Some IVF Drugs May Increase Risk of Down’s Syndrome
UK researchers have raised concerns that drugs used in IVF for older women may increase the child of having a child with Down’s Syndrome, as well as IVF failure and pregnancy loss. It’s already known that older women are at increased risk for having a child with the developmental disorder, which occurs when a fetus carries an extra copy of chromosome 21. But after studying 34 couples (with the women all over the age of 35) undergoing fertility treatment in the form of receiving drugs that “kick-start ovaries for IVF,” the researchers have raised concerns that the drugs themselves may be “disturbing the genetic material” of the eggs, says the BBC.
The fertility drugs the women were given stimulated their ovaries to release more oocytes (egg cells) than usually, to provide a sufficient amount of “good quality oocytes” for fertilization in vitro. Scientists used a new technique, microarray comparative genomic hybridization (array CGH) that enabled them to screen polar bodies, which are small cells that are the by-product of oocyte development; this new method helped scientists to more fully analyze the oocytes at the chromosomal level.
It was in looking at that data that scientists were able to see that some of the now-fertilized eggs had genetic errors. Says Professor Alan Handyside, Director of The London Bridge Fertility, Gynaecology and Genetics Centre, London, UK, in Science Daily:
“What happens in female meiosis is that the 23 pairs of chromosomes duplicate and each pair of duplicated chromosomes comes together and the four single chromosomes, or ‘chromatids’, become ‘glued’ together along the whole length of each chromosome. This actually occurs before the woman is born and is the stage at which DNA is swapped between the grandparents’ chromosomes.
“Sometimes, decades later, just before ovulation, the glue ‘dissolves’ first between the two duplicated chromosomes and finally after fertilisation between the two individual chromosomes. This enables pairs of chromosomes to segregate in the first meiotic division producing the first polar body. In the second meiotic division the second polar body is produced, resulting in a single set of chromosomes in the fertilised oocyte or ‘zygote’, which, when combined with the single set in the fertilising sperm, restores the 23 pairs,” he says.
The researchers believe that ovarian stimulation may be disturbing this process in older women because the chromosomes are becoming unglued prematurely, particularly the smaller ones like chromosome 21.
While scientists had previously thought such chromosomal abnormalities were due to the age of the egg, the concern is that the drugs themselves are affecting the eggs, by somehow affecting the process of meiotic divisions. The scientists are continuing testing. If more results back up their findings, this will suggest that “doctors should be more cautious about using these treatments” and also whether, in some cases, women might be “better off using donor eggs,” rather than using the drugs causing ovarian stimulation.
The researchers’ findings were presented at the annual conference of the European Society of Human Reproduction and Embryology and have yet to be published.
Should the researchers’ preliminary findings about a link between some IVF treatments and an increased risk of having a child with Down’s Syndrome be further substantiated, parents who undergo IVF treatments need to receive not only basic information about the disorder and also about — though some might find this curious — the positive aspects of having a child with Down’s. About 85 percent of Down’s pregnancies are terminated and parents of children with Down’s have been concerned that, with fewer individuals with Down’s, their children may face a world not only less knowledgeable but less attuned to their needs and, yes, strengths. I can tell you first-hand that it is very challenging raising a child with developmental delays, but not at all impossible. It’s an experience we are more than grateful for every day we spend with our beloved boy. But women need to be fully informed about what can happen when they use IVF treatments and, it is hoped, the work of Handyside and his colleagues will make these as risk-free to mother and child as possible.
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