Although individuals with autism spectrum disorder (ASD) appear to have a higher number of mutations in oncogenes (genes with the potential to cause cancer), they actually have lower rates of cancer, according to a new study at the University of Iowa.
The multidisciplinary team analyzed gene databases of patients with autism and found that autistic patients have significantly higher rates of DNA variation in oncogenes compared to a control group.
The researchers then followed up this finding with an analysis of electronic medical records (EMR) and discovered that patients with a diagnosis of autism are also much less likely to have a co-occurring diagnosis of cancer.
“It’s a very provocative result that makes sense on one level and is extremely perplexing on another,” says Benjamin Darbro, M.D., Ph.D., assistant professor of medical genetics in the Stead Family Department of Pediatrics at the UI Carver College of Medicine.
The researchers compared 1,837 patients with autism spectrum disorder to 9,336 patients with any other diagnosis, and determined what proportion of each group of patients carried a cancer diagnosis. They found that for children and adults with ASD there appeared to be a protective effect against cancer.
Specifically, 1.3 percent of patients with ASD also had a diagnosis of cancer compared to 3.9 percent of the control patients. This protective effect was strongest for the youngest group of patients and decreased with age.
For ASD children under 14 years of age, the odds of having cancer were reduced by 94 percent compared to individuals in the same age range without autism. Both males and females with ASD demonstrated the protective effect.
When the research team determined the rates of other systemic diseases besides cancer in the autistic population, such as high blood pressure and diabetes, they found no relationship.
Furthermore, unlike what they found for autism, they found no relationship with cancer when they examined the rates of other common conditions such as heartburn (esophageal reflux), allergies (allergic rhinitis), eczema (atopic dermatitis), and short stature.
Darbro pointed out that autism is also one symptom of many inherited cancer syndromes caused by mutations in a single gene. In fact, several genes implicated in causing hereditary tumor syndromes overlap with those involved in neurodevelopmental disorders such as autism.
“The overlap in genes between those known to promote cancer and those implicated in syndromic neurodevelopmental disorders is not new, but what we’ve shown is that this overlap is much broader at the genetic level than previously known and that somehow it may translate into a lower risk of cancer,” Darbro said.
The findings raise questions that could pave new avenues for treating both cancer and ASD. For example, could the genetic variants that appear to protect against cancer in ASD individuals be harnessed to develop new anti-cancer treatments? Or could current cancer drugs that target the genetic pathways found to overlap with ASD also be useful for treating ASD?
This last question is currently being explored in clinical trials as scientists test the potential benefits of an anti-cancer drug for autism patients.
The study was published recently in the journal PLOS ONE.
Source: University of Iowa Healthcare