Background Angelman syndrome (AS) is a rare, neurodevelopmental disorder which presents itself with severe cognitive and physical developmental delay. AS is characterized by frequent laughing and...Show moreBackground Angelman syndrome (AS) is a rare, neurodevelopmental disorder which presents itself with severe cognitive and physical developmental delay. AS is characterized by frequent laughing and smiling, but recent evidence suggests that individuals with AS, especially those with non-deletion genotypes, may experience high levels of anxiety. The aim of the current study was to examine the influence of genotype on anxiety and emotional/behavioral problems in general in Angelman syndrome (AS), and to test whether relationships between genotype and anxiety or emotional/behavioral problems were mediated by cognitive developmental level. Methods For this purpose, 79 children with AS were included from a Dutch clinical record study. The children were separated into two groups according to genotype, namely the deletion and non-deletion group (predictor). The Bayley Scales of Infant Development-III NL cognition subscale was used to measure cognitive developmental levels (mediator) and the Child Behavior Checklist (CBCL) was used to measure anxiety and emotional/behavioral problems in general (outcome). The study is cross-sectional in nature. A mediation analysis was performed, including four linear regression analyses. Results Genotype did not significantly predict anxiety levels (š¯›½ = .18, p = .117) or emotional/behavioral problems (š¯›½ = .06, p = .589). Genotype significantly predicted cognitive developmental level (š¯›½ = .63, p < .001), as children with a non-deletion had a higher cognitive developmental level than children with a deletion. Cognitive developmental level neither predicted anxiety (š¯›½ = .16, p = .155) nor emotional/behavioral problems in general significantly (š¯›½ = .07, p = .554). Genotype did not significantly predict anxiety (š¯›½ = .13, p = .387) or emotional/behavioral problems (š¯›½ = .05, p = .746) with cognitive developmental level taken into account. This indicates that cognitive developmental level does not mediate the relationship between genotype and anxiety or emotional/behavioral problems. Key conclusions In conclusion, the findings of the current study suggest that emotional/behavioral problems, and specifically anxiety, are not affected by genotype or cognitive developmental level in children with AS. Therefore, the mediation model was not found to be significant. These findings may be taken to indicate that attention should be given to children of both genotype subgroups in clinical practice.Show less
Het doel van het huidige onderzoek was het achterhalen van de onderliggende biologische processen rondom leesmotivatie en leesbegrip. Hierbij werd gekeken naar de invloed van dopamine en of deze...Show moreHet doel van het huidige onderzoek was het achterhalen van de onderliggende biologische processen rondom leesmotivatie en leesbegrip. Hierbij werd gekeken naar de invloed van dopamine en of deze invloed verschilde tussen mensen met het 7-repeat DRD4 genotype en mensen met het 4-repeat DRD4 genotype. Het is namelijk bekend dat dopamine betrokken is bij motivatie- en aandachtsprocessen. Daarnaast is bekend dat mensen met het 7-repeat DRD4 genotype een minder efficiĆ«nte dopamineproductie hebben, welke nodig is om aandacht vast te kunnen houden. Er was echter nog niet specifiek onderzoek gedaan naar de invloed van dopamine op leesmotivatie. Vandaar dat de volgende hoofdvraag centraal stond: "Wat is de invloed van dopamine op leesmotivatie en leesbegrip bij ervaren lezers?ā€¯. Hierbij werden twee modellen getoetst. Het eerste model ging uit van een direct effect van dopamine op leesmotivatie en leesbegrip. Het tweede model was een mediatiemodel waarbij leesmotivatie de mediator was tussen het DRD4-genotype en leesbegrip. Uit de analyses bleek het verschil in leesmotivatie en leesbegrip niet significant te zijn bij een hoger of lager dopaminegehalte. Daarnaast bleek er geen sprake te zijn van een mediatiemodel. Wel werd er een relatie gevonden tussen het DRD4-genotype en leesmotivatie, waarbij mensen met het 7- repeat allel minder invloed ondervonden van dopamine dan mensen met het 4-repeat allel. Dit was tegengesteld aan de verwachting. Vervolgonderzoek moet uitwijzen of dit effect kan worden gerepliceerd of dat dit effect toe te schrijven is aan de kleine sample.Show less
Research master thesis | Developmental Psychopathology in Education and Child Studies (research) (MSc)
open access
2016-01-01T00:00:00Z
Methylation of the serotonin transporter gene (5HTTLPR) might be one of the underlying molecular mechanisms of epigenetics through which effects of child maltreatment persist into adulthood. We...Show moreMethylation of the serotonin transporter gene (5HTTLPR) might be one of the underlying molecular mechanisms of epigenetics through which effects of child maltreatment persist into adulthood. We investigated how the experience of child maltreatment is associated with methylation density of 5HTTLPR and whether 5HTT genotype moderates this relation. The sample consisted of 22 females selected from the larger TwinPAD study (Out, Pieper, Bakermans-Kranenburg & Van IJzendoorn, 2010). DNA was obtained from buccal cells. The percentage of methylation in the first 245 bps was assessed using quantitative mass spectroscopy. Experiences of child maltreatment were established using the Adult Attachment Interview, coded with the Modified Maltreatment Classification System. We found that maltreatment severity was not significantly related to higher methylation density of 5HTTLPR, but the interaction of genotype with maltreatment severity significantly predicted methylation density. For carriers of the ss and sl genotype, more severe maltreatment was associated with higher methylation density, while for carriers of the ll genotype more severe maltreatment was associated with lower methylation density. We conclude that the relation between maltreatment severity and methylation density of 5HTTLPR is moderated by genotype, with ll carriers being protected against the methylating effects associated with maltreatment experiences. This study suggests that DNA methylation may be one of the molecular mechanism by which child maltreatment affects current and long-term functioning.Show less
