Down syndrome or Trisomy-21 or Mangolism

Down syndrome or Trisomy-21 or Mangolism

People with Down syndrome are born with an extra chromosome.

With Down syndrome, this extra chromosome leads to a range of

issues that affect you both mentally and physically.



Normally, each cell in your body has 23 pairs of chromosomes.

One chromosome in each pair comes from your mother.

The other comes from your father.

But with Down syndrome, something goes wrong and you

get an extra copy of chromosome 21.

That means you have three copies instead of two,

which leads to the signs and symptoms of Down syndrome.



Nuchal translucency scan

Nuchal translucency is a newly introduced ultrasound test

that measures the thickness of the fluid accumulated in the region of the base of the fetus's head.

The most reliable results are obtained between the 11th and the 13th week of pregnancy.

In fetuses with chromosomal abnormalities,

cardiac defects and many genetic syndromes the NT thickness is increased.

Screening by NT can detect about 80% of fetuses with trisomy 21 and other

major aneuploides for a false positive rate of 5%.



Why is nuchal translucency testing performed?

During fetal development, between the 11th and the 14th week,

fluid accumulates under the skin in the scalp and nape region. In cases

where there is excessive fluid (usually a fluid band of greater than 3 mm width)

there is an increased risk of a fetus with both chromosomal defects

and anatomical defects. This test can detect women who are at increased risk

for having infants with chromosomal or structural disorders.