[Autism in females: clinical, neurobiological and genetic aspects]

Autism spectrum disorders are more prevalent in males than in females, and the proportion can range from 1.4 to 1, depending on the samples that are analysed. The smaller difference has been related to those who also manifest an associated intellectual disability, and it is accepted that in those cases females are far more seriously affected. There is likely to be a subregister of females with autism spectrum disorder, especially in those who have high cognitive performance, that is possibly related with the assessment techniques that are used and even with the lack of suitable levels of arousal in girls. In general, females with autism have better early language development, better social skills and their playing can even develop in the expected way. Their interests can be similar to those of their peer group, although they usually vary in intensity and quality. It is accepted as a fact that the difference in the social skills becomes more apparent in adolescence. The extreme male brain theory, the female-specific protective factor, variants in brain plasticity (lower threshold in males with greater susceptibility) and genetic and epigenetic factors, among others, are put forward as possible hypotheses to justify this lower prevalence and the clinical variants in females. This work aims to analyse the clinical and developmental aspects, the variability of expression in females with respect to males, and some of the possible neurobiological and genetic bases that account for the higher prevalence and the differences in expression.