New evidence implicates the neurotransmitter glycine, which dampens brain signals, in autism.

Researchers in Sweden are assembling a large group of identical twin pairs, with only one twin in each pair having autism.

Blocking an enzyme involved in learning and memory corrects brain abnormalities and improves memory in fly and mouse models of fragile X syndrome.

Drugs that activate the silent copy of the X chromosome in women may be able to undo the damage from mutations in genes located there. The study, published 2 September in Proceedings of the National Academy of Sciences, offers hope for treating Rett syndrome and other disorders linked to the chromosome.

As they age, children with fragile X syndrome may become worse at adapting to change, according to a study published 28 July in Pediatrics.

The protein missing in fragile X syndrome is necessary for mice to respond to the stimulant cocaine, according to a study published 7 May in Neuron.

Girls and boys born with an extra X chromosome both tend to have difficulties understanding the minds of others, but for different reasons than children with autism do, according to a study published 22 March in Genes, Brain and Behavior.

A teenage girl with Rett syndrome has a mutation in WFR45, a gene that is mutated in people who abruptly lose motor and mental skills in adulthood, according to a study published 13 March in the Journal of Human Genetics.

People with autism tend to carry mutations that duplicate or delete several genes at once, according to a large study published 1 May in the American Journal of Human Genetics.

Support cells generated from people with Rett syndrome release molecules that alter the shape and function of neurons, according to a study published 27 February in Human Molecular Genetics.