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.

Small duplications or deletions of DNA regions — called micro-copy number variations — may not lead directly to disease, but could raise the risk of autism when combined with other mutations, according to a study published in March in the American Journal of Medical Genetics Part B: Neuropsychiatric Genetics.

Two children with Asperger syndrome have disruptions in the PARK2 gene — one child has a duplication in the gene whereas the other has a deletion — according to a study published in February in the American Journal of Medical Genetics.

Children with autism or attention deficit hyperactivity disorder (ADHD) are both more motivated by money than by praise, according to a study published in January in the Journal of Child Psychology and Psychiatry.

Areas of the brain that are active when people are daydreaming or sleeping, and quiet when they are engaged in a task, are imperfectly synchronized in people with autism and attention deficit hyperactivity disorder, researchers say.

Better performance on intelligence tests that measure spatial rather than verbal ability is inherited in people with autism, according to a paper published online in October in Human Genetics.

Can your brain be trained to make better brain waves? That’s the bizarre premise of ‘neurofeedback,’ a technique in which participants don a cap of electrodes and are rewarded — with soothing music, say, or points in a video game — for ‘desirable’ brain activity.

Individuals with attention deficit hyperactivity disorder (ADHD) have a higher rate of DNA duplications and deletions, including some in regions linked to autism and schizophrenia, according to a study published 23 October in The Lancet.

For a few hundred dollars and a bit of your spit, you can have parts of your DNA analyzed. If you’re more ambitious, $20,000 — and a lot less than that a year from now — will buy you the sequence of your entire genome. But the real question is should you, and others like you, find out what secrets your genome holds?

Three articles published in the past few weeks show that diagnostic categories marked off neatly on the page often bleed together messily in the clinic.