The symptom severity of three girls with fragile X syndrome tracks with how much the levels of the fragile X protein in their blood differs from that of their unaffected mothers. If the results, published 29 January in Molecular Syndromology, are confirmed in a larger study, they may help doctors predict how the disorder will manifest in girls.

Roughly one-third of children with fragile X syndrome also have an autism diagnosis. Studies published in the past few months, however, suggest that the set of autism-like symptoms seen in people with fragile X syndrome may only resemble autism superficially.

Following disappointing results from two clinical trials, the Swiss pharmaceutical company Novartis announced on 24 April that it will stop development of a drug candidate for fragile X syndrome.

By age 2, children with autism show difficulty with movement, communication, emotional control and problem-solving, distinct from the symptoms of children with other disorders, reports a study published in February.

A new statistical system ranks the potential harm done by each of the nearly 9 billion possible variants in the human genome, researchers reported in March in Nature Genetics.

Mutations in a gene associated with DNA packaging may lead to autism and intellectual disability, suggests a study published 16 February in Nature Genetics.

Many characteristics of Phelan-McDermid syndrome — an autism-linked disorder arising from abnormalities at the tip of chromosome 22q13 — change as individuals age.

Do genetic differences or diagnostic biases account for the gender imbalance in autism? Catherine Lord, David Skuse and Angelica Ronald weigh in.

Two studies published in the past month lend support to the notion that autism looks different in girls than it does in boys, making it harder to recognize and diagnose in girls. The studies reflect growing suspicion in the research community that the underlying biology and the experiences of girls with autism may both be distinct.

A teenager with fragile X syndrome carries a rare mutation that changes a single amino acid in the FMRP protein, researchers reported 22 January in the European Journal of Human Genetics.