Of older moms and Down’s Syndrome

India’s urban elite has plenty of DINKs (Double Income, No Kids). These people get married later than their rural counterparts, often after they are financially and professionally independent and secure. They can afford the best, as far as pregnancy, antenatal care and delivery are concerned. Eventually, they limit their families to one or maybe two children for whom they wish to provide the best opportunities in life.

Under these circumstances, the birth of a child with Down’s Syndrome (trisomy 21 or mongolism) becomes an unbearable tragedy.

One in 800 children is born with Down’s Syndrome. Such children have a characteristic “mongoloid” appearance at birth itself, irrespective of the parents’ ethnic backgrounds. The head may be smaller than normal with a sloping forehead, upward slanting eyes, a small flattened nose, low set ears, short stumpy fingers, a protuberant abdomen and a tongue which sticks out of a small mouth. Also, the palm shows just two lines instead of the usual three.

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Down’s Syndrome usually occurs spontaneously as a result of an anomaly during early embryonic cell proliferation producing an abnormal chromosome 21. During cell division it may have divided abnormally, producing three parts instead of the normal two. Sometimes a piece from the chromosome may have attached (translocated) itself to another chromosome.

These anomalies are more likely with increased maternal age at the time of the pregnancy. Many doctors and researchers consider the age 35 as the cut off.

The child shows all the typical features of Down’s Syndrome if all the cells contain the abnormal chromosomes. Sometimes the person may be a mosaic, with a mixture of normal and abnormal cells. The appearance may then be atypical.

The risk of recurrence is greater if the condition has arisen as a result of translocation. This is because one of the parents is then likely to be a carrier. The risk is around 3 per cent if the father is the carrier, and 12 per cent if the mother carries the abnormal gene. Also, a mother with a Down’s Syndrome child has a one per cent chance of producing another similarly affected child.

Life is difficult for children suffering from Down’s Syndrome as they often have subnormal intelligence. They may also have abnormalities in other organs like the heart. There may be blocks or malfunction of the gastrointestinal tract with constipation and intestinal bloating. Hearing loss or visual defects may also occur. The chromosomal abnormality causes a decreased immune response, causing frequent infections as the children grow. The incidence of leukaemia is 20 times greater than in the general population. Dementia too sets in during early adult life (around 40). All this means a lifetime of nurturing and extra care.

So does this mean that women should sacrifice education and professional careers for early marriage and childbirth?

Not really, as advances in medical science have made it possible to diagnose Down’s Syndrome during the antenatal period itself.

Ultrasound examination during the first trimester has a detection rate of approximately 95 per cent of all Down’s Syndrome cases. The measurement of nuchal translucency — the size of a collection of fluid at the base of the foetal neck — correlates with the risk of Down’s Syndrome. Other markers like the size of the head, the nose, the presence or absence of heart and intestinal defects can be evaluated with a scan. The presence of several abnormal markers may be an indication of Down’s Syndrome.

Moreover, certain blood tests performed on the mother can show abnormal results if the foetus is affected. Of these, the one commonly available in India is the alpha-fetoprotein level which tends to be less than normal in Down’s Syndrome.

To confirm the diagnosis, the chromosomes of the foetus can be examined. This can be done with amniocentesis (an examination of the cells in the amniotic fluid that surrounds the baby in the uterus). The diagnosis takes two weeks.

The cells of the placenta can be also tested during the 10th and 12th weeks of pregnancy by Chorionic Villus Sampling (CVS). If a rapid diagnosis is required, Percutaneous Umbilical Blood Sampling (PUBS) can be done after 18 weeks of gestation. Each of these three tests is 98 to 99 per cent accurate in diagnosing Down’s Syndrome. However, all these tests carry a risk of miscarriage.

After birth, Down’s Syndrome is suspected because of the typical appearance of the baby. It is confirmed by karyotyping or checking the baby’s chromosomes to demonstrate the extra chromosome in the cells.

Unfortunately, much of this high-tech diagnosis is out of reach for the average Indian woman. Financial constraints, poor education and lack of facilities are major drawbacks to good antenatal care and prenatal diagnosis.
Source:Thr Telegraph (Kolkata,India)

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