How Rare Is Rett Syndrome? Prevalence and Statistics

Rett syndrome is a rare genetic condition that affects motor skills, development, and communication skills. According to the International Rett Syndrome Foundation, it mainly impacts girls. This neurodevelopmental disorder (a condition that affects the developing brain) usually appears after a period of typical early growth, which can make a diagnosis especially confusing. Because most people haven’t heard of Rett syndrome before, many parents and caregivers wonder just how rare it is. Below are key statistics about the prevalence of Rett syndrome and how it affects people’s lives.

Rett Syndrome Affects About 1 in 10,000 to 20,000 Females Worldwide

Rett syndrome is considered a rare disease. Most estimates suggest it occurs in roughly 5 to 10 out of every 100,000 females, according to Systematic Reviews. This rarity means many healthcare providers may see only a few cases, or none at all, during their entire careers.

Rett Syndrome Is Much Less Common in Males

Rett syndrome is extremely rare in males, though we don’t have reliable statistics about just how rare it is. According to the journal Cureus, when this genetic disorder does occur in males, it’s often associated with more severe symptoms. Some males with Rett are stillborn or die early in infancy. Many affected boys have other genetic differences such as mosaicism (a mutation, or change, in only some cells), milder variants (less severe mutations), or conditions like Klinefelter syndrome (an extra X chromosome) that allow them to survive beyond infancy.

Around 90 Percent of Classic Rett Syndrome Is Caused by MECP2 Mutations

The majority of children with classic Rett syndrome have a mutation in the MECP2 gene. This gene plays a key role in brain development and function. These mutations usually happen spontaneously, meaning they aren’t passed down from parent to child. MECP2 gene mutations are not caused by anything that parents did or didn’t do.

Rett Symptoms Usually Begin Between 6 and 18 Months of Age

Most children with Rett syndrome appear to develop typically for the first several months of life. Symptoms often begin between 6 and 18 months, when developmental progress slows or skills like speech and purposeful hand use are lost. This period is often called developmental regression.

There Are 4 Stages of Rett Syndrome

Stage 1 Rett syndrome begins with subtle symptoms like delays in crawling and making less eye contact. During stage 2, between 1 and 4 years of age, children rapidly lose skills they had. At stage 3, children hit a plateau in their developmental milestones and may start to experience seizures. In stage 4, usually after age 10, children usually experience reduced mobility and muscle weakness.

Epilepsy Affects 60 Percent to 80 Percent of People With Rett Syndrome

Seizures are one of the most common medical conditions seen in Rett syndrome. While some people are able to control their seizures, others may experience frequent or difficult-to-treat epilepsy. There are also some people with Rett syndrome who never develop seizures.

Nearly All Individuals With Rett Syndrome Have Language Impairment

Rett is known to cause differences in communication, which is why it’s commonly misdiagnosed as autism. While most children with Rett don’t use spoken language to communicate, many children find ways to communicate through eye gaze, facial expressions, or assistive technology.

Over 80 Percent of People With Rett Syndrome Experience Breathing Irregularities

Many children experience abnormal breathing patterns, such as breath-holding, hyperventilation, or air swallowing. These episodes often occur while awake and can be distressing for caregivers, even though they may improve with age.

Scoliosis Is Common Over Time

Scoliosis (atypical sideways curving of the spine) is common, especially as children grow older, largely due to decreased muscle tone. Regular monitoring by orthopedic specialists is important, and management may include physical therapy, bracing, or surgery in severe cases.

Growth Delays and Feeding Difficulties Are Common

Most children with Rett syndrome have trouble gaining weight and growing at a typical rate. Feeding challenges, including chewing and swallowing difficulties, are common and may require support from nutrition or feeding specialists.

Many People With Rett Syndrome Live Into Their 40s or Longer

In the past, Rett syndrome was thought to greatly reduce life expectancy. Now, life expectancy has improved significantly with better care. Today, many individuals live into adulthood and middle age, especially with good medical care, treatment interventions, and monitoring of complications.

Understanding the Numbers

While Rett syndrome is rare, these statistics show that families are not alone. Research continues to improve our understanding of the condition, leading to better diagnosis, treatment, and support.

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