Etiologies underlying sex differences in Autism Spectrum Disorders.
The male predominance of Autism Spectrum Disorders (ASD) is one of the best-known, and at the same time, one of the least understood characteristics of these disorders. In this paper we review genetic, epigenetic, hormonal, and environmental mechanisms underlying this male preponderance. Sex-specific effects of Y-linked genes (including SRY expression leading to testicular development), balanced and skewed X-inactivation, genes that escape X-inactivation, parent-of-origin allelic imprinting, and the hypothetical heterochromatin sink are reviewed. These mechanisms likely contribute to etiology, instead of being simply causative to ASD. Environments, both internal and external, also play important roles in ASD's etiology. Early exposure to androgenic hormones and early maternal immune activation comprise environmental factors affecting sex-specific susceptibility to ASD. The gene-environment interactions underlying ASD, suggested here, implicate early prenatal stress as being especially detrimental to boys with a vulnerable genotype.
Laboratory of Neurobiology and Behavior, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA. Electronic address: Sschaafsma@rockefeller.edu.
Sara M
SM
Schaafsma
Laboratory of Neurobiology and Behavior, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA.
Donald W
DW
Pfaff
D000818:Animals; D001519:Behavior / Q000502:physiology*; D002659:Child Development Disorders, Pervasive / Q000235:genetics*; D059647:Gene-Environment Interaction; D018392:Genomic Imprinting / Q000235:genetics*; D012739:Gonadal Steroid Hormones / Q000378:metabolism*; D006801:Humans; D012727:Sex Characteristics
D012739:Gonadal Steroid Hormones
Autism Spectrum Disorder; Gene–environment interaction; Genomic imprinting; Increased male incidence; Maternal immune activation; Prenatal stress; Sex chromosome; Sex differences; Testosterone; X-inactivation