Rett syndrome is a severe, genetic disorder that affects the way the brain develops. Occurring almost exclusively in girls, Rett syndrome produces symptoms similar to those of autism.

Most babies with Rett syndrome develop normally at first, but their progress often slows by the time they reach 18 months of age. Over time, children with Rett syndrome have increasing problems with motor function that may affect their ability to use their hands, speak, walk, chew and even breathe.

No cure exists for Rett syndrome. Treatment focuses on improving movement and communication and providing care and support for affected children and their families.

Symptoms of Rett syndrome vary from child to child. Some babies show signs of the disorder from birth with no period of normal development. Others have milder symptoms and may retain the ability to speak. And some children have seizures along with other symptoms of Rett syndrome.

Rett syndrome is commonly divided into four stages:

• Stage I. Signs and symptoms are subtle and easily overlooked during the first stage of Rett syndrome, which starts between 6 months and 18 months of age. Babies in this stage of Rett syndrome may show less eye contact and start to lose interest in toys. They may also have delays in sitting or crawling.
• Stage II. Starting between ages 1 and 4 years, children with Rett syndrome gradually lose the ability to speak and to use their hands purposefully. Repetitive, purposeless hand movements — wringing, washing, clapping or tapping — begin during this stage. Some children with Rett syndrome hold their breath or hyperventilate and may scream or cry without provocation. It's often difficult for them to initiate movement. Slowing of head growth usually is noted during this stage.
• Stage III. The third stage is a plateau that usually begins between the ages of 2 and 10 years and can last for years. Although problems with mobility continue, behavior may improve. Children in this stage often cry less, aren't as irritable, and may show an improvement in alertness, attention span and nonverbal communication skills. Many people with Rett syndrome remain in stage III for the rest of their lives.
• Stage IV. The last stage is marked by reduced mobility, muscle weakness and scoliosis — an abnormal curvature of the spine. Understanding, communication and hand skills generally don't decline further during this stage. In fact, repetitive hand movements may decrease. Although sudden death in sleep can occur, most people with Rett syndrome live into their 40s or 50s. They usually need care and assistance throughout life.

When to see a doctor
Because symptoms of Rett syndrome can be subtle in the early stages, parents should be alert for changes in a child's behavior, especially lack of eye contact or loss of interest in normal play. If you notice these signs, consult your child's doctor right away.

Most cases of Rett syndrome are caused by mutations in the MECP2 gene, which is involved in making a protein essential for normal brain development. The MECP2 gene is situated on the X chromosome — one of two chromosomes that determine a person's sex.

Girls have two X chromosomes in every cell. Because a cell needs only one working copy of the gene, each cell automatically inactivates one of its two X chromosomes. The more cells that have the mutated gene inactivated, the less severe the symptoms of Rett syndrome will be.

About 20 percent of girls with Rett syndrome don't have a typical MECP2 mutation. Researchers think that these children may have mutations in a different part of the gene or in genes that haven't yet been identified.

Rett syndrome in boys
The story is very different for most boys. Unlike girls, boys normally have one Y and one X chromosome in each cell. Because the single X chromosome can't be inactivated, boys who have the genetic mutation that causes Rett syndrome aren't protected from the devastating effects of the disease. Most of them die before birth or in early infancy.

A few boys have an extra X chromosome in many or all of their cells and may survive if they have an MECP2 mutation. A very small number of boys have mutations in the MECP2 gene in a few cells. They, too, are likely to live to adulthood.

What causes the genetic mutation?
Rett syndrome is a genetic disorder, but in only a few cases is it inherited. Instead, the genetic mutation that causes the disease occurs randomly and spontaneously — often when sperm are formed and occasionally after conception.

Rett syndrome is rare, occurring in one out of every 10,000 to 20,000 births. It affects children of all races and nationalities. The only known risk factor is having genetic mutations known to cause the disease.

Most children with Rett syndrome have trouble eating, so they often are shorter and weigh less than other children their age. To maintain proper nutrition, some children need to be fed through tubes placed in their noses or stomachs. Constipation can be a severe and chronic problem.

Other common problems include:

• Seizures
• Unusual heart rhythms (cardiac dysrhythmias)
• Bone fractures
• Scoliosis (abnormal curvature of the spine)

Your child's doctor will look for developmental problems at regular checkups. If he or she shows any symptoms of Rett syndrome, your child will likely be referred to a pediatric neurologist or developmental pediatrician for a thorough clinical evaluation.

It's a good idea to be well-prepared for your child's appointment. Here's some information that may help you get ready.

What you can do

• Write down all the changes that you and others have observed in your child's behavior. The specialist will examine your child carefully and monitor growth and development, but your daily observations are also extremely important.
• Make a list of any medications, including vitamins, herbs and over-the-counter medicines that your child is taking.
• If possible, bring a family member or friend with you. This is important not just to help you remember information but also for emotional support.
• Write down questions that you want to ask your child's doctor. Don't be afraid to ask questions or to speak up when you don't understand something that's said. And if you run out of time, ask to speak with a nurse or physician assistant, or leave a message for the doctor.

Questions to ask might include:

• Why do you think my child does (or doesn't) have Rett syndrome?
• Is there a way to confirm the diagnosis?
• If my child does have Rett syndrome, is there a way to tell how severe it is?
• What changes can I expect to see in my child over time?
• Can I take care of my child at home or will I need to look for outside care?
• What kind of special therapies do children with Rett syndrome need?
• How much and what kinds of regular medical care will my child need?
• What kind of support is available to families of children with Rett syndrome?
• How can I learn more about this disorder?

Diagnosing Rett syndrome involves careful observation of your child's growth and development and a complete medical and family history.

Your child may also have certain tests to help rule out conditions that cause similar symptoms. These range from simple blood and urine tests to nerve conduction studies, which measure the speed of impulses through a nerve, and imaging tests such as magnetic resonance imaging (MRI) or computerized tomography (CT) scans. Your child is not likely to have all of these tests, and your doctor will inform you fully of what is involved in any tests your child does have.

Once the evaluation is complete, your doctor will use specific guidelines to help diagnose Rett syndrome.

A diagnosis of the disorder requires the following criteria:

• Apparently normal development until at least the age of 6 months
• Normal head circumference at birth, followed by a slowing of the rate of head growth between the ages of 3 months and 4 years
• Severely impaired language skills
• Repetitive hand movements
• Shaking of the torso
• Toe walking or an unsteady, wide-based gait

In addition to these core (essential) symptoms, children with Rett syndrome may have other problems, such as seizures, scoliosis, trouble sleeping, irritability, poor circulation and constipation. Unless the core symptoms are present, however, your child does not have Rett syndrome.

Genetic testing
A genetic test can confirm a diagnosis of Rett syndrome. The test requires drawing a small amount of blood from a vein in your child's arm. The blood draw takes just a few minutes and shouldn't be too uncomfortable, though there may be a prick when the needle is inserted.

The same test can help detect MECP2 mutations in female relatives of children with Rett syndrome as well as in unborn children.

Treating Rett syndrome requires a multidisciplinary approach, including regular medical care; physical, occupational and speech therapy; and academic, social and vocational services. The need for this level of care and support doesn't end as children become older and is usually necessary throughout life.

Treatments that can help children and adults with Rett syndrome include:

• Medications. Though medications can't cure Rett syndrome, they may help control some of the symptoms associated with the disorder, such as seizures and muscle stiffness.
• Physical and speech therapy. Physical therapy and the use of braces or casts can help children who have scoliosis. In some cases, physical therapy can also help maintain walking skills, balance and flexibility, while occupational therapy may improve purposeful use of the hands. If repetitive arm and hand movement is a problem, splints that restrict elbow or wrist motion may be helpful. Children with Rett syndrome may show improvements in their overall functioning when their habitual movement is disrupted. Speech therapy can help improve a child's life by teaching nonverbal ways of communicating.
• Nutritional support. Proper nutrition is extremely important for both normal growth and for improved mental and social functioning. Some children with Rett syndrome may respond to a high-fat, high-calorie diet. Others may need to be fed through a tube placed in the nose (nasogastric tube) or directly in the stomach.

Because Rett syndrome is a severe and incurable disorder, parents understandably search for treatments that will improve their child's symptoms and quality of life. Many alternative treatments have been tried, including acupuncture, chiropractic and myofascial release, a massage therapy that helps loosen stiff muscles and joints.

Unfortunately, many of these approaches haven't been well studied, though there is some evidence that a specific type of acupuncture may affect brain function in autistic children and improve mild scoliosis.

Other alternative therapies that have been used in children with Rett's syndrome include:

• Animal-assisted therapy, including horseback riding and swimming with dolphins
• Auditory integration training, which uses certain sound frequencies to treat speech and language problems
• Music therapy
• Hydrotherapy (swimming or moving in water)
• Yoga

There is no scientific evidence that these approaches are effective, though some parents who have used them report good results. If you are interested in learning more, check the Internet or contact the International Rett Syndrome Association.

Children with Rett syndrome need help with most daily tasks, such as eating, walking and using the bathroom. This constant care can be exhausting and stressful for families. It is natural to feel overwhelmed at times. Talking about your problems can help relieve your feelings of stress. Arrange for outside help to ease your load.

Many families affected by Rett syndrome care for their children at home, often with the help of outside caregivers who can give parents a break. Other families choose residential care, especially when their children become adults.

Each family and each child with Rett syndrome is different. But connecting with other families facing the same problems can help you feel less alone. Online support and information are available from the International Rett Syndrome Association.

There is no known way to prevent Rett syndrome. In the vast majority of cases, the genetic mutation that causes the disorder occurs spontaneously. Even so, people who have a child or other family member with Rett syndrome may want to discuss genetic testing with their doctor.