Rett syndrome is classified under the Pervasive Developmental Disorders, but Rett syndrome has identifiable physical differences such as reduced muscle tone (causing the child to seem "floppy") and stereotyped hand movements such as wringing and waving.
Rett syndrome is a neurodevelopmental disorder that causes severe disability in young children, mostly girls. After a period of relatively normal development, children with Rett syndrome lose skills such as language, play and hand use. The hallmark of the disorder is the development of midline hand wringing or patting movements that may be constant while the child is awake. Head growth, which is a reflection of brain growth, slows down in the 1st and 2nd years of life. Rett syndrome is caused by a mutation (unfavorable change in DNA) in a gene called MECP2 that is on the X chromosome. The mutation itself causes Rett syndrome, as well as other developmental disorders. The diagnosis of Rett syndrome still rests on clinical characteristics. Many girls with Rett syndrome have received a diagnosis of autism during their period of regression, which is why Rett syndrome is currently classified as a "pervasive developmental disorder".
A routine chromosome analysis (karyotype) will not identify the Rett syndrome mutation. A specific probe for the MECP2 gene must be ordered.
Generally, Rett syndrome is divided into four stages, and depending on a particular stage and its severity, the signs and symptoms vary.
- Stage I: Generally, stage I of the Rett syndrome commences to affect the child when she is around 6 months to 18 month old. The signs and symptoms are rather very mild and they are mostly overlooked. The child shows less eye contact and does not show much interest in toys. The development of sitting and crawling also get delayed.
- Stage II: Stage II sets in at around 1 to 4 years, and the child affected "lose the ability to speak and to use their hands purposefully." Unusual hand movements like repetitive, purposeless hand movements — wringing, washing, clapping or tapping" start during the stage II. The breathing becomes irregular; the child may sometimes hold breath or engage in hyperventilating. Screaming or crying without any apparent provocation may happen. They may scream or cry without provocation. It's often difficult for them to initiate movement.
- Stage III: This stage begins between the ages 2 and 10 years and may last for several years, even for the remainder of life. Mobility of the child affected may continue though behavior improves. Crying and displaying irritation may decline, and nonverbal communication skills also improve.
- Stage IV: Although understanding, communication skills and hand skills do not decline during this phase, stage IV is marked by "reduced mobility, muscle weakness and scoliosis — an abnormal curvature of the spine." In some cases, sudden death may occur during sleep, most of the women survive till 40s and 50s.
Generally, Rett syndrome manifests itself in four stages:
- Early Onset Phase: It is the first stage. During this phase, normal development stops or gets stalled.
- Rapid Destructive Phase: This is the second phase. During this phase, a rapid regression of already acquired skills get regressed. Meaningful hand movements and speech abilities are first to be lost.
- Plateau Phase: In the third stage, the plateau phase, regression slows and other related complications improves a little. Most of the persons with Rett syndrome pass their years in this phase.
- Late Motor Deterioration Phase: In this phase, the person becomes stiff and/ or lose muscle tone.
One of the common complications of Rett syndrome include trouble with the eating, and hence the girls affected with it are generally shorter and weigh less than the normal weight. Other complications of Rett syndrome include:
- Epilepsy: This is a condition of temporary abnormal electrical discharges in the brain, which can produce a temporary loss of consciousness (a "blackout"), a body convulsion, unusual movements, or staring spells.
- Cardiac arrhythmias: This describes a number of conditions which indicate that the electrical activity of the heart is irregular - faster or slower than the normal electrical activity of the heart.
- Bone fractures: It is a condition in which a bone becomes broken.
- Abnormal curvature of the spine: In medical term, this condition is called Scoliosis. It is a condition that "that involves complex lateral and rotational curvature and deformity of the spine".
Currently there is not known cure to treat Rett syndrome though girls affected with this disorder can be treated to reduce the signs and symptoms associated with this disorder. Such treatments are aimed to slow the loss of already acquired skills and increase the level of communication (including speech) and social contact. Generally, a team approach to the treatment is preferable as health care personnel from diverse backgrounds pull together their expertise to treat Rett syndrome. The role of close family members and family friends is also crucial for a better result. Health care personnel may include professionals from the fields of physical therapy, occupational therapy, and speech-language therapy. In some case, medications to reduce complications of constipation or complications related to heart, and surgery to set in order spine curvature are also resorted to to treat Rett syndrome.