Genes and the environment each influence the role of the other in determining the risk of developing autism. Genetics can determine how susceptible one is to the environment, and environmental factors can influence gene expression and introduce mutations, says immunologist Janine LaSalle.

The assumption in some published overviews of autism tends to be that all of the problems relevant to the disorder can be found at synapses, the junctions between neurons. But it’s difficult not to notice the striking number of chromatin-associated genes that have emerged as candidate risk factors over the past few months.

Identical twins are born with significant differences in the chemical modifications to their DNA, suggesting that the uterine environment can profoundly influence development and risk for disease.

The absence of a chemical alteration called methylation on some stretches of DNA makes them especially prone to mutations, according to a paper published in PLoS Genetics in May.

Normal aging triggers dramatic changes to the epigenome, the set of chemical tags that turn genes on and off, according to a new study.

By studying pregnant women who already have a child with autism, researchers hope to understand how epigenetic changes — those that affect gene expression but don’t directly alter DNA — during pregnancy influences risk of the disorder.

A commonly used flame retardant may lead to deficits in sociability, learning and memory in healthy female mice and those that model Rett syndrome, according to a study published 15 February in Human Molecular Genetics. The effects are different in Rett syndrome models compared with healthy mice, suggesting gene-environment interactions.

Researchers have charted patterns of DNA methylation — a chemical alteration to DNA that modifies gene expression — in the planning center of the brain from before birth to old age. The results were published 10 February in The American Journal of Human Genetics.

A new study reveals the three-dimensional structure of fruit fly chromosomes, which groups together active and inactive genes. The results were published 3 February in Cell.

Autism and attention deficit hyperactivity disorder show genetic and neurobiological overlap, which may provide clues to the origin of both disorders, says Joel Nigg.