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Language in autism is heterogeneous, with a significant proportion of individuals having structural language difficulties and inclusion of language impairment as a specifier under Diagnostic and Statistical Manual of Mental Disorders (5th ed.) criteria for autism. This systematic review asked: What are the reporting patterns of variables pertaining to structural language in autism prior to and after publication of the Diagnostic and Statistical Manual of Mental Disorders (5th ed.)? What norm-referenced assessments does research use to characterize the language abilities of autistic individuals with respect to language impairment? This preregistered review (PROSPERO: CRD42021260394) followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Searches took place in September 2022 and included Linguistics and Language Behavior Abstracts, PsycINFO, PubMed, and the Directory of Open Access Journals. Search terms included three essential concepts: autism, language, and age. Two coders independently screened and evaluated articles. Searches yielded 57 qualifying studies, with mostly consistent reporting practices prior to and after the Diagnostic and Statistical Manual of Mental Disorders (5th ed.). Studies varied in how they defined language groups and in what norm-referenced measures they used. Interpreting research on structural language in autism requires attention to diagnostic and grouping criteria. Although inconsistency in reporting in original studies limited this review, better understanding the available information on structural language in autistic individuals aged 3–21 years may support identification of language needs. Lay abstractUnder the Diagnostic and Statistical Manual of Mental Disorders (5th ed.), language impairment can co-occur with autism. It is not yet clear how research defines, reports, and characterizes structural language abilities of autistic individuals eligible for school-based special education services (aged 3–21 years) in the United States. In the United States, students typically must be formally diagnosed to be eligible for services and supports. However, the quality of diagnosis is only as good as the research evidence on which diagnosis depends. To evaluate evidence quality, we examined how studies of school-aged autistic individuals report assessments of language ability. This systematic review included 57 studies using English language age-referenced assessments used to measure structural language. Findings showed many differences across studies in how language abilities were measured and reported. Also, none of the studies fully reported the variables relevant to characterizing language impairment. Outcomes were similar across versions of the Diagnostic and Statistical Manual of Mental Disorders. Findings indicate that researchers and clinicians should pay attention to reporting diagnostic and grouping criteria. Carefully interpreting research evidence is critical for ensuring that diagnostic criteria and supports are representative of and accessible to autistic individuals and relevant parties. 

Individuals with specific language impairment (SLI) struggle with language acquisition despite average non-verbal intelligence and otherwise typical development. One SLI account focuses on grammar acquisition delay. The current study aimed to detect novel rare genetic variants associated with performance on a grammar assessment, the Test of Early Grammatical Impairment (TEGI), in English-speaking children. The TEGI was selected due to its sensitivity and specificity, consistently high heritability estimates, and its absence from all but one molecular genetic study. We performed whole exome sequencing (WES) in eight families with SLI (n = 74 total) and follow-up Sanger sequencing in additional unrelated probands (n = 146). We prioritized rare exonic variants shared by individuals with low TEGI performance (n = 34) from at least two families under two filtering workflows: (1) novel and (2) previously reported candidate genes. Candidate variants were observed on six new genes (PDHA2, PCDHB3, FURIN, NOL6, IQGAP3, and BAHCC1), and two genes previously reported for overall language ability (GLI3 and FLNB). We specifically suggest PCDHB3, a protocadherin gene, and NOL6 are critical for ribosome synthesis, as they are important targets of SLI investigation. The proposed SLI candidate genes associated with TEGI performance emphasize the utility of precise phenotyping and family-based genetic study.