The gender distribution of autism spectrum disorder has raised flags for researchers for years. Males are 4 to 5 times more likely to be diagnosed with ASD than females. Recent studies approach the discrepancy through various lenses, propelling the dialogue on gender as a mediating factor for autism. The current diagnostic criteria for ASD were designed primarily from symptoms in boys, so if symptoms manifest differently in girls, then some girls may be slipping through the diagnostic cracks. Concurrently, we have a weaker understanding of girl’s symptoms because the discrepancy in incidence leaves most research populations with imbalanced gender distributions. Neuropsychiatries have informed this dialogue with the discovery that symptoms can be different in girls, which implies the need for varied treatment. This week, at the International Meeting for Autism Research in Spain, two new studies are slated to present results—prior to official publication—on the association between autism and gender.
One study,[i] conducted by Yale University researchers, examines the interaction between genetics, gender, and autism, hypothesizing that the extra X chromosome of females provides protection from genetic mutations associated with autism. The study assesses the gender distribution of rare variants in ASD probands, finding that female probands have more variants than males. The expression of these high-risk mutations in females with autism supports the hypothesis that the female extra X chromosome serves to protect women from autism spectrum disorders by suggesting that women who have autism have such because higher-risk mutations “overwhelmed” their “protective mechanism.”[ii] The mutations found are referred to as “de novo” mutations, which are epigenetic, changes occurring in the sperm or egg, as opposed to genetically transferrable.
The second study[iii] pertaining to gender discrepancies presented at IMFAR was designed to study the ‘Effects of a Targeted Face-Processing Intervention On Visual Attention to Naturalistic Social Scenes,’ but found that significantly different results contingent on gender, suggesting the need for varying treatment strategies, research studies, and ultimately diagnostic criteria. The study, conducted by the Marcus Autism Center of Emory University, assessed changes in processing abilities—such as identity recognition with changes in expression, viewpoint, features, face process strategies, and attention or ability to ascertain information from eyes—by using a computer-based intervention called Let’s Face It! (LFI!). Researchers concluded that after a concentrated intervention with LFI! children with ASD paid grater attention to faces and less to background regions. However, the chief of the division of autism and related disorders at Emory University School of Medicine asserts, that when the data was displayed by gender, “In boys, the more they looked at the eyes, the less socially disabled they are. In girls, the more they looked at the eyes, the more disabled they are… we have to take gender as a mediating factor.”
Both studies confirm speculation that autism spectrum disorders manifest diversely between genders, necessitating new approaches to treating females with ASD. Further, the study conducted by Yale University suggests that while incidence of autism for females is lower, the manifestation of autism may be of higher-risk. Finally, the protective mechanism occurring in females could offer insight regarding the development of autism spectrum disorder in general.
[i] Whole-Exome and CNV Data for ASD Sex Bias. S. J. Sanders* and M. W. State, Yale University School of Medicine
[ii] “Girls with Autism May Need Different Treatment | Health24.” Health24. N.p., 2 May 2013. Web. 03 May 2013. <http://www.health24.com/Parenting/Child/News/Girls-with-autism-may-need-different-treatment-20130502>.
[iii] Effects of a Targeted Face-Processing Intervention On Visual Attention to Naturalistic Social Scenes. P. Lewis*1, J. M. Moriuchi1, C. Klaiman1, J. Wolf2, L. Herlihy3, W. Jones1, A. Klin1, J. W. Tanaka4 and R. T. Schultz5, (1)Marcus Autism Center, Children’s Healthcare of Atlanta & Emory University School of Medicine, (2)Yale Child Study Center, (3)University of Connecticut, (4)University of Victoria, (5)Children’s Hospital of Philadelphia