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.
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.
The seizures may be of various types including generalised convulsive (tonic-clonic) seizures, absences (where the child goes blank), myoclonic (jerk) seizures and tonic seizures (where the child stiffens).
A particular type of seizure called 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, the medical name for which is an ‘arrhythmia’.
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.
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.
The electroencephalogram test (EEG), which measures electrical activity in the brain, may show features which suggest Rett syndrome even when epilepsy is not present, and therefore can be useful in diagnosis.
Brain scans are normal in children with Rett syndrome.
Treatment of this condition can be very difficult. Anti-epileptic drugs that are often used include sodium valproate (Epilim), lamotrigine (Lamictal), carbamazepine (Tegretol, Tegretol Retard) and clobazam (Frisium). Other medications, including piracetam (Nootropil) may help to control seizures in some cases.
The seizures usually become less of a problem in adolescence and early adult life but only occasionally will the seizures stop completely.
With Rett syndrome there is usually increasing difficulty with walking and they may eventually not be able to walk. Many older children and teenagers will need special attention to prevent scoliosis (bending or curvature of the spine).
Feeding may also be a problem, particularly in early childhood and some children will need to be fed through a nasogastric tube (tube inserted through the nose) or even a feeding gastrostomy tube (tube inserted directly into the stomach).
The life-span of people with Rett syndrome is shortened, but most lives into early and middle adulthood. Unfortunately, most boys with Rett Syndrome will have a very shortened life-span.
Finally, all girls with Rett syndrome need complete care throughout their lives.
Rett Syndrome Association UK, Langham House West, Mill Street, Luton, LU1 2NA
tel: 01582 798910, fax: 01582 724129