What are the methods of prenatal diagnosis? There are two groups: invasive and non-invasive techniques:

  • Non-invasive methods:
    • examination of the uterus from outside the body (see Leopold's Maneuvers)
    • ultrasound technique (like the 4D ultrasound)
    • AFP screening
    • Detection of fetal blood cells that have made their way into the mother's bloodstream, so we can obtain a sample of the baby's DNA.
  • Invasive methods:

Obviously, the aim is to develop a method which is

  • safe (some invasive tests pose a risk to the pregnancy)
  • sensitive (ultrasound detection may suffer from a high rate of false negatives and false positives)
  • cheap (you know our modern world very well)
  • non-invasive

Now, scientists are trying to create a non-invase blood test by examining samples of foetal DNA present in the mother's blood for variations in the sequence of the genetic material. These variations are known as single nucleotide polymorphisms (SNPs). According to the BBC article:

The Ravgen team, led by Ravinder Dhallan, has been able to maximise the amount of DNA that can be recovered by treating the blood samples with a chemical called formaldehyde.

Ravinder Dhallan, a doctor and researcher, founded Ravgen (Rapid analysis of variations in a genome) in 2000 with the goal of solving major clinical problems. The key to early diagnosis and improved treatment lies in separating relevant, disease-associated genetic signals from the background of non disease-associated signals.

What could be the benefits of that new method?

  • Being able to identify genetic abnormalities at an early stage not only gives parents the chance to decide whether or not to proceed with the pregnancy, but also alerts medical staff to the need for close monitoring right through to birth.
  • They were also able to determine whether the foetus was carrying extra copies of key chromosomes which cause genetic disease such as Down syndrome or Klinefelter syndrome.
  • An accurate non-invasive test would mean a lot women with normal babies would not have to be put through a procedure like amniocentesis.

Although, if I want to be neutral, I should list the other side's concerns:

  • The amount of free foetal DNA in maternal blood is low, and although the use of formaldehyde allows an increased amount to be isolated from maternal blood, yields are irregular.
  • Only eight women have been assessed in the first trimester - further testing in this stage of pregnancy will be essential.