An undated image of the human brain taken through scanning technology. The scan shows a person responding to a visual scene, with the imaging technology measuring increases in blood flow to a certain region of the brain.
An undated image of the human brain taken through scanning technology. The scan shows a person responding to a visual scene, with the imaging technology measuring increases in blood flow to a certain region of the brain.
Tangled genes may be the common cause behind many of the spectrum of mental disorders known as autism.
 
That finding, reported in the journal Nature may advance the search for environmental causes of the disorder.
 
Autism spectrum disorders range from inhibited communication and social skills to repetitive behaviors and mental impairment. They affect roughly one person in 160 worldwide.
 
Enzymes called topoisomerases are responsible for removing the kinks that form in DNA during the normal processes of copying and generating instructions for proteins.
 
Researchers report that inhibiting topoisomerases in nerve cells reduces expression of exceptionally long genes, dozens of which are linked to the disorder.
 
They say that many forms of autism could be caused by mutations in the topoisomerase genes or exposure to chemicals that block their action at critical stages of brain development. Identifying those chemicals - the next step for researchers - would allow pregnant women to avoid exposure to those compounds.