The placenta regulates the levels of the neurotransmitter serotonin in the brains of mice at a key stage in embryonic development, according to a study published 21 April in Nature. The results suggest that the fetal environment can influence the long-term mental health of children, including whether they later develop autism or schizophrenia.

Two large studies published in the past two months have found that traits linked to autism are widely distributed in the general population. Although about 1 in 100 children is diagnosed with autism, up to 30 percent of people may have at least one of the traits associated with the disorder.

Identical twins can be genetically different, which could explain why they do not always share disorders such as schizophrenia or autism, according to a study published in March in PLoS One.

Mice that lack the gene for integrin β3, or ITGB3 — which regulates the levels of serotonin in the blood — groom themselves frequently and show less interest in stranger mice compared with controls, according to a study published in February in Autism Research as part of a special issue on mouse models in autism.

Six strains of mice lacking a gene associated with fragile X syndrome show radically different behaviors though they share the same mutation, researchers reported in January in Autism Research.

Autism is popularly viewed as a disorder of childhood, not old age, but that doesn’t mean senior citizens are unaffected.

High levels of serotonin in the womb may up the risk of autism in the child, according to a study published in December in the American Journal of Medical Genetics.

As more drugs enter clinical trials for fragile X syndrome and soon, hopefully, for autism, the placebo effect will become an important consideration.

Depression in mothers of children with autism may not be a consequence of their child’s condition, but of their own genetic profile, says a provocative new study.

A new wave of genetic tests for fragile X syndrome, the leading cause of inherited mental retardation and the most common genetic cause of autism, may make it possible to routinely screen pregnant women and newborns for the syndrome.