A neurodevelopmental disorder affecting girls almost exclusively, Rett Syndrome is characterized by the loss of previously acquired skills, including purposeful hand movements and the ability to communicate. Further signs of the condition include the slowing of head growth, autistic-like behaviors, seizures, disorganized breathing patterns, and impairment of movements and coordination required for walking. In fact, studies have revealed that the brains of those with Rett Syndrome are 12-33 percent smaller than normal with about half the normal number of synapses, though no obvious malformations or gross abnormalities exist, cites the International Rett Syndrome Association, Clinton, Md.
Rett Syndrome is caused by the mutation of a gene known as MECP2, located on the X chromosome and discovered as recently as 1999. The condition, originally described by Dr. Andreas Rett of Austria in 1966, was relatively unknown until the mid-1980s. While gene mutations happen often, this particular mutation creates a shortage or absence of the MECP2 protein required to regulate genes that “affect or control normal development of selected regions of the brain responsible for sensory, emotional, motor and autonomic function during the critical period of infancy when important milestones are expected to be achieved,” cites the International Rett Syndrome Association. The MECP2 gene is not required for early brain development, but is essential for the maintenance of maturing brain cells, according to the Rett Syndrome Research Foundation, Cincinnati. For this reason, a child with Rett Syndrome may appear to develop normally at first.
The onset of symptoms typically begins between the ages of 6 and 18 months. While the condition is a spectrum disease — severity varies widely — the typical stages include the early onset stage (6-18 months), followed by the rapid destructive stage (1 to 4 years), then the plateau stage (preschool to adulthood) and finally the late motor deterioration stage.
Though there is no cure for the condition, Rett Syndrome is not fatal, and many women with the condition mature into adulthood. Average life expectancy may exceed 47 years, with death occurring most frequently from sudden, unexplained causes or secondary to pneumonia. The worldwide prevalence of the disorder has been estimated to fall somewhere between 1 in 10,000 to 1 in 23,000 female births, according to the International Rett Syndrome Association. Rett Syndrome can be misdiagnosed as autism, cerebral palsy or nonspecific developmental delay — so many more may be currently undiagnosed.
Any pregnancy may result in a child with Rett Syndrome. No familial links exist. While the condition must be diagnosed by ruling out conditions that look similar — such as Angelman Syndrome and the infantile form of neuronal ceroid lipofuscinosis — a blood test can prove the gene mutation.
The inability to perform motor functions is indeed the most disabling feature of Rett Syndrome and affects every body movement, cites the National Institute of Neurological Disorders and Stroke, Bethesda, Md. Because severity may vary, some girls begin walking independently immediately, but others show significant delay or complete inability to walk. Mobility eventually decreases with age.
Treatment is symptomatic and often involves occupational therapy, physical therapy and hydrotherapy to prolong mobility. Some drug therapies, such as Bromocriptine (Parlodel), have showed initial improvements in trials, according to the International Rett Syndrome Association, but further research is needed.
A spectrum of mobility equipment may be used to help manage the condition, including walkers, gait trainers, wheelchairs, orthotic devices, lifts and ramps, standers, seating and positioning devices, such as solid seats with a solid backs for upright, level pelvic alignment and lateral supports to prevent leaning or slumping, and bath safety equipment.
It is impossible to determine the level of cognitive ability because the forms of testing require either movement or speech — two abilities someone with Rett Syndrome does not have. Unlike those with autism, however, people with Rett Syndrome typically respond well to emotional therapy and show a marked preference for people over objects. Assistive technology such as eyegaze systems can aid in communication. “The most important point to remember is that individuals with Rett may have lost their ability to speak, but they have not lost their desire to communicate,” says the Rett Syndrome Research Foundation.
Sources & Resources
National Institute of Neurological Disorders and Stroke (NINDS)
National Organization for Rare Disorders (NORD)
International Rett Syndrome Association
Rett Syndrome Research Foundation (RSRF)