Complete cytogenetic investigation of oocytes from a young cancer patient with the use of comparative genomic hybridisation reveals meiotic errors
Fragouli E, Wells D, Doshi A, Gotts S, Harper JC, Delhanty JD
Prenat Diagn. 2006 Jan;26(1):71-6
In order for the embryo to have the correct number of chromosomes when the sperm fertilizes the egg during reproduction, the chromosomes in both the egg- and sperm-producing cells must undergo a series of divisions called meiosis. A range of chromosome abnormalities can occur in human eggs that can result in miscarriage or birth defects. Failure of the chromosomes to divide correctly during meiosis ranks amongst the most common of these abnormalities. Such division errors are generally thought to occur more commonly in the eggs of older women.
A range of techniques are available for the analysis of human eggs for chromosome division errors. However, these methods do not all have good reliability and cannot be used to analyse the full compliment of chromosomes simultaneously. The current study evaluated the efficacy of a new technique – comparative genomic hybridization (CGH) – for investigating the full compliment of chromosomes in human eggs. The researchers used CGH to evaluate the chromosomes in 14 eggs that had been collected from an 18-year-old woman before she underwent treatment for leukaemia. Sadly she had died and her eggs were donated to medical science.
The chromosome compliment was successfully investigated in 11 of the 14 eggs; three different chromosome division errors were identified in two of these eggs. The study showed that CGH can be used successfully to analyse the full compliment of chromosomes in human eggs in terms of both extra and missing genetic material.
These data are of great interest for two reasons. Firstly, it is unusual for researchers to be able to analyse a large collection of eggs from the same woman. Secondly, the patient was young and had no known fertility problems. It was previously thought that division errors occur primarily in the eggs of older women. However, the present study showed significant division errors in two out of 14 eggs from a young patient. These results confirm that age-independent division errors can occur that contribute to abnormalities in human eggs. These findings are particularly relevant to fertility treatments. Currently, the screening of eggs for abnormalities before in vitro fertilization (IVF) treatment is only recommended for women aged over 37 years of age. The authors suggest that screening may also be advisable in certain subgroups of younger women before eggs are implanted during IVF procedures.
There are many ways you can donate to Wellbeing of Women. Your donation will help us continue to fund research into all aspects of reproductive health.
Need to contact Wellbeing of Women?
wellbeingofwomen@rcog.org.uk
Tel: 020 7772 6400
Fax: 020 7724 7725