Language impairment in the 22q11.2 deletion syndrome

The 22q11.2 Deletion Syndrome (22q11DS) is relatively common genetic syndrome with large phenotypical variation. Symptoms include, but are not limited to: congenital heart diseases, cleft palate, velopharyngeal insufficiency, hypotonia, below average intelligence, and an increased risk to develop schizophrenia. Previous studies also show a range of cognitive impairments in domains such as visuo-spatial processing, executive functioning, and motor skills in these patients. Moreover, many individuals with 22q11DS display severe language delays in early childhood. Language problems in this group may have gone unnoticed due to the palatal problems and the on average lower intelligence and cognitive functioning. Interestingly, research thus far suggests that language delays are not related to intellectual disability. To date, detailed, linguistically informed descriptions of language development in 22q11DS are scarce, and mostly limited to elementary school-aged children. Moreover, little is known about possible connections of the language difficulties with observed underlying neurocognitive deficits or psychopathology in 22q11DS. Knowledge about these connections could enhance our understanding of language difficulties in other populations with language problems, such as children with Developmental Language Disorder (DLD).

To address this knowledge gap, the Netherlands Organization for Scientific Research (NWO) has provided funding for a large research program, including in-depth studies on (1) language development in 3- to 6-year-old children with 22q11DS, (2) neurocognitive mechanisms associated with language acquisition in this group of young children, and (3) the language skills of adolescents with 22q11DS and their possible relation to the expression of schizophrenia and related psychotic disorders. Results will be compared with typically developing controls, children with a cleft palate without a syndromic origin and children with DLD, who experience language difficulties without a clear cause. Here we present the rationale, design and method of this unique, interdisciplinary program.

This research program has strong theoretical and clinical potential. Developmental language impairments have a profound impact on an individual’s life and are associated with academic failure, social disadvantage, and behavioral and psychiatric problems. It is thus vital to learn more about the cause(s) of language impairments. The results of this project can strengthen our knowledge of the mechanisms involved in (disordered) language acquisition. The innovative approach of leveraging the genetic homogeneity of 22q11DS can shed light on the complex pathway from genes via (neuro)cognition to language, and support tailored intervention programs for children with 22q11DS and DLD. Furthermore, a detailed picture of the developmental language trajectories in 22q11DS may contribute to better guidelines for speech-language therapists and support formulating prognoses. Finally, the program can be a stepping stone for investigations of the associations between early language development and mental health in later life.