title: The role of rs2237781 within GRM8 in eating behavior.
abstract: BACKGROUND
  The glutamate receptor, metabotropic 8 gene (GRM8) encodes a G-protein-coupled glutamate receptor and has been associated with smoking behavior and liability to alcoholism implying a role in addiction vulnerability. Data from animal studies suggest that GRM8 may be involved in the regulation of the neuropeptide Y and melanocortin pathways and might influence food intake and metabolism. This study aimed to investigate the effects of the genetic variant rs2237781 within GRM8 on human eating behavior.
  
  
  METHODS
  The initial analysis included 548 Sorbs from Germany who have been extensively phenotyped for metabolic traits and who completed the German version of the three-factor eating questionnaire. In addition, we analyzed two independent sample sets comprising 293 subjects from another German cohort and 430 Old Order Amish individuals. Genetic associations with restraint, disinhibition, and hunger were assessed in an additive linear regression model.
  
  
  RESULTS
  Among the Sorbs the major G allele of rs2237781 was significantly associated with increased restraint scores in eating behavior (P = 1.9 × 10(-4); β = +1.936). The German cohort and the Old Order Amish population revealed a trend in the same direction for restraint (P = 0.242; β = +0.874; P = 0.908; β = +0.096; respectively). A meta-analysis resulted in a combined P = 3.1 × 10(-3) (Z-score 2.948).
  
  
  CONCLUSIONS
  Our data suggest that rs2237781 within GRM8 may influence human eating behavior factors probably via pathways involved in addictive behavior.
authors.affiliation: Department of Medicine, University of Leipzig Leipzig, Germany.
authors.forename: Marie-Therese
authors.initials: MT
authors.lastname: Gast
authors.affiliation: Department of Medicine, University of Leipzig Leipzig, Germany.
authors.forename: Anke
authors.initials: A
authors.lastname: Tönjes
authors.affiliation: IFB Adiposity Diseases, University of Leipzig Leipzig, Germany.
authors.forename: Maria
authors.initials: M
authors.lastname: Keller
authors.affiliation: IFB Adiposity Diseases, University of Leipzig Leipzig, Germany ; Department for Neurology, Max-Planck-Institute for Human Cognitive and Brain Sciences Leipzig, Germany.
authors.forename: Annette
authors.initials: A
authors.lastname: Horstmann
authors.affiliation: Division of Endocrinology, Diabetes and Nutrition, University of Maryland School of Medicine Baltimore, Maryland ; Diabetes and Endocrinology Section, Veterans Administration Medical Center Baltimore, Maryland.
authors.forename: Nanette
authors.initials: N
authors.lastname: Steinle
authors.affiliation: Institute for Medical Informatics, Statistics and Epidemiology, University of Leipzig Leipzig, Germany ; LIFE Research Center, University of Leipzig Leipzig, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Scholz
authors.affiliation: IFB Adiposity Diseases, University of Leipzig Leipzig, Germany.
authors.forename: Ines
authors.initials: I
authors.lastname: Müller
authors.affiliation: Department for Neurology, Max-Planck-Institute for Human Cognitive and Brain Sciences Leipzig, Germany ; Clinic of Cognitive Neurology, University of Leipzig Leipzig, Germany.
authors.forename: Arno
authors.initials: A
authors.lastname: Villringer
authors.affiliation: Department of Medicine, University of Leipzig Leipzig, Germany ; IFB Adiposity Diseases, University of Leipzig Leipzig, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Stumvoll
authors.affiliation: IFB Adiposity Diseases, University of Leipzig Leipzig, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Kovacs
authors.affiliation: IFB Adiposity Diseases, University of Leipzig Leipzig, Germany.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Böttcher
keywords: Addiction; alcohol intake; food intake; human eating behavior; smoking behavior