Rett syndrome
Incidence
Rett syndrome is a sporadic clinical syndrome usually restricted to girls. Rett syndrome is a neurodevelopmental disorder affecting one in 10,000 female. Recently found related to a defect in the MECP2 gene on the X chromosome. This syndrome happens in about one in every 10,000-12,000 girls. It may rarely affect boys. Boys are always affected far more severely than girls. The cause is due to a genetic abnormality, called a ‘mutation’. This abnormality or mutation is usually found on one of the sex chromosomes – the X chromosome. The most common mutation is called the MECP2 mutation. A different and much less commonly found genetic mutation is nearly always seen in those children with Rett syndrome who have a very severe type of epilepsy.
Clinical Characteristics
Girls with Rett Syndrome may show normal development for the first six or more months of their life. Then between six months and 30 months of age (often between six-18 months), their development slows down and may even go backwards. They become less interested in play, lose the ability to speak and may become irritable and scream for no obvious reason. They stop using their hands purposefully and they may, instead, begin to move their hands in a repetitive way, often with hand-wringing or hand-washing movements. Epilepsy eventually happens in about 70 per cent of those children. It usually begins after the age of two years but may begin in the first year of life. It is considered an epileptic syndrome. The seizures may be of various types including generalised convulsive (tonic-clonic) seizures, absences, myoclonic seizures and tonic seizures. Infantile spasms may also happen and this is usually in the first year of life in girls with the less common genetic mutation. Often more than one seizure type is present.
Frequently, girls with Rett syndrome have periods of rapid or slow breathing. These periods are sometimes associated with faints, which can be mistaken for epileptic seizures. Some girls will also have a disturbance of their heart rate and rhythm (arrhythmias).
When boys are affected, the epileptic seizures nearly always start within the first few weeks or months of life and are often extremely difficult to treat.
In summary, Rett syndrome usually have its onset is between 6 to 18 months. They have prior normal development. Begin as an arrest of motor and mental activities, with progressive microcephaly and autistic behavior. There is loss of purposeful use of hands, with manual stereotypies like washing and rubbing hands. Hyperventilation episodes. There are frequent seizures, usually generalized. There is apraxia of gait. There is loss of gait ability before age 10 years. Girls with Rett syndrome appear to develop normally until six to 18 months of age. They then enter a period of regression, losing acquired speech and hand skills, and develop seizures, repetitive hand-wringing or hand-washing movements, irregular breathing and motor-control problems. The girls can live to adulthood, but most never regain the ability to use their hands or to speak.
Precipitants
no
Provocation Tests
no
Diagnostic Procedures
Clinical diagnosis, All lab tests are normal. Lab work is NORMAL or LOW: 5-methyl-THF (CSF). The most common mutation is called the MECP2 mutation, and is investigated in blood. The discovery of the genetic mutation in Rett syndrome has made it much easier to diagnose the condition. However, it is obviously important for doctors to think about the condition in the first place so that the blood test can then be done to look for the genetic mutation. This common mutation is found in about 80 per cent (eight out of every 10) girls with Rett syndrome. Before the genetic mutation was discovered, the diagnosis of Rett syndrome was not usually made until girls were aged three, four or even six years of age.