Blodprov avslöjar genetiska
abnormiteter i fosterstadium

A simple blood test taken by a pregnant woman could reveal genetic abnormalities such as Down’s syndrome in her developing fetus, scientists say, removing the need for some invasive tests.

The researchers have developed a new way of extracting and analysing the fetal DNA that circulates in maternal blood, which could lead to accurate tests for genetic disorders, just five weeks into the pregnancy.

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The new approach relies on the fact that the placenta sheds fetal cells into a woman’s blood stream from five weeks into pregnancy. The mother’s immune system breaks these cells down once they enter her bloodstream, releasing the fetal DNA.

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With a decent proportion of fetal DNA harvested, researchers look for genetic markers called single nucleotide polymorphisms (SNPs). They compare these with the SNPs found in the maternal and paternal DNA.

Because we inherit a copy of each gene from both of our parents, the fetal DNA should contain an equal number of SNPs, matching those belonging to the mother and father.

In certain cases, however, the test might find that there are twice as many SNPs in the fetal sample that match the paternal code than match the maternal code. This disproportion would indicate that the child has an extra copy of a chromosome from the father, Dhallan explains. ¹

Tack vare den vetenskapliga utvecklingen så kan vi nu göra en uppskattning över fostrets hälsa i framtiden, baserat på den genetiska strukturen som kopierats från far och mor.