Potential causes of autism spectrum disorders : Causes possibles des troubles du spectre autistique

It is possible that the increased number of diagnoses may reflect enhanced awareness of ASD and changing diagnostic criteria, rather than a change in the actual prevalence of the disease. [...] This possibility has been put forward due to the perceived increase in the prevalence of ASD over recent years, the belief that it has appeared as a disorder only recently, and the detection of geographic areas with slightly higher rates of ASD. [...] C. Vaccines, Viruses and Impaired Immune Systems In recent years, considerable public attention was given to the theory that the measles-mumps-rubella (MMR) vaccine, or other combination of vaccines, potentially contributed to the development of autism due to the mercury-containing thimerosal used as a preservative. [...] On the contrary, the observation that the introduction of the MMR vaccine was not followed by a surge in ASD L I B R A R Y. O F. P A R L I A M E N T B I B L I O T H È Q U E. D U. P A R L E M E N T 4 diagnoses is just one of the epidemiological findings that have essentially disproved the vaccine theory. [...] The genetics of autism and the role of retinoids in ASD have recently overlapped with the discovery that retinoids are known modifiers of the proposed autism genes that are members of a family of genes known as the Hox genes.