New chromosome counting technique

The first babies have now been born in the UK using a new technique pioneered at Oxford University to select the best embryos for IVF. The advance could bring hope to many British couples struggling to have a child and going through many cycles of IVF treatment. The technique used called microarray CGH with IVF allows the embryos to be checked for the right number of chromosomes before implantation in an IVF treatment, lessening the chance of miscarriage or Down’s syndrome.

The strategy of applying microarray CGH, or comparative genomic hybridisation, to five-day-old embryos, or ‘blastocysts’, was developed by Dr Dagan Wells and Dr Elpida Fragouli at the University of Oxford, with funding from the Oxford Biomedical Research Centre and in collaboration with partners in the health services and industry.

“If a sperm and egg come together and produce an embryo with the wrong number of chromosomes, the embryo will usually fail to establish a pregnancy or miscarry” explained Dr Dagan Wells of the Nuffield Department of Obstetrics and Gynaecology.

As with routine IVF treatment, several eggs are produced and fertilised. Five days later at the blastocyst stage, a small number of cells are removed from the growing embryo and microarray CGH is used to check for any significant abnormalities present in the chromosomes. In effect it scans the DNA packed up in the cells’ chromosomes for any clear problems. Results are available 24 hours later. Based on this information, it is possible to make sure that only embryos with the correct number of chromosomes are transferred in IVF, improving pregnancy rates as a result.