By Dr Ananya Mandal, MD
New research will soon enable couples with infertility and miscarriage and those carrying genetic disease and abnormalities to access advanced embryo screening.
Termed “preimplantation genetic screening (PGS)” the process involves a full chromosome count of embryos to ensure only the healthiest are implanted. It has a 99 per cent accuracy rate, giving hopeful parents the best chance to conceive and carry a healthy baby to term.
Monash IVF geneticist and PGS coordinator Dr Elissa Osborne said ideal candidates for screening would be older women, couples who have suffered multiple miscarriages, couples who have experienced repeat IVF failure, and known carriers of specific gene disorders, such as cystic fibrosis.
Embryos can be screened for a range of genetic conditions, including Down Syndrome, Huntington's disease and spinal muscular atrophy, before pregnancy. Dr Osborne said SNP (single nucleotide polymorphism) array testing could analyse more than 300,000 different DNA sites, much more than conventional screening.
The testing was performed on cells taken from five-day-old IVF embryos in conjunction with screening blood samples from the parents. The process is capable of screening all 23 pairs of chromosomes, with an accuracy rate of more than 99 per cent, more precise than conventional testing.
“The breakthrough with the latest SNP array testing is that in addition to screening all 23 chromosome pairs, it detects a far wider range of chromosome abnormalities and can determine the genetic source of any additional or missing chromosomes,” Dr Osborne said. “It can also detect whether these abnormalities occurred before or after fertilisation.”
Dr Osborne said old testing methods could not determine whether the chromosome abnormality came from the egg or the sperm. Now, couples could make informed decisions about potentially using donor eggs or donor sperm.
“We're very excited to be the only provider in Australia offering this test and there's a lot of interest among the scientific community as well as couples looking at IVF,” Dr Osborne said.