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Scientists: Autism develops due to environmental influences
Last reviewed: 16.10.2021
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Research scientists at Stanford University (USA) say that in most cases, the causes of autism spectrum disorders are not in the field of genetics, but can be attributed to the influence of the environment.
Recently, it is extremely popular to attribute the cause of autism to malfunctioning genes (the fact that hundreds and hundreds of such genes do not seem to embarrass anyone). In favor of this hypothesis, the apparent hereditary nature of this mental disorder speaks: it is estimated that in 90% of cases autism is transmitted along with genes. However, the results of the study, presented by a group of scientists from Stanford University in the journal Archives of General Psychiatry, suggest the opposite: in most cases, autism can occur due to non-genetic factors - for example, the age of parents, the condition of ripening of the fetus during pregnancy and other things.
Scientists observed families with born in the period from 1987 to 2004 twins, at least one of whom had autism spectrum disorders. In 77% of cases, both twins got sick with autism, which is not surprising, since they carry an identical set of genes. Differences from the "genetic" hypothesis, according to the researchers, began when they drew attention to the heterozygous twins, whose genetic sets are no more similar to each other than ordinary children born at different times. In such twins, the coincidence rate was 31%. However, in previous studies that took into account the heterozygous twins, it was claimed that the probability of occurrence of autism in both children is almost zero.
These data lead to a new look at the role of the environment in the occurrence of autism spectrum disorders. In general, the authors evaluate the influence of genetic factors in the development of classical autism and other autistic disorders (say, Asperger syndrome) by 37-38%. Consequently, they "blame" the environment in 55-58% of cases.
Supporters of the genetic origin of autism could not pass by these "outrageous" data. The main complaint addressed to the authors was what they are looking for where it is light; in other words, the researchers mostly dealt only with families where both twins were autistic. This may not necessarily have been a malicious intent: couples who were twice affected by this incomprehensible disorder could more easily contact scientists. Critics of the work, recalling also the times when parents blamed everything (they say, their coldness and negligence leads to autistic disorders), it is said that it is important not to allow resuscitation of such a point of view, which was hard to shake the efforts of psychologists and geneticists.
On the other hand, now there is a reverse picture, when every sneeze is attributed to the action of a gene, and are genetically influenced to explain everything from political views to love of classical literature. In general, it's a good time to remember a well-known scientific stamp stating that "this issue requires further study".
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