title: Lessons learned--resolving the enigma of genetic factors in IBS.
abstract: IBS is the most prevalent functional gastrointestinal disorder and phenotypically characterized by chronic abdominal discomfort, pain and altered defecation patterns. The pathophysiology of IBS is multifactorial, albeit with a substantial genetic component. To date, studies using various methodologies, ranging from family and twin studies to candidate gene approaches and genome-wide association studies, have identified several genetic variants in the context of IBS. Yet, despite enlarged sample sizes, increased statistical power and meta-analyses in the past 7 years, positive associations are still scarce and/or have not been reproduced. In addition, epigenetic and pharmacogenetic approaches remain in their infancy. A major hurdle is the lack of large homogenized case-control cohorts recruited according to standardized and harmonized criteria. The COST Action BM1106 GENIEUR (GENes in Irritable Bowel Syndrome Research Network EURope) has been established to address these obstacles. In this Review, the (epi)genetic working group of GENIEUR reports on the current state-of-the-art in the field, highlights fundamental flaws and pitfalls in current IBS (epi)genetic research and provides a vision on how to address and improve (epi)genetic approaches in this complex disorder in the future.
authors.affiliation: Department of Basic Sciences, Laboratory of Biology, School of Medicine, University of Athens, Michalakopoulou 176, 11527 Athens, Greece.
authors.forename: Maria
authors.initials: M
authors.lastname: Gazouli
authors.affiliation: Translational Research Center for Gastrointestinal Disorders (TARGID), University Hospital Leuven, Herestraat 49, Leuven 3000, Belgium.
authors.forename: Mira M
authors.initials: MM
authors.lastname: Wouters
authors.affiliation: Institute for Genetic Engineering and Biotechnology, University of Sarajevo, Kemalbegova 10, 71.000 Sarajevo, Bosnia and Herzegovina.
authors.forename: Lejla
authors.initials: L
authors.lastname: Kapur-Pojskić
authors.affiliation: Vestfold Hospital Trust, Tønsberg, Department of Internal Medicine, Division of Gastroenterology, P.O. Box 2168, 3103 Tønsberg, Norway.
authors.forename: May-Bente
authors.initials: MB
authors.lastname: Bengtson
authors.affiliation: The Suzanne Levy Gertner Oncogenetics Unit, Chaim Sheba Medical Centre, 52621 Tel-Hashomer, Israel.
authors.forename: Eitan
authors.initials: E
authors.lastname: Friedman
authors.affiliation: Laboratory for Molecular Biomedicine, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Vojvode Stepe 444a, 23 11010 Belgrade, Serbia.
authors.forename: Gordana
authors.initials: G
authors.lastname: Nikčević
authors.affiliation: Department of Electron Microscopy / Molecular Pathology, The Cyprus Institute of Neurology and Genetics, P.O. Box 23462, 1683 Nicosia, Cyprus.
authors.forename: Christiana A
authors.initials: CA
authors.lastname: Demetriou
authors.affiliation: Department of Gastroenterology and Hepatology, Wroclaw Medical University, Borowska 213, 50-556 Wroclaw, Poland.
authors.forename: Agata
authors.initials: A
authors.lastname: Mulak
authors.affiliation: Neuro-immuno-gastroenterology Lab, Digestive Diseases Research Unit, Vall d'Hebron Institut de Recerca. Department of Gastroenterology, Hospital Universitari Vall d'Hebron &Facultat de Medicina, Universitat Autònoma de Barcelona and Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, Paseo Vall d'Hebron 119-129, 08035 Barcelona, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Santos
authors.affiliation: Institute of Human Genetics, Department of Human Molecular Genetics, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany.
authors.forename: Beate
authors.initials: B
authors.lastname: Niesler
mesh_terms: D057890:Epigenomics; D014644:Genetic Variation; D055106:Genome-Wide Association Study; D006801:Humans; D043183:Irritable Bowel Syndrome / Q000209:etiology / Q000235:genetics*; D008967:Molecular Biology; D009619:Nociceptors; D012107:Research Design; D012701:Serotonin / Q000378:metabolism; D019108:Tight Junctions / Q000502:physiology
chemical_list: D012701:Serotonin