Do twins have a higher incidence of autism?
Several small studies conducted over the last three decades have found that it is much more common for identical twins to be diagnosed with autism than it is for fraternal twins.
How common are autistic twins?
The percentage of fraternal twins who each share an ASD diagnosis is 34 percent for same-sex twins and 18 percent for boy-girl pairs, Dr. Frazier said. (Girls are less likely to be diagnosed with autism than boys). Those statistics are similar to other twin studies, including the California one.
Why is autism more common in twins?
Most of the risk of autism has been blamed by experts on inherited genes. Now one of the largest studies of twins and autism shifts the focus to the womb, suggesting that the mother’s age and health may play a larger role than thought.
Can one twin have Aspergers?
In identical twin sets where both children had some form of ASD, it was very unusual for one to have Asperger’s and the other to have autism or PDD-NOS. In other words, when one identical twin had Asperger’s, the other usually, did, too.
Are twins more likely to have disabilities?
A number of studies have shown that, even among children of similar birth weight and gestational age, twins are more likely to suffer from the disorder.
Are twins more likely to have mental illness?
The strongest risk factor for suicide is mental illness and studies show that mental illness is slightly more common among twins.
Is it possible for only one twin to have autism?
The researchers determined a 96% chance that if one twin has ASD, the other has it, too. However, symptom scores varied greatly between twins diagnosed with ASD. The researchers estimated that genetic factors contributed to only 9% of the cause of trait variation among these twins.
Why is autism more common in boys?
A new study offers clues to why autism spectrum disorder (ASD) is more common in boys than in girls. National Institutes of Health scientists found that a single amino acid change in the NLGN4 gene, which has been linked to autism symptoms, may drive this difference in some cases.
Do twins have developmental delays?
Conclusions: Healthy twins should be considered at a higher risk for developmental delay. Whether these results are comparable to preterm singletons, or whether there are twin-specific issues involved, should be further investigated in a study that uses a matched singleton control group.
Do twins have a lower IQ?
On average, twins have lower IQ scores at 7 and 9 years old than singleton children in the same family. In a cohort study, Ronalds and colleagues (p 1306) used data on 9832 singletons and 236 twins born in Aberdeen between 1950 and 1956.
Can one twin have schizophrenia?
In twin studies looking at schizophrenia, scientists have shown that if one identical twin has schizophrenia, then there is a 30-50% chance that the other twin will have it as well1. If a fraternal twin has schizophrenia, then there is a ~15% chance that the other twin will have it too1.
Is bipolar common in twins?
Because identical twins share all the same genes, if bipolar disorder were purely hereditary, then all identical twins would share the disorder. However, it has been found that if one identical twin has bipolar disorder, the chances of the other twin also having bipolar disorder ranges from 40% to 70%.
What are the chances of a twin having autism spectrum disorder?
If one identical twin has autism spectrum disorder (ASD), the other twin has a 76 percent chance of also being diagnosed with it. The numbers are lower for fraternal twins. The percentage of fraternal twins who each share an ASD diagnosis is 34 percent for same-sex twins and 18 percent for boy-girl pairs, Dr. Frazier said.
Do fraternal twins have a higher rate of autism?
The numbers are lower for fraternal twins. The percentage of fraternal twins who each share an ASD diagnosis is 34 percent for same-sex twins and 18 percent for boy-girl pairs, Dr. Frazier said. (Girls are less likely to be diagnosed with autism than boys).
Do identical twins with autism have different cases of ASD?
Previous studies have found that when one identical twin has ASD, chances are extremely likely that the other twin has it, too. The authors analyzed data from three previous studies comprising a total of 366 identical twin pairs with and without ASD.
What is the largest study on autism twins?
Dr. Frazier had questions about the California study, so he decided to launch his own autism twins study, the largest of its kind so far. His team analyzed information about 568 pairs of identical and fraternal twins in the Interactive Autism Network (IAN) database. 1