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Down Syndrome

What is Down syndrome?

Down syndrome is a congenital condition in which varying degrees of mental retardation are often present. It is one of the most common birth defects, affecting about 1 in every 1,000 babies. The risk of Down syndrome is greater in older mothers.

Children with Down syndrome often grow slowly, have weak joints, and are at risk of infections, blood disorders, and low thyroid levels. They are also at risk of visual and hearing impairments. These children tend to have eyelids that slant upwards, small folds of skin at the corners of the eyes, and slightly flat noses.

What causes Down syndrome?

Down Syndrome Karyotype
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People with Down syndrome have an extra copy of chromosome 21.
Down syndrome is caused by an extra copy of chromosome 21. Chromosomes contain the genetic material that determines all our inherited characteristics. As a result, the most common form of the disease is called trisomy 21 since there are 3 copies of this chromosome instead of the usual 2 copies. It usually results in delays and limitations in physical and intellectual development.

What heart conditions may be associated with Down syndrome?

About 40% of children with Down syndrome are born with heart defects, many of which can be corrected through surgery. Children identified as having Down syndrome are routinely screened for congenital heart defects. Atrioventricular septal defects are the most common type of defect in children with Down syndrome.

If surgery is required to correct these defects, it usually takes place within 4 to 6 months of birth.

What is the long-term outlook for children with Down syndrome?

Life expectancy is thought to be about 55 years, though this can vary. The life expectancy for children with Down syndrome has doubled over the past 20 years. The mortality rate is higher than average, however, usually due to respiratory or cardiac complications.

Children with Down syndrome face many challenges, but many are able to live full lives. They will each have their own capabilities and talents that they will develop in the face of mental, behavioural, and physical development challenges. With appropriate care, medical support, and special education, these children in many cases can look forward to leading semi-independent lives.

For more information about Down syndrome, please ask to be referred to a genetic counsellor.

Fraser Golding, MD, FRCPC

12/14/2009




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