Rett Syndrome and Autism: How Are They Different and Similar?

Avoiding eye contact and hand-wringing are classic signs of autism spectrum disorder. But they’re also connected to a much rarer genetic condition called Rett syndrome. Autism and Rett syndrome can look like one another — but there are some key differences that help doctors diagnose each condition.

Rett syndrome can sometimes be misdiagnosed as regressive autism. Knowing the signs and symptoms of Rett syndrome and autism can guide you when talking to your child’s pediatrician. Genetic testing and screenings with a trained specialist can help them reach the right diagnosis.

Rett Syndrome Is Very Rare, While Autism Is More Common

Rett syndrome is a rare condition that affects approximately 1 in every 10,000 girls in the U.S. by age 12, according to the National Organization for Rare Disorders (NORD). On the other hand, autism is much more common. The U.S. Centers for Disease Control and Prevention (CDC) estimates that 1 in every 31 children is affected by autism by age 8.

Males aren’t diagnosed with Rett syndrome nearly as often as females, according to NORD. This is because the syndrome is caused by certain gene changes that, in males, usually result in stillbirth or miscarriage. That said, Rett syndrome can still occur in living males in rare cases.

Rett Syndrome and Autism Have Different Causes

Over 90 percent of Rett syndrome cases develop from a mutation (change) in the MECP2 gene. Researchers have found over 200 different mutations that play a role in Rett syndrome. Nearly every child with Rett syndrome randomly develops a mutation. These mutations are not usually passed down from parents.

The causes of autism are still being researched. Many researchers believe it’s a combination of inherited and environmental factors. Cleveland Clinic notes that genetics may play a role in autism. However, it’s not as straightforward as a single gene change in Rett syndrome. Researchers think that many gene variations — small changes in DNA — might be linked to autism.

Rett Syndrome and Autism Are Diagnosed Differently

Doctors use different tests to diagnose Rett syndrome and autism while ruling out other conditions. The exact screenings will depend on your child’s symptoms.

Your child’s pediatrician may collect a small blood sample for genetic testing. Rett syndrome is a genetic disorder caused by MECP2 mutations. A simple blood test lets them look for these changes. However, not everyone with an MECP2 mutation has Rett syndrome. Your pediatrician will also look at your child’s behavior and for other signs to make their diagnosis.

Healthcare professionals diagnose autism using different screening tools. These tools evaluate your child’s development and behaviors. Autism screening usually involves both the caregivers and professional observers collecting information about the child. You may work with a specialist — such as a neurodevelopmental pediatrician — to learn more about your child’s screening and diagnosis.

Rett Syndrome Affects the Entire Body, While Autism Typically Doesn’t

Rett syndrome and autism share some signs and symptoms — but there are some distinct differences. Since Rett syndrome is a genetic disorder, it affects the entire body. You may notice symptoms that don’t typically affect children with autism, such as:

• Breathing irregularities, like hyperventilation (breathing too fast), breath holding, and swallowing air
• Sleep problems, such as sleeping during the day and staying awake at night
• Apnea, or periods where your child stops breathing, especially when they’re sleeping
• Seizures related to epilepsy
• Issues with hand use and hand skills
• Teeth grinding
• Fits of screaming or crying
• Uncontrollable eye movements
• Smaller head growth, which affects brain development
• Scoliosis (atypical curvature in the spine)
• Muscle weakness and loss of coordination, causing problems with motor skills
• Irregular heartbeats, which raise the risk of life-threatening complications

Many people with Rett syndrome live into adulthood, but complications can lead to a shorter life expectancy.

Autism doesn’t usually affect as many of the body’s systems as Rett syndrome does. It’s common for children with autism to have digestive issues such as constipation, diarrhea, and stomach pain. Some research also shows that some children living with autism may have changes in their immune system. This can raise their risk of infections and other conditions in which their immune systems may damage healthy tissues.

The Severity of Symptoms Differs Between Rett Syndrome and Autism

Rett syndrome is a progressive neurological disorder — meaning symptoms worsen over time. Doctors divide Rett syndrome into four stages:

• Stage 1 — Babies develop symptoms between 6 and 18 months. Early signs can include making less eye contact and delays in sitting and crawling.
• Stage 2 — Children between the ages of 1 and 4 can have coordination and movement problems, as well as worsening communication and social skills.
• Stage 3 — Symptoms plateau at this stage (ages 2 to 10) and can improve in some cases. Some children may have seizures at this stage.
• Stage 4 — After age 10, children tend to have muscle weakness, mobility problems, joint contractures (stiff joints), and scoliosis.

Many children with Rett syndrome develop intellectual disabilities that affect their ability to learn and understand. As they age, many adults with Rett syndrome need around-the-clock care and supervision.

Like Rett syndrome, autism usually develops during early childhood. However, autism doesn’t progress. Symptoms of autism mainly affect communication skills and social interactions. Many adults with autism can lead fairly typical lives, though they may need additional support with finding employment, accessing resources, and getting accommodations as needed.

Rett Syndrome and Autism Share Some Signs and Symptoms

Rett syndrome and autism share many of the same symptoms — so much so that doctors can misdiagnose Rett syndrome as regressive autism. Both conditions start appearing around the same age, usually before or near a child’s first birthday or in early childhood. Some children may hit their developmental milestones as expected, then start showing signs of autism at around 18 to 24 months old.

Repetitive Hand Movements

One of the most commonly shared symptoms between Rett syndrome and autism is repetitive hand movements. Children with either condition may show signs like:

• Hand-wringing
• Rubbing
• Clapping
• Squeezing

One study found that children with Rett syndrome and autism tend to move their hands in different patterns. Those with Rett syndrome would make repetitive movements toward their mouths and the centers of their bodies. Children with autism would hold objects and move less often.

Decline in Communication Skills and Social Interactions

Rett syndrome and autism also cause a similar decline in communication and social skills. Signs to look out for with both conditions include:

• Difficulty making eye contact
• Loss of interest in conversation or playing with toys
• Difficulty communicating with speech
• Less interest in attention from parents or caregivers

Some children with Rett syndrome or autism show signs of typical development until around 2 years of age. Changes and regression in skills may be a sign of either condition. It’s important to note that there’s no specific timeline for when the symptoms of Rett syndrome and autism develop. Each child is unique, and their experience may look different from another child’s.

Talk to Your Pediatrician About Rett Syndrome and Autism

If your child has started showing signs of developmental delays or behavioral changes, talk to your pediatrician. They can recommend tests to help clarify what’s happening with your child. They may also refer you to a specialist trained to assess children with developmental disorders. Together, your healthcare team will help you determine the next best steps forward for your child’s health and well-being.

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