Rett syndrome

Rett syndrome is a rare, severe, ‘girls only’ form of autism. It's usually discovered in the first two years of life, and a child's diagnosis with Rett syndrome can feel overwhelming. Although there's no cure, early identification and treatment may help girls and families who are affected by Rett syndrome.

Rett syndrome: Who's affected

Rett syndrome is an autism spectrum disorder that affects girls almost exclusively. It's rare -- only about one in 10,000 to 15,000 girls will develop Rett syndrome.

In most cases of Rett syndrome, a little girl develops normally in early life. Between six and 18 months of age, though, changes in the normal patterns of mental and social development begin.

Rett syndrome: Symptoms and signs

Although it's not always detected, a slowing of head growth is one of the first events in Rett syndrome. Loss of muscle tone is also an initial symptom. Soon, the little girl loses any purposeful use of her hands. Instead, she habitually wrings or rubs her hands together.

Around one to four years of age, social and language skills deteriorate in girls with Rett syndrome. A girl with Rett syndrome stops talking. She develops extreme social anxiety and withdrawal or disinterest in other people.

Rett syndrome also causes problems with muscles and coordination. Walking becomes awkward as girls develop a jerky, stiff-legged gait. A girl with Rett syndrome may also have uncoordinated breathing and seizures.

Causes of Rett syndrome

Most children with Rett syndrome have a mutation in a particular gene on the X chromosome. Exactly what this gene does, or how its mutation leads to Rett syndrome, isn't clear. It's believed that the single gene may influence many other genes involved in development.

Although Rett syndrome seems to be genetic, the faulty gene is almost never inherited from parents. Rather, it's a chance mutation that happens in the girl's own DNA. No Rett syndrome risk factors have been identified, other than being female. There is no known method for prevention of Rett syndrome.

When boys develop the Rett syndrome mutation, they die shortly after birth. Because boys have only one X chromosome (instead of the two girls have), the disease is more serious, and quickly fatal.

How is Rett syndrome diagnosed?

A diagnosis of Rett syndrome is based on a girl's pattern of symptoms and behaviour. The diagnosis can be made on these observations alone. Discussions between a doctor and a girl's parents will help determine important details, such as when symptoms started.

Genetic testing can help confirm the diagnosis in 80% of girls with suspected Rett syndrome. It's possible that genetic testing can help predict severity.