Aspergers and Identical Twins


Out of curiosity, is Aspergers relatively common amongst twins who have been affected by TTTS before birth, specifically the 'donor' sibling? I was thinking of the link with oxygen starvation being the common denominator. Many thanks, by the way love the website/emails!!


For those who may not know, TTTS is a disease of the placenta. In a normal multiple birth pregnancy, some blood vessels are shared between the babies and blood flow between them is equal. One minute one baby will act like a donor, the next it will act as a recipient. In a pregnancy with TTTS, for some reason, the blood flow isn't equal between the babies. One baby will always be the donor and the other always the recipient. This causes one baby to be larger than the other.

Having said this, there is no solid research currently that suggests a link between TTTS and Autism Spectrum Disorders. However, new research with rats suggests that “oxygen deprivation” (one byproduct of TTTS) during birth could be a contributing cause of Autism.

There's no easy way to test the oxygen-deprivation theory in humans, and the finding isn't likely to lead to better treatments in the near future. Still, the research gives scientists greater insight into how factors other than genetics may play a role in autism.

Research reveals that when one identical twin develops an Autism Spectrum Disorder (ASD), the risk of the other developing it is substantially higher than it is for fraternal twins (approximately 88% higher). That compared with 31% among fraternal twins (unlike identical twins, fraternal twins are no more genetically similar than non-twin siblings). Identical twins also have greater similarities in the form of the ASD that they developed, their level of day-to-day functioning, and the risk of intellectual impairment.

Autism research has been guided by one important observation for the past several decades – that it has a large genetic component. That observation was made through twin studies. We show that important characteristics of ASD, such as the type of ASD, level of functioning and presence of other psychiatric disorders are more similar among identical twins. Thus not only are they more concordant overall, but the pattern of their disease is more concordant.

While experts generally agree that genetics plays a major role in ASDs, they also believe that environmental factors conspire with genes to make certain children vulnerable. Researchers are still trying to figure out what those environmental factors are.

The Aspergers Comprehensive Handbook


  1. My brother and sister are fraternal twins and my brother has it while my sister does not, although identical twins would most likely both have it because they have the same genetic make-up.

  2. I saw a program on TV recently about research into medical conditions in identical twins. Autism was one of the conditions mentioned and often both twins had it and to the same degree, but occasionally one would have it but the other wouldn't. The scientists were trying to find out why this happened and thought it could be due to environmental issues, eg. something happened to one of the babies while developing in the womb which could cause autism, or could cause already existing autism to be higher or lower functioning. It was very interesting as I'd always assumed identical twins were completely identical in every way including medical conditions.

  3. I am an identical twin. I've just discovered AS, I'm pretty sure I have it, and I need to get diagnosed. I also believe I have Tourette's Syndrome. I've talked with my twin about these things. She also believes she has Tourette's, but hasn't expressed any inclination that she also has AS, and I feel that she either doesn't have it or has a much lesser degree if she does. I tend to agree that the egg does not split exactly in half. My twin and I have many similarities, but also many differences.

    1. If you have a twin SISTER, you didn't come from the same egg. :) You are just siblings (same mother and father) born at the same time, no different than any other brother and sister in genetic makeup. You have to be the same gender to be from an egg that split (identical twins).

  4. Even though it has been shown that aspergers has genetic links, genes are tricky. Twins with identical DNA can have different phenotypic traits (phenotype being the term used to describe the physical result of genes). This is because genes need to be turned on during development to be active, and if they don't get the right signal, they'll never do anything. It's not likely for the gene(s) to be active in one twin and not the other, but it is possible.

  5. My daughters are identical twins and one has sever autism were as the other has aspergers syndrome.

  6. I have identical 2 year old twins, and we have within the past six months or so found out there are some significant developmental delays and possible ASD concerns. They were mono chorionic, but there was no issue of TTTS during pregnancy, although I was monitored very closely for that possibility. Initially, the ASD concern was expressed concerning just one of my babies, but I am now seeing the exact same behaviors of concern in my other one. My very uneducated observation is that if P has ASD, so does A. I am an older mom. I gave birth at 40, and wonder if that is a factor as well. Regardless, we are working with an early intervention program and have the babies in speech and OT and are seeing tremendous gains. From talking to other parents, early intervention is key.


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