A new study involving twins, both identical twins whose genes are identical and fraternal twins whose genes are similar suggest that the environment may have greater function than was commonly thought.
The study is out of Stanford and was published on Monday July 4th in the Archives of General Psychiatry. The lead author is Dr. Joachim Hallmayer and evaluated 192 twins from
Identical twins are clones of one another, therefore if autism were purely genetic, then it would be expected that if one twin were identified as having autism then the other should logically have autism also. This however is not what the new autism twin study found. The study group revealed 77 percent of male twins with autism both had autism, while 50 percent of female twins had autism. Autism is 4 times more likely to occur in boys. If these children were identical twins, why aren't the rates 100 percent for boy twins and girl twins? The environment would have to explain 23 percent and 50 percent respectively.
Rates of fraternal twins who both had autism were also high. Fraternal twins don't share the same egg and therefore have different genetic makeups but -do share the same womb.
Traditional thought in autism research is that genetics are the dominant factor in autism spectrum disorders but this is apparently changing, as we are seeing as of recent that there have been more indicators that environment plays a significant role in the increasing autism statistics. Identifying these factors may lead to prevention which is even better than early intervention.
Our model has always been one of environmental influences on gene expression and so I am thrilled as this may shift more research dollars into looking for environmental factors, along with research focus not only to environmental factors but more specifically to issues relating to the pre and post natal environment.
Factors such as:
- Medications such as Antidepressants
- Maternal Age and Paternal Age
- Time between Births
- Premature Birth,
- Low Birth Weight,
- Toxin Exposure
These factors have all been identified previously in autism spectrum disorders.
This research is just one more step toward identifying the cause or multiple causes of Autism, leading to effective treatments and possibly prevention”.
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