The National Institute of Health defines Rett Syndrome as a neurodevelopmental disorder that affects girls almost exclusively. Nearly all cases are caused by a mutation that affects a gene containing instructions for the synthesis of a protein called methyl cytosine binding protein 2 (MeCP2), which is needed for brain development. Rett Syndrome “is characterized by normal early growth and development followed by a slowing of development, loss of purposeful use of the hands, distinctive hand movements, slowed brain and head growth, problems with walking, seizures, and intellectual disability.” The age of onset and the severity of symptoms vary per child.
Before symptoms are identified, a child seems to grow and develop normally. Stage I typically begins between six and 18 months of age, and there may be subtle abnormalities, such as loss of muscle tone, difficulty feeding, and jerkiness in limb movements, but these traits are not atypical in infants. Gradually, though, mental and physical symptoms appear. In the early stages of the disorder, children with Rett syndrome exhibit autistic-like behaviors. Initial symptoms may include problems crawling or walking and reduced eye contact. Stage II, or the rapid destructive stage, usually begins between the age of one and four years, and may last for weeks or months. The progression causes loss of purposeful use of the child’s hands followed by compulsive hand movements like wringing or clapping and loss of ability to speak. The period of regression is sometimes sudden. Stage III, or the “plateau or pseudo-stationary stage,” usually begins between ages two and 10 and can last for years. Motor problems and seizures are prominent during this stage, in which girls remain for most of their lives. However, there may be behavior improvements such as less irritability and crying, more interest in surroundings, as well as better attention span and communication skills. Stage IV, the late motor deterioration stage, can last for years or decades. Prominent features include reduced mobility, curvature of the spine and muscle weakness with increased muscle tone with an abnormal posturing of an arm, leg or top part of the body.