title: Brief report: aggression and stereotypic behavior in males with fragile X syndrome--moderating secondary genes in a "single gene" disorder.
abstract: Although fragile X syndrome (FXS) is a single gene disorder with a well-described phenotype, it is not known why some individuals develop more significant maladaptive behaviors such as aggression or autistic symptoms. Here, we studied two candidate genes known to affect mood and aggression, the serotonin transporter (5-HTTLPR) and monoamine oxidase A (MAOA-VNTR) polymorphisms, in 50 males with FXS ages 8-24 years. Mothers and fathers of participants reported the frequency and severity of aggressive/destructive, self-injurious, and stereotypic behaviors. Polymorphism genotypes were unrelated to age and IQ. Results showed a significant effect of 5-HTTLPR genotype on aggressive/destructive and stereotypic behavior; males with FXS who were homozygous for the high-transcribing long (L/L) genotype had the most aggressive and destructive behavior, and individuals homozygous for the short (S/S) genotype had the least aggression. Those with the L/L genotype also had the highest levels of stereotypic behavior. There was no effect of MAOA-VNTR on behavior; however those with the high-activity, 4-repeat genotype were more likely to be taking SSRI or SNRI medication. This preliminary study prompts consideration of secondary genes that may modify behavioral phenotype expression in neurodevelopmental disorders, even those with a single gene etiology such as FXS.
authors.affiliation: Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California-Davis, Medical Center, 2825 50th Street, Sacramento, CA 95817, USA. david.hessl@ucdmc.ucdavis.edu
authors.forename: David
authors.initials: D
authors.lastname: Hessl
authors.forename: Flora
authors.initials: F
authors.lastname: Tassone
authors.forename: Lisa
authors.initials: L
authors.lastname: Cordeiro
authors.forename: Kami
authors.initials: K
authors.lastname: Koldewyn
authors.forename: Carolyn
authors.initials: C
authors.lastname: McCormick
authors.forename: Cherie
authors.initials: C
authors.lastname: Green
authors.forename: Jacob
authors.initials: J
authors.lastname: Wegelin
authors.forename: Jennifer
authors.initials: J
authors.lastname: Yuhas
authors.forename: Randi J
authors.initials: RJ
authors.lastname: Hagerman
mesh_terms: D000293:Adolescent; D000328:Adult; D000374:Aggression / Q000523:psychology*; D002648:Child; D051860:Fragile X Messenger Ribonucleoprotein 1 / Q000235:genetics*; D005600:Fragile X Syndrome / Q000150:complications / Q000235:genetics* / Q000523:psychology*; D015870:Gene Expression / Q000235:genetics*; D005838:Genotype; D006801:Humans; D008297:Male; D018598:Minisatellite Repeats / Q000235:genetics; D008995:Monoamine Oxidase / Q000235:genetics; D011110:Polymorphism, Genetic / Q000235:genetics; D016728:Self-Injurious Behavior / Q000150:complications / Q000235:genetics / Q000523:psychology; D050486:Serotonin Plasma Membrane Transport Proteins / Q000235:genetics; D013239:Stereotyped Behavior; D011795:Surveys and Questionnaires
chemical_list: D051860:Fragile X Messenger Ribonucleoprotein 1; D008995:Monoamine Oxidase; D050486:Serotonin Plasma Membrane Transport Proteins; C497683:FMR1 protein, human; C493230:SLC6A4 protein, human