A genetic mutation that causes defects in the insulation of neurons may contribute to the cognitive deficits seen in autism and other neuropsychiatric disorders.

Pratik Mukherjee of the University of California in San Francisco and his colleagues used magnetic resonance imaging to study the brains of 23 children with a deletion in a region of the genome associated with such disorders.

The authors found that in these children, the white matter, which helps signals travel between neurons, was structurally defective. The children scored lower on non-verbal IQ tests (such as visual recognition and memory) than those without the genetic deletion.

J. Neurosci. 34, 6214–6223 (2014)