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Scientists Find Autism Can Be Largely Down to Genes


Image credit: hepingting, “Autism,” via Flickr. CC BY-SA 2.0

While it is not quite clear about how autism is caused at present, both genetics and the environment are closely linked with it according to the prevailing idea. However, it is still difficult to establish the relevant contributions of these two factors associated with autism.

Based on the investigation of quite a number of twins in the U.K, researchers have once again stressed the part genetics played in autism. However this current study did not concentrate more on environmental impacts compared with some previous researches.

Such investigation has demonstrated that autism could be greatly influenced by genetic factors, because 74-98% of autism cases are attributed to genes. Although it is not exactly known which genes are involved at the current stage, researchers have noticed genes are likely to play a part in this regard, namely tens could be possible, if not hundreds.

Of course, in this study, scientists were still considering the possibility that environmental factors did have something to do with the development of autism. From the conclusion of a study finished last year, it confirmed that the environment and genetics were equally important, but as for what these environmental factors, it was not quite clear yet.

Autism Spectrum Disorder (ASD) is kind of collective concept in description of some neurodevelopmental disorders, such as autism and Asperger’s syndrome, which have obvious impacts social interaction, behavior and communication. Even though it remains unknown about the origins of ASD, environmental factors are possibly having their influences, because the diagnoses have remarkably increased recently. For instance, the diagnosis of ASDs in the U.S have been going up 10-fold during the ten-year period, that is increased from 4-5 children per 10,000 in the ‘80s to 30-60 in the ‘90s.

Although there have existed several different ideas about the  explanation of such situation, for example, the previous discredited study had associated autism to the MMR, many believe it might simply be the result of our better understanding of the condition as well as improved diagnostic criteria.

As it was clearly doubted about the etiology of ASD, researchers from King’s College London had decided to be engaged in a study for further investigation.

In the paper published in JAMA Psychiatry, they described that based on data regarding all twins born in England and Wales from 1994 to 1996; they had made the evaluations on 258 pairs of twins among nearly 6,000 tested in the initial group. It is useful to deal with twins, because in genetics, identical twins share 100% of their DNA, by doing so, it is easily found whether the environment is attributed to the differences to be observed.

According to diagnostic interviews and observation of their playing, they found 181 twins diagnosed with ASD. In the following step, after comparison of identical and non-identical twins, it was demonstrated that the rate of ASD was remarkably higher in the former, which showed that it was highly heritable. Their further analysis allowed them to believe that in 74-98% of cases, genetic factor was the cause of ASD.

As Dr. Francesca Happé, study author said, it was quite important for them to know from their current findings that environmental factors were much smaller, because some parents were worried that autism would be caused by about serious pollution. The current consensus related to rise in diagnosis was due to enhanced awareness of the condition.”

Source: BBC

Journal reference: Colvert, Emma, et al. “Heritability of Autism Spectrum Disorder in a UK Population-Based Twin Sample.” JAMA psychiatry (2015).

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