Sex differences in
psychiatric disorders are common, which is particularly striking in
autism spectrum disorders (ASDs) that are four times more prevalent in boys. High levels of
testosterone during early development have been hypothesized to be a risk factor for ASDs, supported by several studies showing fetal
testosterone levels, as well as indirect measures of prenatal
androgenization, to be associated with ASDs and autistic-like traits (ALTs). Further, the importance of sex
steroid related genes in ASDs is supported by studies reporting associations between polymorphisms in genes involved in sex
steroid synthesis/metabolism and ASDs and ALTs. The aim of the present study was to investigate possible associations between 29 single nucleotide polymorphisms (SNPs) in eight genes related to sex
steroids and autistic features. Individuals included in the study belong to a subset (n=1771) from The Child and Adolescent Twin Study in Sweden (CATSS), which are all assessed for ALTs. For two SNPs, rs2747648 located in the 3'-UTR of ESR1 encoding the
estrogen receptor alpha and rs523349 (Leu89Val) located in SRD5A2 encoding 5-alpha-reductase, type 2, highly significant associations with ALTs were found in boys and girls, respectively. The results of the present study suggest that SNPs in sex
steroid related genes, known to affect gene expression (rs2747648 in ESR1) and enzymatic activity (Leu89Val in SRD5A2), seem to be associated with ALTs in a general population. In conclusion, the current findings provide further support for a role of sex
steroids in the pathophysiology of ASDs.