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Pleiotropic Mechanisms Indicated for Sex Differences in Autism
Ileena Mitra1, Kathryn Tsang1, Christine Ladd-Acosta2
1Department of Psychiatry and Institute for Human Genetics, University of California, San Francisco, California, United States of America.
Plos Genetics
|November 16, 2016
Summary
Autism spectrum disorder (ASD) shows a male predominance. This study found sex-specific genetic factors on the X chromosome and links between physical traits and ASD risk, suggesting broader biological mechanisms.
Area of Science:
- Genetics
- Neurodevelopmental Disorders
- Human Biology
Background:
- Autism spectrum disorders (ASDs) exhibit significant sexual dimorphism, with a notable male preponderance.
- Existing hypotheses for this dimorphism include genetic load, X-chromosome effects, hormonal influences, sex-differential gene expression, and shared mechanisms with secondary sex characteristics.
Purpose of the Study:
- To investigate the genetic underpinnings of sex differences in autism spectrum disorders.
- To test specific genetic hypotheses, including X-chromosome contribution and pleiotropy with traits related to sexual dimorphism.
Main Methods:
- Analysis of a large single nucleotide polymorphism (SNP) dataset to identify sex-specific genome-wide significant loci.
- Examination of genetic hypotheses related to sex differences in ASD risk.
Main Results:
- Identification of distinct, sex-specific genome-wide significant loci associated with ASD.
- No evidence supporting a higher genetic risk load in females.
- Evidence for sex heterogeneity on the X chromosome and the contribution of sex-heterogeneous SNPs for anthropometric traits to ASD risk.
Conclusions:
- The findings support a biological basis for sex differences in ASDs, implicating pleiotropy between the determination of secondary sex characteristics and ASD risk.
- These results suggest that mechanisms beyond the brain contribute to the observed sexual dimorphism in autism spectrum disorders.
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