sis of autism and fetal testosterone levels were positively correlated with autistic traits in general population. [1][2][3][4] In addition, females with conditions of abnormal prenatal exposure to testosterone and its sex steroid precursors, such as congenital adrenal hyperplasia and polycystic ovary syndrome, were found to have higher rate of autistic traits as well as their children were of higher risk of developing autism. 5,6 However, the exact mechanism by which these hormones influence the manifestation of autistic traits remains undiscovered. Another model explaining higher prevalence of ASD in males is a female protective model which suggests that multiple genetic factors contribute to the development of ASD and that higher threshold of genetic liability is required in females compared to males. 7 Zhang et al. 8 demonstrated genetic evidence of sex differences in ASD confirming female protective model, employing investigation of de novo mutations, common variants of ASD candidate genes and their co-expression in male and female brains. Genetic architecture of ASD involves rare and de novo variants that were identified in studies using whole genome or exome sequencing technologies as well as low-risk com-