocieQTL studyBiologyGPI-Linked ProteinsPolymorphism Single NucleotideGenomeTranscriptome03 medical and health sciencesAntigens NeoplasmStomach NeoplasmsGene expressionmedicineHumansSNPGenetic Predisposition to DiseaseRadiology Nuclear Medicine and imagingGeneGenetic Association StudiesOriginal ResearchCancer BiologyGeneticsGene Expression ProfilingChromosome MappingMembrane ProteinsChromosomeCancermedicine.diseaseNeoplasm ProteinsGene Expression Regulation Neoplastic030104 developmental biologyOncologygenetic association studyCase-Control StudiesExpression quantitative trait locigene expressionChromosomes Human Pair 5FemaleReceptors Prostaglandin E EP4 SubtypeAcyltransferasesChromosomes Human Pair 8Cancer Medicine
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ISL1 is a major susceptibility gene for classic bladder exstrophy and a regulator of urinary tract development

2017

AbstractPreviously genome-wide association methods in patients with classic bladder exstrophy (CBE) found association with ISL1, a master control gene expressed in pericloacal mesenchyme. This study sought to further explore the genetics in a larger set of patients following-up on the most promising genomic regions previously reported. Genotypes of 12 markers obtained from 268 CBE patients of Australian, British, German Italian, Spanish and Swedish origin and 1,354 ethnically matched controls and from 92 CBE case-parent trios from North America were analysed. Only marker rs6874700 at the ISL1 locus showed association (p = 2.22 × 10−08). A meta-analysis of rs6874700 of our previous and prese…

0301 basic medicinemedicine.medical_specialtyPathologyMesenchymeUrinary systemOrganogenesisLIM-Homeodomain ProteinsLocus (genetics)030105 genetics & heredityBiologyPolymorphism Single Nucleotidebladder extrophyArticlePronephrosMesoderm03 medical and health sciencesMiceBEEC bladder extrophy urinary tract development ISL1GenotypemedicineAnimalsHumansProtein IsoformsGenetic Predisposition to DiseaseBEECUrinary TractGeneZebrafishGeneticsMultidisciplinaryBladder ExstrophyGene Expression Regulation DevelopmentalISL1medicine.diseaseEmbryo Mammalianurinary tract developmentBladder exstrophy030104 developmental biologymedicine.anatomical_structureReconstructive and regenerative medicine Radboud Institute for Molecular Life Sciences [Radboudumc 10]LarvaISL1Medical geneticsFemaleTranscription FactorsRare cancers Radboud Institute for Health Sciences [Radboudumc 9]Scientific Reports
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No Association Between Vitamin D Status and Risk of Barrett's Esophagus or Esophageal Adenocarcinoma: A Mendelian Randomization Study.

2019

Contains fulltext : 215282.pdf (Publisher’s version ) (Closed access) BACKGROUND & AIMS: Epidemiology studies of circulating concentrations of 25 hydroxy vitamin D (25(OH)D) and risk of esophageal adenocarcinoma (EAC) have produced conflicting results. We conducted a Mendelian randomization study to determine the associations between circulating concentrations of 25(OH)D and risks of EAC and its precursor, Barrett's esophagus (BE). METHODS: We conducted a Mendelian randomization study using a 2-sample (summary data) approach. Six single-nucleotide polymorphisms (SNPs; rs3755967, rs10741657, rs12785878, rs10745742, rs8018720, and rs17216707) associated with circulating concentrations of 25(O…

Malemedicine.medical_specialtyEsophageal NeoplasmsMedizinSingle-nucleotide polymorphismAdenocarcinomaGastroenterologyPolymorphism Single NucleotideRisk AssessmentArticleBarrett EsophagusRisk FactorsInternal medicineMendelian randomizationEpidemiologymedicineVitamin D and neurologyBiomarkers TumorSNPHumansVitamin DHepatologybusiness.industryGastroenterologyOdds ratioDNA NeoplasmEsophageal cancerMendelian Randomization Analysismedicine.diseaseEuropeRenal disorders Radboud Institute for Molecular Life Sciences [Radboudumc 11]Barrett's esophagusNorth AmericaFemaleMorbiditybusinessClinical gastroenterology and hepatology : the official clinical practice journal of the American Gastroenterological Association
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The HLA-DQβ1 insertion is a strong achalasia risk factor and displays a geospatial north-south gradient among Europeans.

2016

Idiopathic achalasia is a severe motility disorder of the esophagus and is characterized by a failure of the lower esophageal sphincter to relax due to a loss of neurons in the myenteric plexus. Most recently, we identified an eight-amino-acid insertion in the cytoplasmic tail of HLA-DQβ1 as strong achalasia risk factor in a sample set from Central Europe, Italy and Spain. Here, we tested whether the HLA-DQβ1 insertion also confers achalasia risk in the Polish and Swedish population. We could replicate the initial findings and the insertion shows strong achalasia association in both samples (Poland P=1.84 × 10(-04), Sweden P=7.44 × 10(-05)). Combining all five European data sets - Central E…

0301 basic medicineMaleEuropean Continental Ancestry GroupShort ReportAchalasiaHuman leukocyte antigenWhite People03 medical and health sciences0302 clinical medicineSwedish populationGeneticGenetics esophageal achalasiaMutation RateGeneticsmedicineotorhinolaryngologic diseasesPrevalenceHLA-DQ beta-ChainsHumansIn patientEsophagusRisk factorGenetics (clinical)GeneticsHLA-DQ beta-ChainPolymorphism Geneticbusiness.industryEuropean populationmedicine.diseaseEsophageal AchalasiaEuropeMutagenesis Insertional030104 developmental biologymedicine.anatomical_structureAttributable risk030211 gastroenterology & hepatologyFemalebusinessHumanDemography
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Identification of loci of functional relevance to Barrett's esophagus and esophageal adenocarcinoma: Cross-referencing of expression quantitative tra…

2019

Esophageal adenocarcinoma (EA) and its precancerous condition Barrett's esophagus (BE) are multifactorial diseases with rising prevalence rates in Western populations. A recent meta-analysis of genome-wide association studies (GWAS) data identified 14 BE/EA risk loci located in non-coding genomic regions. Knowledge about the impact of non-coding variation on disease pathology is incomplete and needs further investigation. The aim of the present study was (i) to identify candidate genes of functional relevance to BE/EA at known risk loci and (ii) to find novel risk loci among the suggestively associated variants through the integration of expression quantitative trait loci (eQTL) and genetic…

0301 basic medicineCandidate geneEsophageal MucosaEsophageal NeoplasmsMedizinGene ExpressionGenome-wide association study0302 clinical medicineMathematical and Statistical TechniquesGeneticsMultidisciplinarySodium-Hydrogen Exchanger 3QStatisticsRGenomicsMetaanalysisGene Expression Regulation NeoplasticResearch Design030220 oncology & carcinogenesisPhysical SciencesMedicineResearch Articlemedicine.medical_specialtyScienceQuantitative Trait LociReplication StudiesContext (language use)BiologyAdenocarcinomaResearch and Analysis MethodsPolymorphism Single NucleotideMolecular Genetics03 medical and health sciencesBarrett EsophagusMolecular geneticsmedicineGeneticsGenome-Wide Association StudiesHumansGenetic Predisposition to DiseaseGene RegulationStatistical MethodsGeneMolecular BiologyGenetic associationProteinsBiology and Life SciencesComputational BiologyHuman Geneticsmedicine.diseaseGenome AnalysisRepressor Proteins030104 developmental biologyGenetic LociBarrett's esophagusExpression quantitative trait lociGenetics of DiseaseMathematicsGenome-Wide Association StudyPloS one
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Systematic screening for mutations in the human serotonin 1F receptor gene in patients with bipolar affective disorder and schizophrenia

1996

Using single strand conformational analysis we screened the complete coding sequence of the serotonin 1F (5-HT{sub 1F}) receptor gene for the presence of DNA sequence variation in a sample of 137 unrelated individuals including 45 schizophrenic patients, 46 bipolar patients, as well as 46 healthy controls. We detected only three rare sequence variants which are characterized by single base pair substitutions, namely a silent T{r_arrow}A transversion in the third position of codon 261 (encoding isoleucine), a silent C{r_arrow}T transition in the third position of codon 176 (encoding histidine), and a C{r_arrow}T transition in position -78 upstream from the start codon. The lack of significan…

GeneticsMutationCandidate geneStart codonmedicineCoding regionBiologyGene mutationTransversionmedicine.disease_causeGeneGenetics (clinical)Sequence (medicine)American Journal of Medical Genetics
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Systematic screening for mutations in the human serotonin-2A (5-HT2A) receptor gene: Identification of two naturally occurring receptor variants and …

1996

A statistically significant association between a silent mutation (102T/C) in the serotonin-2A (5-HT2A) receptor gene and schizophrenia has recently been reported in a sample of Japanese patients and healthy controls. This finding suggests that genetic predisposition to schizophrenia may be affected by a functional 5-HT2A receptor variant that is in linkage disequilibrium with 102T/C. In the present study, we have sought to identify genetic variation in the 5-HT2A receptor gene by screening genomic DNA samples from 91 unrelated subjects comprising 45 patients with schizophrenia and 46 healthy controls by using single-strand conformation analysis. We have identified four nucleotide sequence …

Silent mutationLinkage disequilibriumMolecular Sequence DataRestriction MappingBiologymedicine.disease_causePolymerase Chain ReactionReference ValuesGenetic variationConfidence IntervalsGeneticsGenetic predispositionmedicineHumansPoint MutationReceptor Serotonin 5-HT2AAmino Acid SequenceAlleleAllele frequencyAllelesGenetics (clinical)DNA PrimersGenetic associationGeneticsMutationPolymorphism GeneticBase SequenceChromosomes Human Pair 13Chromosome MappingGenetic VariationExonsReceptors SerotoninSchizophreniaHuman Genetics
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