Rett syndrome is an inherited disorder that affects only females. The syndrome causes mental retardation and developmental degeneration.
Causes, incidence, and risk factors
Rett Syndrome is a severe progressive neurological disorder that causes marked developmental regression, especially in the areas of expressive language and hand use. It occurs only in girls. The gene associated with this disorder was recently identified on the X-chromosome. This gene encodes methl-CpG-binding protein 2 (MeCP2), which regulates synthesis (transcription) of various other proteins. Synthesis of incorrect proteins, due to mutations in the gene, causes damage in the maturing brain. The severity of the disease is linked to specific types of mutation. Rett Syndrome has an estimated prevalence of seven to ten cases per 100,000 females. Females have two X chromosomes, so even when one has this significant mutation, the other X chromosome provides enough normal protein for the child to survive. Males conceived with this mutation are miscarried (spontaneously aborted) during pregnancy because they do not have a second X chromosome to compensate for the problem. Most cases (99.5%) are due to spontaneous mutations, rather than inheritance. However, the incidence of familial cases is higher than would be expected by chance, so there may be an inherited factor involved.
Signs and tests
Chromosomal analysis may now be used to search for the gene mutation that causes Rett Syndrome. Recent studies have now shown that a mutation of MeCP2 gene can be found in 75% of girls with Rett Syndrome. Earlier studies, which indicated that a smaller percentage of those with Rett Syndrome had the mutation, did not look for as full of an array of mutations.
Expectations (prognosis)
Disease progression stabilizes in many patients once they reach adolescence. The seizures may subside and hand use may improve. However, all of the women still have profound mental retardation. Discovery of the gene that causes Rett Syndrome will help in understanding the disease.
Complications
The girl can become totally unable to care for herself.
Calling your health care provider
Call your health care provider if you have any concerns about your child's development, if you notice a lack of normal development with motor or language skills in a child, or if there are associated disorders that need treatment.