A fertilised zygote with the two polar bodies at the top (Image: BSIP/UIG/Getty

IVF success rates could go up, now that a method of detecting genetic defects in embryos has been improved.

Couples at risk of having a child with genetic abnormalities can reduce this by undergoing IVF and having their embryo genetically sequenced before it is implanted. This usually involves removing a cell from the dividing embryo, which can jeopardise the chances of it implanting.

Now Sunney Xie from Harvard University and his colleagues have developed a way to sequence the maternally inherited genome of the embryo without taking a biopsy. They do this using a technique called MALBAC (Multiple Annealing and Looping Based amplification Cycles) to sequence the polar bodies – the two cells expelled from the developing egg as it divides.

“With past methods we had too many holes in our sequencing and couldn’t get a precise enough read-out to detect both big chromosomal abnormalities and tiny sequence changes [in the polar bodies],” Xie says.


The new approach doesn’t capture any genetic defects passed down by the father but more than 70 per cent of chromosome abnormalities, the most common cause of miscarriage in older woman undergoing IVF, occur in the egg.

Team member Fuchou Tang of Peking University in Beijing says the method could improve the IVF success rate for live birth from around 30 to 60 per cent.

The team has begun a trial of polar body whole genome sequencing with 30 women with genetic disorders. “We hope to have healthy MALBAC babies in 2014,” says Xie.

Journal reference: Cell, DOI: 10.1016/j.cell.2013.11.040