Down Syndrome Screening

What is Down syndrome?
Down syndrome is one if the most common chromosomal condition that a baby can be born with. it is the most common cause of significant mental retardation and learning disability in children. It can happen to anyone regardless of age but much more higher risk in older women.

Down syndrome is also known as Trisomy 21.

What causes Down syndrome?
Normally, every cell in the human body — except egg and sperm cells — has 46 chromosomes. The egg and sperm cells normally have 23 chromosomes each.

The most common cause of Down syndrome is when an extra copy of chromosome 21 randomly appears in either the egg or sperm. At conception, when the egg and sperm meet, the extra copy of chromosome 21 grows throughout all of the embryo’s cells, giving them each 47 chromosomes instead of the usual 46.

Less commonly, the extra copy of the chromosome can appear in some of the embryo’s cells after conception. This is called mosaicism and results in some cells having 46 chromosomes and some having 47.

Another rare form of the syndrome is caused by ‘Robertsonian translocation’. This occurs when a piece of chromosome 21 breaks off and becomes joined to another chromosome before or after conception. In this case, the embryo’s cells will all have 46 chromosomes, but each cell still contains an extra copy of chromosome 21.

What are the most common features of Down syndrome?
Many babies with Down syndrome have one or more of the following features at birth:

• low muscle tone ('floppy' muscles)
• a flatter face with eyes slanting upward
• small ears and a wider neck than usual
• a single crease across the palm of the hand
• a gap between the first and second toes