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Spectrum: Autism Research News

Scientists take steps to clarify Rett syndrome’s diversity

by  /  2 September 2014
THIS ARTICLE IS MORE THAN FIVE YEARS OLD

This article is more than five years old. Autism research — and science in general — is constantly evolving, so older articles may contain information or theories that have been reevaluated since their original publication date.

Lost grasp: Children with Rett syndrome seem to lose some skills they had as babies, particularly fine motor skills such as grasping.

Rett syndrome, a neurological disorder that shares some features with autism, can be severe and debilitating. But some people with the disorder can regain social skills years after diagnosis.

That diversity in outcomes may be due to different genetic causes: Most cases of Rett syndrome arise from mutations in the gene MeCP2, but some are caused by alterations in other genes.

Because of this, some researchers say that symptoms, rather than a genetic screen, should be used to diagnose people with the syndrome. Clear and accurate characterization of the disorder could improve people’s lives and help parents know what to expect when their children are diagnosed.

Two studies published last month assessed females with Rett syndrome, with this goal in mind.

The first, published 22 July in the Journal of Neurodevelopmental Disorders, looked at 542 girls with so-called classic Rett syndrome and 96 with an atypical version of the disorder. Atypical cases include those that lack some of the disorder’s hallmarks: loss of speech and functional hand movements at 6 to 18 months of age, hand flapping and stiff gait.

All the girls were enrolled at younger than 10 years so that the researchers could be sure that their parents’ memories of them as babies were still somewhat fresh.

Nearly all the children were able to roll, sit without support, coo and smile when smiled at as babies. However, most of them showed distinct lags compared with typically developing children.

Few of the children ever gained the most advanced skills the researchers looked for, including riding a tricycle. The girls with classic Rett and those with atypical Rett both lost skills they’d had as babies, especially fine motor skills such as pinching fingers together.

Changing patterns:

The findings may help clarify whether children with Rett syndrome regress, as researchers have long thought, or show deficits from birth. The study found that some children show delayed development even before 6 months of age.

The second study, published 3 July in Neuropsychiatric Disease and Treatment, investigated how capable individuals at various stages of the syndrome are at self-care, walking or sitting up unassisted, and socializing.

Clinicians use four stages to classify the syndrome’s progression. The first two stages involve a lot of rapid change, so the researchers focused on the latter two. They looked at 38 girls and women, ranging in age from 2 to 26 years, in the third stage of the disorder. This stage often involves obvious problems walking and frequent seizures. They also looked at 22 girls and women (aged 5 to 27) in the fourth stage, which involves less severe seizures but even more difficulty moving. People at this stage of the disorder frequently need to use a wheelchair.

As the researchers expected, the main difference between these two stages is that people in the third stage are better able to walk and move around. However, with assistance, most people with Rett syndrome can move from a lying to a sitting position, the study found. This position can more pleasant and help them accomplish other tasks with their hands or better communicate if they can.

In fact, the researchers found that many individuals with Rett are better at communicating nonverbally than verbally, but that attention to their gestures is necessary to recognize these attempts.

People with Rett syndrome are living longer than they did when the disorder was discovered. This may be due to a better understanding of the risks involved in the disorder — for example, seizures can exacerbate cognitive and motor problems or even cause sudden death, but doctors can use medications to manage the seizures.

Together the two new studies emphasize that even people with severe cases of Rett can be encouraged to maintain useful skills. A push from caregivers to do so, along with vigilance to preserve health, could improve the length and quality of their lives.