Language deficits in specific language impairment, attention deficit/hyperactivity disorder, and autism spectrum disorder: An analysis of polygenic risk.
Genes that cause SLI-language problems do not cause language problems in ASD or ADHD, so do not treat these delays as the same beast.
01Research in Context
What this study did
Nudel et al. (2020) asked a simple question. Do the same genes that cause specific language impairment (SLI) also cause language problems in autism and ADHD?
They built a genetic risk score from thousands of SLI cases. Then they tested if that score predicted language scores in kids with ASD, ADHD, or SLI.
The sample came from two big UK cohorts. All children had full genetic and language testing.
What they found
The SLI risk score only predicted language trouble in kids who already had SLI. It did nothing for kids with ASD or ADHD.
In plain words, the genes that hurt language in SLI are different from the genes that hurt language in ASD or ADHD.
How this fits with other research
Vugs et al. (2014) and Kalliontzi et al. (2022) show that SLI kids also have weak working memory and executive function. Ron’s team did not test those skills, so the genetic story may be different for memory than for language.
Blanchette et al. (2016) found that Greek kids with SLI have wider language deficits than kids with dyslexia. Ron’s finding supports that view: SLI has its own genetic signature, so its profile should look unique.
Fullana et al. (2007) reported one teen with tiny Down-syndrome mosaicism who had only SLI. That single case hinted SLI can sit alone. Ron’s large-scale data now prove the hint: language impairment can be genetically separate from other disorders.
Why it matters
If you assess a child with language delay, do not assume the cause is the same across diagnoses. A kid with ASD and language problems may need different targets than a kid with pure SLI. Use full language batteries, not just autism checklists, and keep an eye on emerging genetic reports that may shape future precision plans.
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02At a glance
03Original abstract
Language is one of the cognitive domains often impaired across many neurodevelopmental disorders. While for some disorders the linguistic deficit is the primary impairment (e.g., specific language impairment, SLI), for others it may accompany broader behavioral problems (e.g., autism). The precise nature of this phenotypic overlap has been the subject of debate. Moreover, several studies have found genetic overlaps across neurodevelopmental disorders. This raises the question of whether these genetic overlaps may correlate with phenotypic overlaps and, if so, in what manner. Here, we apply a genome-wide approach to the study of the linguistic deficit in SLI, autism spectrum disorder (ASD), and attention deficit/hyperactivity disorder (ADHD). Using a discovery genome-wide association study of SLI, we generate polygenic risk scores (PRS) in an independent sample which includes children with language impairment, SLI, ASD or ADHD and age-matched controls and perform regression analyses across groups. The SLI-trained PRS significantly predicted risk in the SLI case-control group (adjusted R2 = 6.24%; P = 0.024) but not in the ASD or ADHD case-control groups (adjusted R2 = 0.0004%, 0.01%; P = 0.984, 0.889, respectively) nor for height, used as a negative control (R2 = 0.2%; P = 0.452). Additionally, there was a significant difference in the normalized PRS between children with SLI and children with ASD (common language effect size = 0.66; P = 0.044). Our study suggests no additive common-variant genetic overlap between SLI and ASD and ADHD. This is discussed in the context of phenotypic studies of SLI and related disorders. Autism Res 2020, 13: 369-381. © 2019 The Authors. Autism Research published by International Society for Autism Research published by Wiley Periodicals, Inc. LAY SUMMARY: Language deficits are characteristic of specific language impairment (SLI), but may also be found in other neurodevelopmental disorders, such as autism spectrum disorder (ASD) and attention deficit/hyperactivity disorder (ADHD). Many studies examined the overlaps and differences across the language deficits in these disorders, but few studies have examined the genetic aspect thereof. In this study, we use a genome-wide approach to evaluate whether common genetic variants increasing risk of SLI may also be associated with ASD and ADHD in the same manner. Our results suggest that this is not the case, and we discuss this finding in the context of theories concerning the etiologies of these disorders.
Autism research : official journal of the International Society for Autism Research, 2020 · doi:10.1016/j.ejphar.2013.07.016