Identification of common genetic risk variants for autism spectrum disorder
Grove J, Ripke S, Als TD, et al. Identification of common genetic risk variants for autism spectrum disorder. Nat Genet. 2019;51(3):431-444. https://doi.org/10.1038/s41588-019-0344-8.
Autism spectrum disorder (ASD) is a highly heritable and heterogeneous group of neurodevelopmental phenotypes diagnosed in more than 1% of children. Common genetic variants contribute substantially to ASD susceptibility, but to date no individual variants have been robustly associated with ASD. With a marked sample-size increase from a unique Danish population resource, we report a genome-wide association meta-analysis of 18,381 individuals with ASD and 27,969 controls that identified five genome-wide-significant loci. Leveraging GWAS results from three phenotypes with significantly overlapping genetic architectures (schizophrenia, major depression, and educational attainment), we identified seven additional loci shared with other traits at equally strict significance levels. Dissecting the polygenic architecture, we found both quantitative and qualitative polygenic heterogeneity across ASD subtypes. These results highlight biological insights, particularly relating to neuronal function and corticogenesis, and establish that GWAS performed at scale will be much more productive in the near term in ASD.
Autistic Traits and Suicidal Thoughts, Plans, and Self-Harm in Late Adolescence: Population-Based Cohort Study
Culpin I, Mars B, Pearson RM, et al. Autistic traits and suicidal thoughts, plans, and self-harm in late adolescence: Population-based cohort study. Journal of the American Academy of Child & Adolescent Psychiatry. 2018;57(5):320.e6. http://dx.doi.org/10.1016/j.jaac.2018.01.023.
To examine the hypothesis that autism spectrum disorders (ASD) diagnosis and traits in childhood are associated with suicidal thoughts, plans and self-harm at 16 years, and that any observed associations are explained by depression at 12 years.
We examined associations between ASD diagnosis and 4 dichotomized ASD traits (social communication, pragmatic language, repetitive behavior, and sociability) with suicidal and nonsuicidal self-harm, suicidal thoughts, and suicidal plans at age 16 years in 5,031 members of the United Kingdom−based birth cohort study the Avon Longitudinal Study of Parents and Children. We assessed whether any associations were explained by depressive symptoms in early adolescence measured by the Short Moods and Feelings Questionnaire at 12 years.
Children with impaired social communication had a higher risk of self-harm with suicidal intent (relative risk [RR] = 2.14, 95% CI = 1.28–3.58), suicidal thoughts (RR = 1.42, 95% CI = 1.06–1.91), and suicidal plans (RR = 1.95, 95% CI = 1.09–3.47) by age 16 years as compared to those without. There was no evidence for an association between ASD diagnosis and outcomes, although these analyses were imprecise because of small numbers. There was also no evidence of an association between other autism traits and the outcomes. Approximately 32% of the total estimated association between social communication impairment and self-harm was explained by depressive symptoms at 12 years.
Social communication impairments are an important autistic trait in relation to suicidality. Early identification and management of depression may be a preventative mechanism, and future research identifying other potentially modifiable mechanisms may lead to interventions against suicidal behavior in this high-risk group.
Nutritional and Dietary Interventions for Autism Spectrum Disorder: A Systematic Review
Sathe N, Andrews JC, McPheeters ML, Warren ZE. Nutritional and dietary interventions for autism spectrum disorder: A systematic review. Pediatrics. 2017. doi: 10.1542/peds.2017-0346
CONTEXT: Children with autism spectrum disorder (ASD) frequently use special diets or receive nutritional supplements to treat ASD symptoms.
OBJECTIVES: Our objective was to evaluate the effectiveness and safety of dietary interventions or nutritional supplements in ASD.
DATA SOURCES: Databases, including Medline and PsycINFO.
STUDY SELECTION: Two investigators independently screened studies against predetermined criteria.
DATA EXTRACTION: One investigator extracted data with review by a second investigator. Investigators independently assessed the risk of bias and strength of evidence (SOE) (ie, confidence in the estimate of effects).
RESULTS: Nineteen randomized controlled trials (RCTs), 4 with a low risk of bias, evaluated supplements or variations of the gluten/casein-free diet and other dietary approaches. Populations, interventions, and outcomes varied. Ω-3 supplementation did not affect challenging behaviors and was associated with minimal harms (low SOE). Two RCTs of different digestive enzymes reported mixed effects on symptom severity (insufficient SOE). Studies of other supplements (methyl B12, levocarnitine) reported some improvements in symptom severity (insufficient SOE). Studies evaluating gluten/casein-free diets reported some parent-rated improvements in communication and challenging behaviors; however, data were inadequate to make conclusions about the body of evidence (insufficient SOE). Studies of gluten- or casein-containing challenge foods reported no effects on behavior or gastrointestinal symptoms with challenge foods (insufficient SOE); 1 RCT reported no effects of camel’s milk on ASD severity (insufficient SOE). Harms were disparate.
LIMITATIONS: Studies were small and short-term, and there were few fully categorized populations or concomitant interventions.
CONCLUSIONS: There is little evidence to support the use of nutritional supplements or dietary therapies for children with ASD.