Israeli scientists are holding trials on a new method of screening for fetuses and say it could provide all the information received from an amniocentesis without the risks.
Prof. Noam Shomron of Tel Aviv University told The Times of Israel that his method involves taking a regular blood sample rather than the amniocentesis practice of using a needle to extract amniotic fluid, which carries a risk of miscarriage.
He said the new technique can be performed four weeks earlier than amniocentesis — at 10 weeks instead of the standard 14 — and provides as much information on the risks of numerous syndromes, diseases and disorders.
“We can screen for thousands of mutations, each of which could lead to genetic diseases,” he said, naming Gaucher’s and cystic fibrosis as two diseases.
It also works for less common mutations such as those that occur more among particular demographics, like Tay Sachs which is more prevalent among Ashkenazi Jews.
Shomron, who heads Tel Aviv University’s functional genomics lab, published the method in peer-reviewed research and is developing the technology via a startup, IdentifAI Genetics, which he leads with colleagues Tom Rabinowitz and Oren Tadmor. The new screening process is being tested on dozens of Israeli women — who tend to corroborate any results with amniocentesis — and Shomron said he expects it to be approved by regulators and available for use by the end of 2023.
After the method is eventually perfected for embryos, it could be adapted for screening children and adults for a range of diseases that manifest themselves with abnormal DNA, such as cancers, Shomron said.
His method isn’t the first alternative to amniocentesis. A blood test called the noninvasive prenatal test, or NIPT, is in wide use and provides reliable screening for various conditions including Down’s syndrome, Edwards’ Syndrome and Patau’s syndrome. However, its scope is limited and it can only screen for large chromosomal changes, not hard-to-detect mutations.
NIPT only identifies genetic changes that can be spotted by examining the chromosomes, while many mutations require the analyst to zoom in. Shomron captures detail within the chromosomes.
“Our resolution is about a million times better than that of NIPT,” said Shomron, likening it to high-detailed satellite imaging that can now show individual buildings, compared to early space flight images that could only show the outline of land masses. “We look at each nucleotide, each base, each letter in the genetic material, the DNA.”
One key breakthrough that led to Shomron’s method was identifying which DNA in the mother’s blood belongs to the fetus. This is challenging because the mom’s blood contains her DNA as well as that of the fetus; NIPT hasn’t overcome this, meaning analysis takes place on a mixture of DNA, some of it irrelevant to the fetus.
Shomron and his team built an algorithm that differentiates between the DNAs based on subtle variations in size, shape and other characteristics.
“This means we get the computationally purified DNA and can then go back to looking at every tiny change in the DNA, and this just isn’t possible when it is mixed in with the mother’s DNA,” he explained.
“When you read the mother and fetus’ DNA together, things are unclear and you only see major changes to the norm, while when you know exactly what belongs to the fetus you get a very clear view. The result is that the new test will give everything a current amniocentesis or NIPT delivers, together with significant additional information.”