A new study has found that identical twins with autism spectrum disorder (ASD) experience wide differences in symptom severity. According to a report this month by Scitech Daily, the research was conducted by a team of researchers led by Dr. John Constantino, of Washington University School of Medicine in St. Louis.
Constantino and his team analyzed data from three previous studies, comprising 366 twin pairs with and without autism. The severity of autism traits in the twins was measured using a doctor’s assessment or the ratings of parents on a standard questionnaire. While the researchers found a 96% chance that if one twin had autism, the other would have it as well, they also found that symptom scores varied widely between twins diagnosed with autism spectrum disorder.
The reasons for this symptom disparity currently remain unknown, though the researchers have ruled out genetic and environmental causes, since the twins were raised in the same environment and share the same DNA. The study was published in the journal Behavior Genetics on December 18, 2019.