IVF Chromosome Technology

Published on Friday, 01 April 2011 15:00

 

By Charna Walfall

 

Scientists and medics have discovered a new and amazing technique that in the future could result not only in increasing the success rate of IVF treatment but reducing the amount of cycles that patients have to go through.

 

What is IVF?

IVF stands for “in vitro fertilisation”. This is a process where egg cells are fertilised by the sperm outside of the body.

It involves hormonally controlling ovulation process. Once the egg and sperm are fertilised the zygote is transferred to the patients uterus where the pregnancy will continue. IVF is used to help couples who are finding it difficult to conceive naturally.

Why IVF would not be successful

However, not all couples that undergo IVF are successful. Any imbalances or chromosomal changes like micro duplications can cause birth defects, development delay or even mental retardation. For a cycle to be successful, an embryo needs to have 23 chromosomes.

Embryos produced in the average cycle may have sections of DNA missing, due to incorrect amounts of chromosomes or duplication of chromosomes.

The assessment used for IVF is unable to differentiate between embryos with significant chromosome problems and those that are healthy and normal.

Revolution in technology

A new test has been devised that could revolutionise IVF treatment.

This new technique involves applying ‘micro comparative genomic hybridisation’ (CGH). This high resolution test can detect even the slightest imbalance of chromosomes that could be present.

The strategy of applying microarray CGH to five-day-old embryos, or 'blastocysts', has been 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.

The technique itself involves a laser which cuts a hole in the edge of the egg. Using a pipette the polar body is removed. The polar body is where the spare chromosomes are found. These chromosomes reflect those that are left in the egg.

As these chromosomes are spare this allows the chromosomes to be tested without the egg itself being damaged or harmed. This therefore gives the doctors an indication of what is left behind in the embryo.

The way in which the technique works is by establishing whether there are extra chromosomes or if there are distinct problems that examining the egg through a microscope would not detect.

This is done by scanning the DNA in the cells to identify any prominent problems. A benefit that comes from this process is that results are available as early as 24 hours later. This prevents patients having to wait anxiously for long periods of time.

This technique therefore establishes which embryos have the correct amount of chromosomes and only these healthy embryos are then transferred into the womb. This is something that at present is not available as embryos are chosen to be implanted at random, so a successful pregnancy could be seen as ‘pot luck’.

A trial in the USA using this technique was conducted two years ago. Of those women that the technique was trialled upon, 18 had successful pregnancies and 10 were pregnant at the end of the experiment; all of whom had had their eggs screened before implantation.

The most recent research into this subject showed that “pregnancy rates after chromosome testing were increased by 50% of the 200 participants undergoing IVF”.

Other research that has been conducted suggests that CGH has a 95% accuracy rate of detecting any abnormalities that maybe present in embryos which therefore increases the chance of successful full-term pregnancies.

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Who could CGH benefit?

Microarray CGH is able to identify embryos that are most likely to have the best chance of a successful pregnancy and reduces the possibility of down syndrome or even miscarriage.

This technique would be beneficial to those couples who have undergone several cycles of IVF. As this technique stops problematic embryos being implanted, this would, in turn, reduce the amount of cycles required to conceive and potentially save the patient vast amounts of money.

The process of the technique removes any ethical issues of embryos being created and then destroyed as the initial testing is conducted on the egg itself. The process itself does not harm or affect the actual embryo, as the selection is taken from unwanted or spare cells. It is also taken before the embryo is transferred into the uterus where the pregnancy will begin.

During IVF treatment at least half of the embryos that are created are wasted because of abnormalities that are present. This means that patients often have to undergo several cycles to establish a successful pregnancy.

CGH allows the potential successful chromosomes to be selected and then implanted which eventually would establish a successful pregnancy.

This can be seen in the case of Nicole Klieff who spent £60,000 and underwent six cycles of treatment. However, on her seventh attempt she successfully gave birth to a beautiful baby girl.

Throughout her treatments Nicole experienced all kinds of emotions and she would have held on to any shadow of hope that would increase her success rate. If Nicole had been given the option of the CGH technique this could have stopped her from suffering two miscarriages.

Success story

A couple named George and Helen are believed to the UK’s first couple to have undergone this wonder technique with successful results; they welcomed the birth of twin boys.

This therefore makes them living proof that this technique is not only beneficial but also successful. The Ashtons had undergone five cycles of treatment before they had a successful pregnancy.

During this time they were told by doctors that the reason for their misfortune could be due to poor embryo selection.

Eventually the couple went to an Oxford fertility unit where they underwent the chromosome testing. George said, “this technique has been a godsend to us [...] the problem is that very few people know about it.”

A member from the hospital also adds that “they have had a number of couples who have had treatment which has resulted into a successful pregnancy.

Conclusion

Despite all the theory and successful results, the technique is still in its very early stages and a long way from completely transforming the success rate of IVF. More intense research is needed into the process to establish reliability and efficiency.

With all of the pros attached to the process it only establishes the abnormal chromosomes but it can’t identify why they become abnormal or what makes them abnormal.

In turn this knowledge could increase the success rate even higher and in an area which would need to be explored in full detail to identify the full benefits that could be available.

Doctors need to look at the individual patients who would receive the treatment, whether it would be available to every woman or would it only be available to selected patients.

Also, such a success rate would probably come with a price tag which would beg the question would patients expected to even pay more to benefit from this specialised technique?

It’s very easy to develop a new technique and believe that a few tests represent the real statistics. People assume that this will be a success however, to be sure scientists need to continue doing extensive research to prove its reliability and benefits for the wide majority.

Unfortunately nothing is concrete but it is safe to say that anyone who has experienced IVF treatment would welcome any increase in success rate with open arms.

Relevant Links

Oxford Biomedical Research

IVF Support