Microscopic stained image of the MeCP2 gene (in red) in the hippocampus section of a rat's brain

Credit: R. Logan& J. Eubanks/Neurology

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PERTH, 11 August 2006: A devastating brain disorder, triggered by a genetic flaw and thought to strike only girls, can also affect boys - even where there isn't a family history of the disease - Australian researchers have discovered.

Known as Rett syndrome (or Rett's disorder), it is a progressive neurological ailment commonly confused with cerebral palsy. Symptoms include learning disorders and a total inability to socialise.

Helen Leonard of the Telethon Institute for Child Health Research in Perth and leader of the new study, said her team had found that the genetic flaw responsible for Rett syndrome – carried on the X chromosome – can also surface in boys with no family history of the disease.

"The common thinking in the past had been that Rett syndrome only affects girls, and that the genetic flaw would be so serious in boys that they would die before birth," said Leonard, whose study was published in the international journal, Neurology.

"Our research means that boys who die of severe disabilities without diagnosis could, in fact, have been suffering from Rett syndrome," she added. "A lot of children die without a diagnosis and we would urge doctors to consider testing for Rett syndrome as a possible cause of severe neurological abnormalities."

A diagnosis would, she said, not only give families peace of mind but allow mothers who have children with the disease to receive prenatal testing in future pregnancies.

Researchers in Perth and the United States found four boys with the disease. One, from Perth, was diagnosed by pathologists after his death. The severe disease, which strikes one in 10,000 girls, could now be more widespread than previously thought. It is often misdiagnosed as autism as well as cerebral palsy.

"I would like to now pursue further research to test a cohort of boys to find out what proportion actually had or have it," said Leonard, who heads the Australian Rett Syndrome Study.

"Genetic testing is used to diagnose Rett syndrome in girls who present with typical symptoms after the age of one year. Prenatal diagnosis is also available in subsequent pregnancies for mothers of girls with Rett syndrome but beyond these families, doctors generally wouldn't test for the problem - especially in baby boys."

She says boys with the disease have such severe breathing problems that they usually die before the age of two.

The Australian Rett Syndrome Study is the only population-focused study of its kind in the world, attempting to research every child born with the condition since 1976.

Rett syndrome is caused by one of more than 200 spontaneous mutations to the MeCP2 gene, which is critically important for balance, learning and movement. Children with Rett syndrome appear to develop normally until six to 12 months of age when development stops.

Over the next few months, they lose hand and communication skills and, over time, develop digestive, mood and breathing disorders, scoliosis or spinal curvature and epilepsy.

The involved researchers from Princess Margaret and Royal Perth hospitals, the Western Australian Institute for Medical Research and the Children's Hospital in Sydney.