Autism » Spectrum Disorder » Rare Spectrum Disorders
Rett syndrome:
Rett syndrome is relatively rare, affecting almost exclusively females,
one out of 10,000 to 15,000. After a period of normal development, sometime
between 6 and 18 months, autism-like symptoms begin to appear. The little
girl's mental and social development regresses; she no longer responds
to her parents and pulls away from any social contact. If she has been
talking, she stops; she cannot control her feet; she wrings her hands.
Some of the problems associated with Rett syndrome can be treated. Physical,
occupational, and speech therapy can help with problems of coordination,
movement, and speech.
Scientists sponsored by the National Institute of Child Health and Human
Development have discovered that a mutation in the sequence of a single
gene can cause Rett syndrome. This discovery may help doctors slow or
stop the progress of the syndrome. It may also lead to methods of screening
for Rett syndrome, thus enabling doctors to start treating these children
much sooner, and improving the quality of life these children experience.
Childhood disintegrative disorder:
Very few children who have an autism spectrum disorder diagnosis meet
the criteria for childhood disintegrative disorder (CDD). An estimate
based on four surveys of ASD found fewer than two children per 100,000
with ASD could be classified as having CDD. This suggests that CDD is
a very rare form of ASD. It has a strong male preponderance.** Symptoms
may appear by age 2, but the average age of onset is between 3 and 4 years.
Until this time, the child has age-appropriate skills in communication
and social relationships. The long period of normal development before
regression helps differentiate CDD from Rett syndrome.
- Rett syndrome. NIH Publication No. 01-4960. Rockville, MD: National
Institute of Child Health and Human Development, 2001.
- Frombonne E. Prevalence of childhood disintegrative disorder. Autism,
2002; 6 (2): 149-157.
- Volkmar RM and Rutter M. Childhood disintegrative disorder: Results
of the DSM-IV autism field trial. Journal of the American Academy of Child
and Adolescent Psychiatry, 1995; 34: 1092-1095.
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