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| Neurogenetics and problem behavior in people with intellectual/developmental disabilities |
| Monday, May 25, 2009 |
| 9:00 AM–10:20 AM |
| North 128 |
| Area: DDA/AUT; Domain: Applied Behavior Analysis |
| Chair: Craig H. Kennedy (Vanderbilt University) |
| Discussant: Peter McGill (Tizard Centre, University of Kent) |
| Abstract: This symposium will focus on interactions between neurogenetics and problem behavior in people with intellectual/developmental disabilities. Neurogenetics focuses on the genetic regulation of neuronal and glial cells in the nervous system. Recent findings have shown that polymorphisms in promoter genes for enzymes that regulate cellular function can influence the expression of violent behavior in general population and schizophrenic samples. The goal of this symposium, chaired by Craig Kennedy, is to present recent findings on how genes interact with the problem behavior of people with intellectual/developmental disabilities (I/DD). In the first presentation by Paul Langthorne, gene x environment interactions are studied in relation to the expression of problem behavior in people with either Fragile-X or Smith-Magenis genetic syndromes. The next paper, presented by Michael May, is an association study between monoamine oxidase A promoter gene polymorphisms and the occurrence of problem behavior in adults with I/DD. The final paper, presented by Craig Kennedy, will look at gene x gene interactions for monoaminergic circuits and their associations with the problem behavior of adults with I/DD. Peter McGill will provide a discussion of these findings. |
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| Problem behavior in fragile X and Smith-Magenis syndromes: A preliminary experimental analysis of gene-environment interactions |
| PAUL D. LANGTHORNE (Tizard Centre), Peter McGill (Tizard Centre, University of Kent) |
| Abstract: There has been increased attention, in recent years, to the role of gene-environment interactions (GxE) in the development and maintenance of problem behaviour displayed by individuals with developmental disabilities. It has been suggested that genetic variables may influence the reinforcing value of some of the consequences commonly maintaining problem behavior. The current study examined this thesis by analysing the function of problem behavior displayed by children with fragile X and Smith-Magenis syndromes. Experimental functional analyses were conducted with 8 children with each diagnosis. These groups were selected as prior research suggested differences in the probability of individuals with these syndromes displaying attention-maintained problem behavior. Analysis of the data gathered will consider a) the extent to which the problem behaviour of participants was sensitive to environmental influence and b) the extent of between-group differences in the function served by problem behavior. |
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| A Functional Polymorphism in the Monoamine Oxidase A Gene is Associated with Problem Behavior in Adults with Intellectual/Developmental Disabilities |
| MICHAEL E. MAY (Southern Illinois University), Craig H. Kennedy (Vanderbilt University) |
| Abstract: A functional polymorphism in the promoter of the gene encoding monoamine oxidase A (MAOA; EC 1.4.3.4) has been associated with problem behavior in various general and clinical populations. In this study, the aim was to examine the association of MAOA alleles in adults with intellectual/developmental disabilities (I/DD) with established histories of problem behavior. DNA samples and behavioral records were obtained from adult males with I/DD, distinguished only by the presence or absence of problem behavior. These data were compared with a gender, ethnicity, and age-matched contrast sample. About 43% (15/35) of adults with I/DD and problem behavior possessed the short allele (3 repeats) version of the MAOA gene. In comparison, 20% (7/35) of adults with I/DD and no problem behavior and 20% (7/35) of the contrast group had the short-allele MAOA polymorphism. Therefore, a common variant in the MAOA gene may be associated with problem behavior in adults with I/DD. However, a better understanding of neurogenetic contributions to problem behavior may be required for a more complete understanding of the etiology of these behaviors. |
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| Serotonin Transporter Polymorphisms and Aggression in Adult Males with Intellectual/Developmental Disabilities |
| Michael E. May (Southern Illinois University), CRAIG H. KENNEDY (Vanderbilt University) |
| Abstract: The serotonin transporter (SERT) gene has been investigated for its association with specific behavioral phenotypes in various general and clinical populations. Although results of these investigations are equivocal, recent efforts suggest a link between the genes and problem behavior in subgroups of people with I/DD. The aim in this study was twofold. The first aim was to examine the association of the promoter region (5-HTTLPR) and a variable number tandem repeat in the second intron (STin2) in adult males with and without intellectual/developmental disabilities (I/DD) for an association. The second aim was to examine the association of the two SERT polymorphisms with problem behavior in people with I/DD compared to people without problem behavior. DNA samples and behavioral records were obtained from adult males with I/DD, distinguished only by the presence or absence of problem behavior. These data were compared with a matched contrast sample. No association was found between either SERT polymorphism and problem behavior. The failure to establish a single-gene association with problem behavior in the current study suggests there may be other candidate genes or interactions between genes that increase susceptibility to environmental contingencies occasioning problem behavior in people with I/DD. |
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