Clinical Characteristics and Genetic Etiology of Children With Developmental Language Disorder

Whole exome sequencing and polygenic assessment of a Swedish cohort with severe developmental language disorder

Developmental language disorder (DLD) overlaps clinically, genetically, and pathologically with other neurodevelopmental disorders (NDD), corroborating the concept of the NDD continuum. There is a lack of studies to understand the whole genetic spectrum in individuals with DLD. Previously, we recruited 61 probands with severe DLD from 59 families and examined 59 of them and their families using microarray genotyping with a 6.8% diagnostic yield. Herein, we investigated 53 of those probands using whole exome sequencing (WES). Additionally, we used polygenic risk scores (PRS) to understand the within family enrichment of neurodevelopmental difficulties and examine the associations between the results of language-related tests in the probands and language-related PRS. We identified clinically significant variants in four probands, resulting in a 7.5% (4/53) molecular diagnostic yield. Those variants were in PAK2, MED13, PLCB4, and TNRC6B. We also prioritized additional variants for future studies for their role in DLD, including high-impact variants in PARD3 and DIP2C. PRS did not explain the aggregation of neurodevelopmental difficulties in these families. We did not detect significant associations between the language-related tests and language-related PRS. Our results support using WES as the first-tier genetic test for DLD as it can identify monogenic DLD forms. Large-scale sequencing studies for DLD are needed to identify new genes and investigate the polygenic contribution to the condition.

Genetic outcomes in children with developmental language disorder: a systematic review

Introduction

Developmental language disorder (DLD) is a common childhood condition negatively influencing communication and psychosocial development. An increasing number of pathogenic variants or chromosomal anomalies possibly related to DLD have been identified. To provide a base for accurate clinical genetic diagnostic work-up for DLD patients, understanding the specific genetic background is crucial. This study aims to give a systematic literature overview of pathogenic variants or chromosomal anomalies causative for DLD in children.

Methods

We conducted a systematic search in PubMed and Embase on available literature related to the genetic background of diagnosed DLD in children. Included papers were critically appraised before data extraction. An additional search in OMIM was performed to see if the described DLD genes are associated with a broader clinical spectrum.

Results

The search resulted in 15,842 papers. After assessing eligibility, 47 studies remained, of which 25 studies related to sex chromosome aneuploidies and 15 papers concerned other chromosomal anomalies (SCAs) and/or Copy Number Variants (CNVs), including del15q13.1-13.3 and del16p11.2. The remaining 7 studies displayed a variety of gene variants. 45 (candidate) genes related to language development, including FOXP2, GRIN2A, ERC1, and ATP2C2. After an additional search in the OMIM database, 22 of these genes were associated with a genetic disorder with a broader clinical spectrum, including intellectual disability, epilepsy, and/or autism.

Conclusion

Our study illustrates that DLD can be related to SCAs and specific CNV's. The reported (candidate) genes (n = 45) in the latter category reflect the genetic heterogeneity and support DLD without any comorbidities and syndromic language disorder have an overlapping genetic etiology.

Nonverbal Executive Functioning in Relation to Vocabulary and Morphosyntax in Preschool Children With and Without Developmental Language Disorder

PURPOSE

Developmental language disorder (DLD) is characterized by persistent and unexplained difficulties in language development. Accumulating evidence shows that children with DLD also present with deficits in other cognitive domains, such as executive functioning (EF). There is an ongoing debate on whether exclusively verbal EF abilities are impaired in children with DLD or whether nonverbal EF is also impaired, and whether these EF impairments are related to their language difficulties. The aims of this study were to (a) compare nonverbal performance of preschoolers with DLD and typically developing (TD) peers, (b) examine how nonverbal EF and language abilities are related, and (c) investigate whether a diagnosis of DLD moderates the relationship between EF and language abilities.

METHOD

A total of 143 children (nDLD = 65, nTD = 78) participated. All children were between 3 and 6.5 years old and were monolingual Dutch. We assessed nonverbal EF with a visual selective attention task, a visuospatial short-term and working memory task, and a task gauging broad EF abilities. Vocabulary and morphosyntax were each measured with two standardized language tests. We created latent variables for EF, vocabulary, and morphosyntax.

RESULTS

Analyses showed that children with DLD were outperformed by their TD peers on all nonverbal EF tasks. Nonverbal EF abilities were related to morphosyntactic abilities in both groups, whereas a relationship between vocabulary and EF skills was found in the TD group only. These relationships were not significantly moderated by a diagnosis of DLD.

CONCLUSIONS

We found evidence for nonverbal EF impairments in preschool children with DLD. Moreover, nonverbal EF and morphosyntactic abilities were significantly related in these children. These findings may have implications for intervention and support the improvement of prognostic accuracy.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.24121287.

Behaviors related to autism spectrum disorder in children with developmental language disorder and children with 22q11.2 deletion syndrome

Background and Aim

Children with Developmental Language Disorder (DLD) are at an increased risk to develop behaviors associated with Autism Spectrum Disorder (ASD). The relationship between early language difficulties and the occurrence of ASD-related behaviors in DLD is poorly understood. One factor that may hinder progress in understanding this relationship is the etiological heterogeneity of DLD. We therefore study this relationship in an etiologically homogeneous group of children, who share phenotypic characteristics with children with DLD: children with the 22q11.2 Deletion Syndrome (22q11DS). We compare children with 22q11DS, to children with DLD and age-matched typically developing children (TD).

Method

44 children with 22q11DS, 65 children with DLD and 81 TD children, between 3.0-6.5 years old, participated in a longitudinal cohort study that included a baseline measure and a follow-up measure with a 1-year interval. A parental questionnaire (SRS-2) was used to measure the incidence of behaviors in two key behavioral domains associated with ASD: Social Communication and Interaction and Restricted Repetitive Behaviors and Interests. At baseline, we assessed children's expressive and receptive language abilities as well as their intellectual functioning with standardized tests. We compared the distribution of ASD-related behaviors between the three groups. We used regression analyses to investigate whether language abilities at baseline predict ASD-related behavior at follow-up, accounting for ASD-related behavior at baseline, demographic variables and intellectual functioning.

Results

Both the children with 22q11DS and the children with DLD displayed significantly more ASD-related behaviors than the TD children. Over 30% of children in both clinical groups had scores exceeding the subclinical threshold for ASD in both behavioral domains. Both in 22q11DS and DLD, baseline receptive language scores were negatively correlated with ASD-related behaviors 1 year later, when controlling for baseline SRS-scores. However, this association was statistically significant only in children with 22q11DS, even when controlled for IQ-scores, and it was significantly stronger as than in the TD group. The strength of the association did not differ significantly between 22q11DS and DLD.

Conclusion

Both children with 22q11DS and children with DLD present with elevated rates of ASD-related behaviors at a preschool-age. Only in children with 22q11DS we observed that weaker receptive language skills were related to increased behavioral problems in the domain of social communication and interaction one year later.

Implications

Our findings indicate that relations between early language impairment and other behavioral phenotypes may be more feasible to detect in a subgroup of children with a homogeneous etiology, than in a group of children with a heterogeneous etiology (such as children with DLD). Our results in 22q11DS reveal that receptive language is especially important in predicting the occurrence of ASD-related behaviors. Future research is needed to determine to what extent receptive language predicts the occurrence of ASD-related behaviors in children with DLD, especially among those children with DLD with the weakest receptive language. Clinically, screening for ASD-related behaviors in children with developmental language difficulties is recommended from a young age, especially among children with receptive language difficulties.

What happens in the brain?

A new imaging method reveals previously undetected structural differences that may contribute to developmental language disorder.