Blood tests to eliminate Down146;s miscarriage risk?

According to lead researcher Dennis Lo of the Chinese University in Hong Kong, this would reduce and even eliminate the need for invasive tests that can cause miscarriage. 8220;This problem really appears to be solvable.8221; In fact, Lo8217;s method is now being commercialised by Sequenom of San Diego in California.

The approach focuses on a stretch of chromosome 21 that is only expressed in foetuses. Sequenom detects this RNA and determines which parent it comes from by identifying the differences between individuals in single letter variations 8212; single nucleotide polymorphisms, the 8216;New Scientist8217; reported.

If the amount of chromosome 21 from each parent is about the same, the foetus is healthy, but if one is about double the other, the foetus probably has Down8217;s, according to the researchers.

In another research, Stephen Quake and colleagues at Stanford University in California have developed a Down8217;s test that doesn8217;t depend on single nucleotide polymorphisms SNPs.

The team uses 8220;shotgun sequencing8221; to sequence short DNA fragments in the mother8217;s blood. Subsequently, they map each fragment to specific chromosomes and calculate proportion from chromosome 21.

In their study, they analysed blood samples from 18 pregnant women, half of which had foetuses with Down8217;s. They found that these mothers had 11 per cent more chromosome 8212; 21 fragments in their blood than the mum8217;s with healthy foetuses.

The findings have been published in the 8216;Proceedings of the National Academy of Sciences8217; journal.