What Is Rett Syndrome?

Rett syndrome is a brain development disorder that affects mostly females. A change in a gene called MECP2 causes Rett syndrome.

Girls with Rett syndrome appear normal when born and as young infants. Usually by 6 to 18 months, learning slows down and girls begin to lose some language and motor skills. This loss eventually stops and development stabilizes, but girls with Rett syndrome have serious life-long problems with learning, speech, and movement. One of the classic signs of Rett syndrome is repeating hand movements over and over, like hand wringing or clapping that has no purpose. Other signs may include slowing head growth, autistic-like behaviors, severe communication problems, breathing irregularities, sleep disturbances, and seizures.

This combination of symptoms is called "classic" Rett syndrome. Sometimes the signs of Rett syndrome are more or less serious – or the signs start earlier or later than usual. These variations are called "atypical" or "variant" Rett syndrome. For example, there is a milder kind of variant Rett syndrome where girls still have relatively normal speech. Also, a much more severe kind may start from birth and cause serious seizures.

Rett syndrome may be misdiagnosed as autism, cerebral palsy, Angelman syndrome, or non-specific developmental delay.

Boys very rarely have Rett syndrome, but it is possible. The reason for this is explained more in the  Genetics of Rett Syndrome section.

Boys who have a change in the MECP2 gene usually have such serious brain disease that they don't survive past one to two years old.