The molecule has already been associated with conditions like rheumatoid arthritis, multiple sclerosis, and psoriasis, and has been shown to serve an important role in preventing infections, notably those of the fungal kind. Importantly, it can also influence the way the brain develops in the womb.

To test their hypothesis that autism may be triggered by the IL-17a molecule, the team blocked IL-17a in lab mice. The researchers recruited female mice from two separate laboratories – those from the first contained microflora in the gut that made them prone to an IL-17a-induced inflammatory response, whereas those from the second (the control) did not.