Down Syndrome was first described in detail by an English doctor, John Langdon Down, in 1866. It is a congenital condition which randomly affects about 1 in 800 babies born throughout the world, male and female alike.
A "syndrome" means a group of recognizable characteristics occurring together. A congenital syndrome is one present at birth, one which cannot be "caught" later on.
People with DS do have features in common, but they also closely resemble their parents and family. There are many characteristics attributed to DS, but any one person will have only some of them - each person is an individual, with a unique appearance, personality and set of abilities. The extent to which your child shows the physical characteristics of the syndrome is no indication of his or her intellectual capacity.
DS is one of the most prevalent chromosomal disorders and also the most easily recognized at birth because of the low muscle tone, the crease across the palm of the hand, and the sandal gap between the toes, a face that appears rather flat and the shape of the eyes. One or all these signs may be present but diagnosis can only be confirmed by the chromosomal analysis.
DS is a genetic accident which occurred at conception when one extra chromosome was included in the first cell of the baby. There are three types of DS - most common type is Trisomy 21 (95%) due to non-disjunction which occurs when two small chromosome (21) fail to separate in either the sperm or ova before fertilization occurs. The foetus formed has three chromosome 21s (instead of two) in every cell.
A rarer type is called Translocation (4%) because part of the chromosome 21 and part of another chromosome have joined to form the extra chromosome. The third type is Mosaicism (1%) which occurs during cell division after fertilization so only a portion of the baby's cell have 47 chromosomes and the rest contain 46.
It can be helpful to remember that your baby has 46 chromosomes that would have been present anyway, and only one extra (a small one) - so he or she will share the physical and personal characteristics of his parents and siblings, as well as some features of DS, making him a unique person.
The reason why this extra chromosome occurs is not known. However, it can
be said with certainty, that nothing which either parent did or did not do
caused your child to be born with Down Syndrome.
The above article is taken with permission from the book "I Have A Child with Down Syndrome - What Next?" published by Persatuan Sindrom Down Malaysia.
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