Down syndrome is found to be the most common genetic cause of mild to moderate mental retardation and other related medical problems in newborns. One in every eight hundred newly born babies experiences this disorder. Newborn infants with the Down syndrome are likely to have one or other of the following symptoms. These include flat facial profile, an upward slant to the eye, abnormally shaped ears, a short neck, white spots on the iris of the eye, and a single, deep transverse crease on the palm of the hand.
Chromosomal irregularities result in this condition. In babies with Down syndrome, an irregularity occurs in the cell division of the fertilised egg and thereby contains certain additional elements. Such an irregularity is the most common cause of this syndrome. In roughly two to four percent of cases, irregularity occurs in the cell division during some initial stage of embryonic development. In approximately 3-4% of individuals with Down syndrome, the problem occurs either before or during the time of conception itself. In such a situation, the irregularity might get repeated in future pregnancies as well.
Mostly, the occurrence of Down syndrome is the result of a random event that happened during the formation of the reproductive cells. No scientific proofs have been obtained to attribute the occurrence of the syndrome to any environmental features or behavioural activity of the parents.
However, research in this field points out that babies affected with Down syndrome are born mostly to mothers who are above thirty-five years of age. So, it is advisable for such pregnant women to undergo pre-natal testing in order to be on the safer side.
The pre-natal screening test for Down syndrome is comparatively simple. A mere drop of the mother’s blood is enough for analysis. An increased likelihood for Down syndrome is measured by examining the levels of three markers namely, serum alpha feto-protein (MSAFP), chorionic gonadotropin (hCG), and unconjugated estriol (uE3). In case of suspicion, the mother can be subjected to other more detailed diagnostic tests as well.