Scientific Advances in Chromosomal Aneuploidy Detecting

Better prenatal diagnosis of chromosomal aneuploidy

If you’re a UBC student and have taken BIOL 121, you might be familiar with the topic of genetics (the study of genes). You know what a karyotype is (a laboratory-produced image that shows the complete set of chromosomes) and you may also be aware of the devastating impact one slight change in these chromosomes can entail. 

Amniocentesis Background

Since 1930, scientists wanted to answer how severe is the Rhesus disease (antibodies of pregnant women destroy the fetus’ blood cells) and if there is a more efficient way of finding it (Link to Rhesus Disease). Amniocentesis is a prenatal test that takes amniotic fluid from around the baby in the uterus using a needle-like syringe to draw substances. This test was created to find out semi-quickly the full karyotype of the fetus to check for any aneuploidy, a side discovery that is arguably more impactful. This became a revolution as it gave incoming parents a sense of security and a better understanding of what they would need to prepare for their future child– whether the karyotype shows any abnormalities or not. 

The problem with this traditional method, however, is it carries risks. Miscarriages and infections are only a few of the negative possibilities (less than 1 percent still). This prompted research for a better, less invasive scientific method.

New Discovery

2008 marks an exceptional year towards such discovery. A noninvasive prenatal diagnosis by sequencing the genome through PCR from the mother’s plasma was found to be effective in solving the problems seen in amniocentesis. This research finds that fetal DNA in the maternal plasma–although in small doses– could be sequenced and cross-compared with a model karyotype, allowing for the detection of any aneuploidies. What have they found? When samples of 28 mothers’ plasmas from the first and second trimesters were tested, all 14 trisomies and 14 euploids were spotted correctly. This sounds incredibly powerful, but what are some improvements that can be made? The biggest has to do with its financial cost to sequence. The paper states the cost is around $700 per sample, which is around $1000/per sample nowadays. This high cost is not feasible for countries to implement at a large scale, but perhaps a more cost-effective solution will be made soon! 

By Cynthia Yan (She/They) Blog Committee

Paper source: https://www.pnas.org/doi/pdf/10.1073/pnas.0810641105