New Study Emphasizes Environmental Factors in Cause of Autism

A new study is finally shifting the official discussion of the cause of autism from mainly heredity to a combination of genetic and environmental influences. 

Researchers examined 192 pairs of identical and fraternal twins whose cases were drawn from California databases. At least one twin in each pair had classic autism and in many cases, the other twin also had classic autism or Asperger’s Syndrome. Since identical twins share 100 percent of their genes and fraternal twins share 50 percent of their genes, comparing autism rates in both types of twins enabled researchers to measure the importance of genes versus shared environment.

Results demonstrated that autism or autism spectrum disorders occurred in both children in 77 percent of the male identical twins and in 50 percent of the female identical twins. Confirming their hypothesis, rates among fraternal twins were lower: 31 percent of males and 36 percent of females. Yet mathematical modeling suggested that only 38 percent of the cases could be attributed to genetic factors, compared with the 90 percent suggested by previous studies. Most surprising to the researchers is that shared environmental factors appeared to be at work in 58 percent of the cases.

Because the rate of autism occurring in two siblings who are not twins is much lower, conditions the twins shared in the womb, rather than what they were exposed to after birth appeared to have contributed to the development of autism.

As a mother of fraternal twins who both have high function autism, this news is unremarkable. Many of the Rho(D) immune globulin shots for mother/child blood incompatibility contained mercury even after it was officially removed from vaccines. The rise in the number of c-sections corresponding to the rise in autism calls obstetric drugs into question. Mothers giving birth later in life and prematurity, common in cases of twins are acknowledged red flags. A companion study to this one notes high risk of autism amongst mothers-to-be taking anti-depressants. 

In the world of science in which hypotheses must be proven, it’s good news that this study will cause more attention to be paid to environmental factors inducing autism. Now that Pandora’s box is open, let’s not confines ourselves to in utero influences.

5 Responses to New Study Emphasizes Environmental Factors in Cause of Autism

  1. Bob Deschenes says:

    Very informative Would the area you live in have anything to do woth autism? I have relatives and friends that have autism in their kids. (3) There are also others in the area

  2. Susan says:

    They are finding autism concentrated in certain areas such as New Jersey and have begun to ask why.

    There’s also been a correlation found between autism and living near freeways.

    Susan Moffitt

  3. Rachael says:

    So, now it’s the genes and an environmental trigger, that have caused the dramatic spike in autism cases. Researchers will now spend millions of dollars looking into every possible environmental trigger (antidepressants, chemical exposures, living near freeways etc) everything except vaccines of course. Genes load the gun, but environmental factors (including vaccines) may pull the trigger in those who are genetically predisposed to develop autism.

  4. Rachael says:

    Dr Andrew Wakefield’s retracted Lancet study from over a decade ago ( the one that started all the controversy about the MMR vaccine) stated that: A genetic predisposition to autistic spectrum disorders is suggested by over-representation in boys and a greater concordance rate in monozygotic than in dizygotic twins. In the context of susceptibility to infection, a genetic association with autism, linked to a null allele of the complement C4B gene located in the III region of the major-histocombatibility complex, has been recorded by Warren and colleagues. C4B-gene products are crucial for the activation of the complement pathway and protection against infection; individuals inheriting one or two C4B null alleles may not handle certain viruses appropriately, possibly including attenuated strains. We identified associated gastrointestinal disease and developmental regression in a group of previously normal children, which was generally associated with environmental triggers. Ileal-lymphoid-nodular hyperplasia, non specific colitis, and pervasive developmental disorder in children.’ The Lancet 1998 A J Wakefield, S H Murch, J A Walker-Smith

  5. Susan says:

    There’s no want of environmental triggers in our modern world, and yes, I hope this study help moves the vaccine debate forward.


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Did You Know?

  • * In 1970, Autism affected 1 out of 10,000 children
  • * Autism now affects 1 out of 88 children
  • * Autism affects 1 in 54 boys
  • * 1.7 million Americans have some form of autism
  • * 4 out of 5 autistic children are boys

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