Down syndrome was first
identified over a century ago, and the last thirty years have
brought remarkable progress in understanding the chromosomal basis
and risk factors for this condition. Physicians are currently able
to identify the risk of having a child with Down syndrome from
non-invasive procedures such as ultrasound and biochemical maternal
blood screening. High risk patients are then routinely offered an
invasive diagnostic procedure.
Conventional karyotyping of cultured amniocytes and CVS mesenchyme has been performed as a reliable, cost-effective and accurate means of prenatal genetic diagnosis for a wide range of chromosome abnormalities. However, the disadvantage of these methods is the delay of up to three weeks during which the cells must be cultured prior to analysis.
The total waiting time of up to four weeks often poses difficult clinical and psychological problems.
Amnio-PCR can reduce this waiting time significantly by the polymerase chain reaction technique. PCR amplifies and enables quantification of specific regions of the DNA molecule from uncultured amniocytes and CVS tissue to provide a definitive result within 24-48 hours.