Autism used to be blamed on the mother and was thought to be the result of so called ‘refrigerator mother’ syndrome. Psychologists in the 1950’s could come up with no explanation for the autistic symptoms seen in children so they blamed the mother and theorized that the symptoms such as disengagement, not making eye contact and not liking hugs were because the mother did not love her child. This theory persisted for years and must have done untold damage to many mothers who thought it was their fault.
Science has now moved on, partly because of the sheer number of children affected by autism and they are exploring multiple factors that may be associated with autism.
Has IVF Contributed to Autism?
Some research in more recent years has suggested that IVF may result in a higher risk of autism. Research by Tel Aviv University found that 10.5% of autistic children studied had been conceived via IVF. This is much higher than the rate in the general Israeli population, which is only 3.5%.
The reason for this may be due to a change in gene expression at a time when the newly conceived embryo is rapidly dividing. During this process, certain genes are selected in the embryo, a process known as imprinting. If the imprinting is skewed or altered in some way by the in vitro environment, prior to the embryo being transferred to the womb, then the genetic disorder could result in disabilities such as autism. Other disabilities, such as Angelman Syndrome, are thought to result from IVF in some cases.
Angelman Syndrome is a genetic disability that is similar to autism and causes developmental delay, seizures, sleep disturbances and hand-flapping, to name a few symptoms. It has been shown to be caused by imprinting defects during IVF, in some cases.
Dr. Zachor, who headed the Israeli research into autism and IVF, said
“Many infertile couples choose this procedure (assisted conception) and they need to know whether there is a risk of autism.”
However, she added
“It's too early to make a serious deduction based on that evidence alone.”
Skewed X Inactivation and IVF
Another thing that could go wrong with artificial reproduction and potentially cause autistic spectrum disorders is skewed X inactivation.
A female mammal (including humans) has two X chromosomes (XX), double the amount that a male mammal has (XY). These X chromosomes contain up to 1,400 genes each. After fertilization of the female embryo, one of the X chromosomes is silenced or inactivated so that both males and females have one active X chromosome. Too many X’s results in disability or death. Examples of disabilities that occur when there are too many or too few X chromosomes are: Triple X Syndrome, XXYY Syndrome and Turner Syndrome. There is also evidence to show that it may be implicated in ASD’s.
The Journal of Autism and Developmental Disorders wrote:
‘Autism is a heterogeneous neurodevelopmental disorder with a 3–4 times higher sex ratio in males. X chromosome genes may contribute to this higher sex ratio through unusual skewing of X chromosome inactivation. Significantly, increased X chromosome skewness was detected in our autism group (33%) compared to unaffected females (11%). X chromosome skewness was also seen in 50% of the mothers with autistic daughters.’
X inactivation imprints may accidently remain on the X chromosome that the mother passes to her children. Because males only have one X, this makes them more vulnerable to this as they do not have a second, paternally given, X chromosome without such imprints. This could explain why substantially more males are affected by autism, compared with females.
A study at the University of Virginia found that there were around 10% more infants with skewed X inactivation born after IVF, than those who were naturally conceived. Researchers wrote:
‘The mean degree of skewed XCI in the IVF group was 72.0% and in the control group was 62.4%. Larger studies are needed to clarify the relationship between IVF and skewed XCI.’
It is therefore theoretically possible that skewed X inactivation after IVF could be contributing to the increasing autism rate in children.
Sources:
- Autism in a Test Tube? American Friends Tel Aviv University (14th June 2010).
- Another case of imprinting defect in a girl with Angelman syndrome who was conceived by intracytoplasmic semen injection. The American Journal of Human Genetics, January 2003.
- X Chromosome, Genetics Home Reference. Page accessed 22nd September 2011.
- Brief Report: Non-Random X Chromosome Inactivation in Females with Autism, Journal of Autism and Developmental Disorders, volume 35, no. 5, October 2005.
- The Imprinted Brain, by Christopher Badcock, Ph.D, Psychology Today, 25th February 2010.
- Skewed X inactivation and IVF-conceived infants, Reproductive Biomedicine Online, Volume 20, Issue 5, May 2010, Pages 660-663.
Joanna Karpasea-Jones - I have been a health writer since 1997 when I published my own newsletter, SHOTS. I have written 2 books on childhood health, and write ...
