An Introduction to Rett Syndrome
What separates Rett syndrome from the other Pervasive Developmental Disorders is that it almost exclusively affects girls, whereas Autistic Disorder affects boys at a much higher rate than girls.
Worldwide Rett Syndrome affects 1 in every 10,000 to 15,000 females of all races and ethnicity. Prenatal testing is possible for families who have had a child born with Rett, but since the chances of developing Rett is so low, the chances of a family having two children born with Rett is less than 1%. Most boys born with the genes thought to be responsible for Rett often die shortly after birth. Because Rett syndrome is thought to be caused by a mutation to the X chromosome, girls are thought to be more able to compensate for the mutation because they have two X chromosomes where boys only have one and aren’t able to compensate.
In Rett Syndrome, similar to Asperger’s, there is normal early development and then a slowing of development, distinctive hand movements, lack of purposeful use of hands, and slowed head and brain growth. Problems walking, seizures and intellectual disability are usually also present. This disorder was first described by Dr. Andreas Rett, an Austrian physician in 1966, but it wasn’t until later in 1983 that it was recognized as a disorder after an article about it was written by Swedish researcher Dr. Bengt Hagbeg.
Like all of the Pervasive Developmental Disorders, the severity of symptoms in Rett varies from child to child, but they all start with relatively normal development, although loss of muscle tone (hypotonia), jerkiness in limb movements and difficulty feeding are often noticeable even in infancy. Gradually more apparent physical and mental symptoms become apparent such as the inability to talk and loss of purposefully movement of hands which is followed by compulsive hand movements such as wringing and washing. Other symptoms such as problems walking, crawling and lack of eye contact may also be early signs. This period of regression is often sudden. The inability to perform motor functions (Apraxia) is one of the most severe disabilities of Rett syndrome, it effects body movement, eye gaze and speech.
Early stages of Rett syndrome often resemble Autistic disorder or one of the other Pervasive Developmental Disorders. Some symptoms may also include walking on toes, awkward gait, difficulty chewing, teeth grinding, slowed growth, sleep problems, breathing problems, air swallowing, cognitive disabilities and apnea (holding breath)..
Rett is typically diagnosed by a developmental pediatrician, pediatric neurologist or clinical neurologist using many of the same neurological, physical and psychological assessments used to diagnose the other Pervasive Developmental Disorders with the inclusion of genetic testing to look for the MECP2 mutation on the child’s X chromosome.
The Diagnostic and Statistical Manual of Mental Disorders also has these criteria for diagnosing Rett Disorder.
- All of the following:
- apparently normal prenatal and perinatal development
- apparently normal psychomotor development through the first 5 months after birth
- normal head circumference at birth
- Onset of all of the following after the period of normal development:
- deceleration of head growth between ages 5 and 48 months
- loss of previously acquired purposeful hand skills between ages 5 and 30 months with the subsequent development of stereotyped hand movements (i.e., hand-wringing or hand washing)
- loss of social engagement early in the course (although often social interaction develops later)
- appearance of poorly coordinated gait or trunk movements
- severely impaired expressive and receptive language development with severe psychomotor retardation
According to research, nearly all cases of Rett syndrome are due to a mutation in the metyl CpG binding protein 2 (MECP2) gene. The gene was discovered in 1999 and controls many other genes. It may also be responsible for some of the other Pervasive Developmental Disorders. This gene is needed for brain development and helps other genes increase or decrease their own unique expressions and proteins. This genes malfunction causes other genes to become abnormal. The puzzling thing is, not everyone with MECP2 mutation has Rett syndrome, so other genetic mutations are also thought to be responsible and research is ongoing. Rett syndrome is not thought to be genetic. Only about 1% of Rett syndrome cases are thought to be inherited, which means that in the overwhelming majority of cases, the gene mutations are random.
Just like all the other Pervasive Developmental Disorders, there is no cure for Rett Syndrome and treatment is pretty similar including medication and therapy to help control and minimize many of the disabling features of Rett syndrome.
Although Rett syndrome can be very disabling, many people with Rett live to be in their 40’s and 50’s and perhaps even longer .
International Rett Syndrome Foundation: www.rettsyndrome.org
National Institute of Child Health and Human Development (NICHD): www.nichd.nih.gov
Office of Rare Diseases: www.rarediseases.info.nih.gov
Rett Syndrome Research Trust: www.rsrt.org