快猫短视频

WITHIN a few years it could be possible to boost the success of IVF by
checking for major chromosomal abnormalities before embryos are transferred to
the womb.

鈥淧otentially, this is a major advance,鈥� says Mark Johnson of Imperial
College, London. At present, it is only possible to check a handful of
chromosomes. But by adapting existing techniques, Joy Delhanty and Dagan Wells
of University College London were able to check all the chromosomes in 12
three-day-old embryos.

Abnormalities were surprisingly common, Delhanty says. Only three of the 12
embryos had the right number of chromosomes in all their cells.

The researchers used a technique called comparative genomic hybridisation
(CGH). They compared the chromosomes from the embryos with ones from normal
cells by staining them with different dyes. Any departures from the normal
number of chromosomes, or any large deletions or insertions, show up as
differences in the amount of fluorescence.

Large amounts of DNA are needed for CGH, so Delhanty and Wells had to make
many copies of a cell鈥檚 DNA by improving on a second method known as whole
genome amplification.

At present the test takes three or four days鈥攆ar too long for
pre-implantation screening, says Delhanty. The time will have to be reduced to
around 24 hours to make it practical, she says. 鈥淚t鈥檒l be a year or two before
it might be applied.鈥�

They looked at every cell in the embryos in their study, but when the test is
used for screening, technicians will only be able to test one or two. 鈥淵ou can
never be sure that the rest of the embryo is normal,鈥� Delhanty says.