Normal Fetus with two Chromosome 21’s

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Triallelic Trisomy,
fetus with Down Syndrome

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Diallelic Trisomy,
fetus with Down Syndrome

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During the normal procedure for amniocentesis, fluid is taken from the amniotic sac surrounding the fetus, under ultrasound guidance. As part of the normal growth process, fetal cells are released into the amniotic fluid. A small amount of this amniotic fluid is sent to the specialist laboratory where Amnio-PCR is undertaken.

DNA (material inside a cell that carries genetic information) is extracted from the fetal cells found within the amniotic fluid specimen. Selected areas of this DNA are labelled with a fluorescent tag and amplified by PCR. These fragments are then run on a DNA sequencer to check if there is an abnormality and finally analysed by skilled scientists with the aid of a computer programme.

In addition to Down syndrome, this highly accurate system can also detect Edwards syndrome, Patau syndrome and other chromosomal abnormalities. Single gene defects, such as common forms of cystic fibrosis, can also be detected if required.