Causes of Down Syndrome

Down Syndrome is a condition where extra genetic material causes delays in the development of a child, often leading to mental retardation. The baby so born, has a flat facial profile, upward slanting eyes, small ears, an enlarged tongue and a single crease at the center of the palm. Their muscle tone is low and the joints are loose. Their entire process of growth and development is rather slow compared to other ‘normal’ babies.

‘Down Syndrome’ got its name in 1887 when a British doctor called John Langdon Down first described the condition. However, the actual cause of the disease was identified in 1959 after much research on the subject.

A baby inherits genetic information from its parents, via chromosomes. When conception occurs, a baby gets two sets of 23 chromosomes – one set of 23 from the father and the other set of 23 from the mother. This makes the total as 46 chromosomes. However, babies having Down Syndrome get an additional chromosome, making their total as 47 chromosomes.

This process is described as ‘translocation trisomy 21’. In this process, a piece of chromosome 21 gets attached to another chromosome (most often chromosome 14) during the stage of cell division. This means that chromosome 21 is also otherwise present. This increases the total number of chromosomes in the baby.

Often, one of the parents might be a carrier of the disease. This happens when the piece of chromosome 21 remains attached to chromosome 14, but duplication does not occur.

Research has shown that in 88% of the cases of babies born with Down Syndrome, the carrier was the mother. In 8% of the cases, the carrier was the father. And in the remaining 2% the cause was an error in cell division.

Maternal age has also been quoted as one of the causes of Down Syndrome. On a normal basis, Down Syndrome affects 1 in 800 babies that are born. The chances of women below the age of 30 to have babies with Down syndrome are 1 in 1000. But that figure jumps to 1 in 400 for women between the ages of 30 to 35. And for women between the ages of 35 to 42, the number jumps to 1 in 60 and it becomes 1 in 12 for women between the ages of 42 to 49.

However, modern research is still unable to find out why this anomaly occurs during the process of cell division. There is also no method of preventing this process.

But, there are ways and means through which Down Syndrome can be detected when the baby is still in the womb. There are a variety of pre-natal screening and diagnostic tests available which can determine if the baby in the womb has Down Syndrome. The accuracy of these tests is up to 99%.