What is Rett syndrome?
Early in childhood, affected girls lose purposeful use of their hands and begin making repeated hand wringing, washing, or clapping motions. They tend to grow more slowly than other children and have a small head size (microcephaly).
Other signs and symptoms can include breathing abnormalities, seizures, an abnormal curvature of the spine (scoliosis), and sleep disturbances.
Researchers have described several variants of Rett syndrome with overlapping signs and symptoms. The atypical forms of this disorder range from a mild type, in which speech is preserved, to a very severe type that has no period of normal development. A form of Rett syndrome called the early-onset seizure variant has most of the characteristic features of classic Rett syndrome, but also causes seizures that begin in infancy.
How common is Rett syndrome?
Causes, incidence, and risk factors
Studies have linked many Rett syndrome cases to a defect in the methl-CpG-binding protein 2 (MeCP2) gene. This gene is on the X chromosome. Females have two X chromosomes, so even when one has this significant defect, the other X chromosome is normal enough for the child to survive.
Males born with this defective gene do not have a second X chromosome to make up for the problem.
Therefore, the defect usually results in miscarriage, stillbirth, or very early death.
Symptoms may include:
- Apraxia [verbal apraxia or dyspraxia, is a speech disorder in which a person has trouble saying what he or she wants to say correctly and consistently. It is not due to weakness or paralysis of the speech muscles (the muscles of the face, tongue, and lips). The severity of apraxia of speech can range from mild to severe.]
- Breathing problems -- problems tend to get worse with stress; breathing is usually normal during sleep and abnormal while awake
- Change in development
- Excessive saliva and drooling
- Floppy arms and legs -- frequently the first sign
- Intellectual disabilities and learning difficulties (assessing cognitive skills in those with Rett syndrome, however, is difficult because of the speech and hand motion abnormalities)
- Shaky, unsteady, or stiff gait; or toe walking
- Slowing head growth beginning at approximately 5 - 6 months of age
- Loss of normal sleep patterns
- Loss of purposeful hand movements; for example, the grasp used to pick up small objects is replaced by repetitive hand motions like hand wringing or constant placement of hands in mouth
- Loss of social engagement
- Ongoing, severe constipation and gastroesophageal reflux (GERD)
- Poor circulation that can lead to cold and bluish arms and legs
- Severe language development problems
Problems in breathing pattern may be the most upsetting and difficult symptom for parents to watch. Why they happen and what to do about them is not well understood. Most experts in Rett syndrome recommend that parents remain calm through an episode of irregular breathing like breath holding. It may help to remind yourself that normal breathing always returns and that your child will become used to the abnormal breathing pattern.
Signs and tests
There are several different types of Rett syndrome:
- Classical (meets the diagnostic criteria)
- Provisional (some symptoms appear between ages 1 and 3)
- It begins early (soon after birth) or late (beyond 18 months of age, sometimes as late as 3 or 4 years old)
- Speech and hand skill problems are mild
- It is appears in a boy (very rare)
- Assistance with feeding and diapering
- Methods to treat constipation and GERD
- Physical therapy to help prevent the hands from contracting
- Weight bearing exercises for those with scoliosis
Medications such as carbamazepine may be used to treat seizures. Other medications or supplements that have been used or studied include:
Developmental regression or delays vary. Usually, a child with Rett syndrome sits up properly but may not crawl. For those who do crawl, many do so by scooting on their tummy without using their hands.
Similarly, some children walk independently within the normal age range, while others are delayed, don't learn to walk independently at all, or don't learn to walk until late childhood or early adolescence. For those children who do learn to walk at the normal time, some keep that ability for their lifetime, while other children lose the skill.
Life expectancies are not well studied, although survival at least until the mid-20s is likely. The average life expectancy of a girl with Rett syndrome may be mid-40s. Death is often related to seizure, aspiration pneumonia, malnutrition, and accidents.
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