Wednesday, August 02, 2006

Clinic Notes: Down Syndrome and Autism

Last year I had a child come to my clinic with Down Syndrome who had recently developed autism. Recent studies find that 7 to 10 percent of children with Down Syndrome also have autism. I think that it is more appropriate to say that they exhibit some autistic behavior. In 1959 the genetic basis of Down Syndrome was found to be trisomy 21 in 95 percent of the cases and the extra chromosome is usually maternal in origin. People with Down Syndrome are depicted in ancient art; so apparently the disorder has been around for a long time. In 1866 Dr. John Langdon Down wrote about the facial similarities of many of his patients with mental retardation using a racial description (Mongol), which unfortunately stayed around for nearly a century. Once the genetic basis of the disorder was known ,the terminology changed and now the correct terminology is to refer to them as persons with trisomy 21 or a person with Down Syndrome. See for a detailed discussion of Down Syndrome.
Women older than forty or mothers who already have a child with Down Syndrome are more likely to give birth to babies with Down Syndrome, and routinely undergo amniocentesis at sixteen weeks. Taking into account surgical and spontaneous abortions the incidence of Down’s is approximately one in every eight hundred births. Younger mothers who do not undergo amniocentesis deliver the majority of Down’s babies because they don’t get tested. A new test, which combines blood tests and an ultrasound, is 90 percent accurate in the first trimester and can be done four to six weeks earlier than the standard Triple Test. (We understand more about genetics now than we did in John Donne’s day. But it seems like fate still plays a role.)
Children with Down’s have a variety of physical characteristics. Most of these children do not reach adult height. The head is usually smaller (microcephaly) and the nose may be flattened. The tongue protrudes and the eyes slant upward. Many children with Down’s have a rounded fold of skin (epicanthal fold) in the inner corner of the eye. The hands and fingers are broad and have a single crease in the palm. Medical problems may include congenital heart defects, gastrointestinal problems, hypotonia, and acute lymphocytic leukemia. The average mental age is eight years.
Some newborns with Down Syndrome have visual and hearing deficits. Cataracts occur in 3 percent of the cases and glaucoma is more likely also. Hearing should be tested on a yearly basis according to some experts. Hypotonia not only affects mobility it also affects feeding. The protruding tongue means feeding will take longer and dysphagia (difficulty in swallowing) and choking episodes are common. The usual developmental milestones are globally delayed.
Ten percent of kids with Down Syndrome have seizure disorders which are usually tonic clonic. In older patients with Down Syndrome, seizures associated with Alzheimer’s often develop.
Children with Down Syndrome usually do well with ABA. When autistic behavior develops with Down Syndrome the ABA is more difficult.
Go to and read case number 15 for additional information on Down Syndrome.

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