More than words: The 22q11.2 deletion syndrome as a genetic model for understanding variability in neuropsychiatric symptoms of children with Developmental Language Disorder

Developmental Language Disorder (DLD) is a neurodevelopmental disorder affecting approximately 3-7% of children in the general population. In addition to persistent language difficulties, many children with DLD experience symptoms of various neuropsychiatric disorders. However, the relationship between neuropsychiatric symptoms and language difficulties in DLD is insufficiently clear. A better understanding of this relationship, might improve our ability to identify those children with DLD who are most likely to develop neuropsychiatric symptoms and therefore potentially benefit from targeted intervention. The exact cause of DLD remains unknown and varies from child-to-child. Consequently, the relationship between language difficulties and neuropsychiatric symptoms is likely to vary among children with DLD as well. This variability might have prevented previous research to uncover this relationship in the group of children with DLD. Therefore, studying a population of children who all share the same genetic origin could provide an opportunity to identify relationships between language difficulties neuropsychiatric symptoms. This was the approach central to this dissertation. Children with DLD were compared to a group of children with a genetic condition: children with the 22q11.2 deletion syndrome (22q11DS). Similar to DLD, 22q11DS is associated with language difficulties and neuropsychiatric symptoms. However, these difficulties in 22q11DS have a shared cause, consisting of missing a small part of chromosome 22. Results of this dissertation provide new insights on the impact of language difficulties on the occurrence of neuropsychiatric symptoms in 22q11DS. The findings provide leads for future research and clinical care for children with 22q11DS and children with DLD.