Rett Syndrome is one of the five
pervasive developmental disorders
that involves severe receptive and expressive language deficits, and loss of social interactions. Onset is as early as 5 months of age, but prior to 4 years of age. It distinguishes itself from
childhood disintegrative disorder
and
asperger's disorder
with a difference in time of onset, pattern of deficits, and characteristic sex ratio(1).
Rett syndrome was originally discovered by Dr. Andreas Rett in 1954, and after researching for over 10 years, he published his findings in 1966(2). Nearly all causes of Rett syndrome are due to a mutation in the methyl CpG binding proteine 2, or MECP2 gene, which is needed for appropriate brain development(3). It appears to be a random mutation of the gene that occurs after an apparently normal prenatal and perinatal development.
The four stages, as described by the National Institute of Neurological Disorders and Stroke, are(3):
Stage I (early onset): Begins between 6 and 18 months of age. The infant may initially show less eye contact and less interest in toys. Delays in gross motor skills may be evident by the lack of sitting or crawling.
Hand-wringing and decelerated head growth may also occur, but in such a small amount that it is not very noticeable. This stage can last anywhere from a few months to more than a year.
Stage II (rapid destructive stage): Begins between ages 1 and 4 lasting for weeks or months. Language and hand skills rapidly or gradually disappear. Hand movements similar to hand washing, clapping, or tapping, as well as frequently moving hands to the mouth occur during this stage. There may be noticeable breathing difficulties including apnea and hyperventilation.
Symptoms similar to those of
autism
may appear, such as loss of social interaction and communication. Decelerated head growth and an unsteady gait is typically evident during this stage.
Stage III (plateau or pseudo-stationary stage): Begins between ages 2 and 10 lasting for years. Symptoms for this stage of Rett syndrome include, apraxia, motor problems and seizures.
There may also be an improvement at this point in previous behavior with decreased irritability, crying and other features similar to those of autism. Alertness, attention span and communication skills may show marked improvement with many girls remaining in this stage the majority of their lives.
Stage IV (late motor deterioration stage): This stage can last for years and even decades with prominently reduced mobility, scoliosis, ridgity, muscle weakness, spasticity, and increased muscle tone with abnormal posturing of an arm, leg, or top part of the body. Repetitive hand movements may decrease with an improvement in eye contact as well, but girls previously able to walk may stop walking.
DSM-IV Diagnostic Criteria
The DSM-IV Revised Fourth Edition, written by the American Psychiatric Association, uses the following diagnostic criteria(1):
Rett’s Disorder 299.80
A. All of the following:
(1) Apparently normal prenatal and perinatal development
(2) Apparently normal psychomotor development through the first 5months after birth
(3) Normal head circumference at birth
B. Onset of all of the following after the period of normal development
(1)
Deceleration of head growth between ages 5and 48 months
(2) Loss of previously acquired purposeful hand skills between ages 5 and30 months with the subsequent development of stereotyped hand movements (e.g., handwringing or hand washing)
(3) Loss of social engagement early in the course (although often social interaction develops later)
(4) Appearance of poorly coordinated gait or trunk movements
(5) Severely impaired expressive and receptive language development with severe psychomotor retardation.
References
1. American Psychiatric Association. (2000). Pervasive developmental disorders. In Diagnostic and statistical manual of mental disorders (Fourth edition---text revision (DSM-IV-TR). Washington, DC: American Psychiatric Association,76-77.
2. International Rett Syndrome Foundation. About Rett Syndrome.
.www.rettsyndrome.org.
11-25-09.
3. National Institute of Neurological Disorders and Stroke.
Rett Syndrome Fact Sheet.
www.ninds.nih.gov. 11-25-09.
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