Does poor egg quality cause Down syndrome?

Once more, we have to define egg quality because if the egg has an abnormal morphology, such as being dark or irregular, but the genetics are normal, it is unlikely to contribute to causing Down syndrome. Down syndrome is a genetic condition characterized by an extra chromosome 21. This condition is mostly due to anomalies in the chromosomes, which also have this problem, and it is often age-related.

Having poor equality that comes with the older age can increase the risk of Down Syndrome and hence why many women that are pregnant over the age of 35 they are offered prenatal diagnosis during their pregnancies. The reason is that as eggs get older they become more unstable when the egg fertilizes. We can have issues with the number of chromosomes moving across the cell division and therefore without making it too complicated in explanation it is possible that the risk of Down Syndrome and other problems of abnormalities goes up. Therefore we see that happen more often in women above the age of 35 and certainly a lot more in women that are above the age of 40.

No. Down syndrome is caused by a chromosomal abnormality which is when there are too many copies of chromosome number 21. Normally in eggs we have one copy of each chromosome and sperm have one copy of each chromosome and when they get together, we have two copies of each chromosome – one from mum and one from dad. With down syndrome, there are three copies of chromosome number 21 and that can happen because one of the eggs had or the egg that was fertilized happened to have two copies or that the sperm happened to have two copies. It’s a mix-up basically.

This is a deep question. It is generally believed that poor oocyte quality could lead to embryo aneuploidy and infants with syndromes, such as Down syndrome. However, there are different levels of accuracy when contemplating this comment. In fact, aneuploidy constitutes one of the most significant abnormalities observed in poor quality oocytes. We can say that aneuploidy is one piece of the puzzle. In order to make it crystal clear, it is widely accepted that as maternal age increases oocyte quality is progressively compromised. This reduction regarding both oocyte quality and ovarian reserve starts approximately after 30 years of age, becomes more intense after 35 and peaks after 40. It is a natural process where the cellular and the molecular mechanisms regulating proper oocyte functionality are compromised on several levels. Thus, errors are observed mainly with regards to the mechanisms regulating chromosome segregation during the meiotic divisions. Meiosis is a special category of cell division, which takes place during gamete production in both females and males. Errors in meiosis affect the number of chromosomes of gametes and in subsequently resulting embryos, finally leading to embryo aneuploidy. Thus, women of advanced age have an increased risk of embryo aneuploidy such as Trisomy 21, which is widely known as Down syndrome.