A combination of genetic and environmental factors may act synergistically to boost the risk of certain neurodevelopmental disorders.

In humans, mutations in NURR1 — a gene vital for the normal development of neurons that produce a neurotransmitter called dopamine — are thought to slightly raise the risk of neurodevelopmental disorders. The risk is similarly increased by infection in the mother during pregnancy. To test the combined effect of these two factors, Urs Meyer at the Swiss Federal Institute of Technology in Zurich and his colleagues activated the immune system of pregnant mice that had only one copy of the Nurr1 gene.

They found that dopaminergic development in key parts of the brain was impaired in Nurr1-deficient pups born to immune-activated mothers. As adults, these mice were unable to sustain or shift attention normally, a characteristic of neurodevelopmental diseases such as schizophrenia and attention-deficit hyperactivity disorder.

J. Neurosci. 32, 436–451 (2012)