Until now genetic screening of embryos for chromosomal abnormalities has required taking a few cells from the embryo. The disadvantages of this are a small risk of damage to the embryo and the cost involved in the procedure
The new test looks at the fluid that the embryo has been growing in. This contains traces of DNA from the embryo.
How non-invasive embryo testing is developing globally
US company PerkinElmer showcased their new niPGT-A testing kit at a scientific congress in Philadelphia this month. They’ve collected data from 15 laboratories worldwide comparing biopsy result with culture medium results and have found more than 90% correlation between the two. Not perfect but a very good start.
In Australia Monash IVF began offering non-invasive testing in all it’s clinics in May and they report 95% concordance between biopsy and culture medium results. The test is available for $495 (£263) per embryo.
Where is the DNA being released from?
The procedure remains controversial – genetic consultant Dr Antonio Capalbo presenting at an ESHRE meeting in September stated that more questions need answering before the test is ready for clinical use.
A concern is that we don’t yet know exactly where the DNA in the culture medium is coming from. It’s not certain that it’s coming from the inner cell mass of the embryo, or may come from cells surrounding the embryo. Contamination with other DNA could affect results.
In the UK a case study at IVF clinic CRGH combined both invasive and non-invasive testing on two embryos resulting in ongoing pregnancy. The study states non-invasive testing to be an addition to diagnosis rather than a replacement for embryo biopsy. At least until we know more.
Advantages of non-invasive embryo screening
no need to wait until the embryo has hatched, so information is more easily obtained about each embryo
it is possible that the fluid may show a more complete picture of the embryo’s genetic health than taking a few cells with biopsy – research is ongoing with this
Disadvantages of non-invasive embryo screening
can only be used on embryos which have been fertilised by ICSI - this is to avoid picking up the sperm’s DNA instead of the embryo’s DNA
embryos need to be cultured until day 6 - getting sufficient DNA into the culture medium takes time
a small percentage of embryos may not release enough DNA into the culture medium