DIAGNOSIS - PGD
Cyprus Hope IVF Consultation
Preimplantation Genetic Diagnosis (PGD) is a genetic test procedure and is performed in conjunction with in vitro fertilization (IVF). PGD helps in detecting the genetic abnormalities either at gene level or at chromosome level before implantation thereby avoiding the transfer of genetically affected embryos. We offer PGD for aneuploidy screening and PGD for chromosome translocation. This is the most common type of PGD analysis to test the embryos using a panel of chromosomes that are commonly involved in miscarriages or trisomic pregnancies.
Embryos screened this way may have a higher rate of implantation, lower spontaneous loss and a reduced risk of trisomic offspring (e.g., Down’s syndrome).
What are the stages involved in IVF treatment?
• A normal human cell contains 46 chromosomes or 23 pairs of chromosomes. These chromosomes are string-like structures that reside in the center of each cell or nucleus and carry the genetic information.
• 22 pairs of chromosomes are called autosomes which are same in men and women. The 23rd pair of chromosomes is called sex chromosomes. Women normally have two of the same sex chromosomes, called the X chromosome, while men normally have 2 different sex chromosomes, known as X and Y chromosomes.
• Sperm and eggs contain half of the total number of 46 chromosomes or 23 chromosomes each.
• A normal fertilized embryo is derived by the fusion of 23 chromosomes from eggs and 23 chromosomes from sperm.
• Abnormal cell division in sperm or eggs might result in greater or fewer chromosomes than the normal 23. Therefore, any embryo that is derived from these sperm or eggs will carry extra or missing chromosomes, an abnormal condition referred to as aneuploidy.
• In approximately, 70% of recurrent miscarriages abnormal numbers (aneuploidy) of chromosomes are identified.
• Some of the most common chromosome abnormalities found in miscarriages are trisomy 16 (3 copies of chromosome 16); trisomy for chromosome 22, 21, 15, 18 or 13; triploidy (3 copies of all the chromosomes); and abnormalities of the sex chromosomes.
• Chromosomally abnormal embryos usually fail to implant in the uterus and implants may not develop normally or pregnancies can miscarry, in some instances a pregnancy can develop to term and give birth to trisomic babies (e.g., Down’s Syndrome).
• The percentage of chromosomally abnormal embryos that each couple produces varies depending on their clinical status.
• Factors such as advanced maternal age (>35 years), the number of failed IVF cycles, miscarriages during normal conception and quality of sperm all influence the proportion of embryos that are abnormal.
• Any deviation from having 2 copies of each chromosome is considered abnormal. If only one of two chromosomes are identified the embryo is considered monosomy and if 3 chromosomes are identified it is considered trisomy. Both these conditions are abnormal and not suitable for embryo transfer.
• For PGD-AS The embryos created by IVF are cultured in the laboratory for 3 days to grow ideally to an 8-cell stage. At that point one or two cells are removed by making a hole on the outer shell of the embryo. This procedure is called embryo biopsy. The biopsied embryo is returned back to culture until the result for that cell/cells are obtained usually on 5th day after egg retrieval.
• Removal of one or two cells from an eight cell embryo does not compromise the embryonic development.
• It is important that the embryo to be biopsied should be at least 5-cell and minimal fragmentation on the 3rd day of embryonic development. If the embryo contains too few cells, a biopsy might jeopardize the viability of the embryo.
• The nuclear material from the biopsied cell is sent to a reference lab. The reference lab performs a procedure called Fluorescent in situ hybridization (FISH) to determine the chromosome status of each cell.
• Our reference lab uses a mixture of FISH probes in one or two sequential hybridizations. Possible chromosomes to be tested include 13, 15, 16, 18, 21, 22, X and Y. Abnormalities in these chromosomes are found commonly in miscarriages and abnormal live births.
• A normal cell should show 2 copies of FISH signals for each of the numbered chromosomes (13, 18 and 21), and either 2X signals for females or 1X and 1Y signals for males.
• There may be situations where the result cannot be obtained or is incorrect. Some of these situations include:
- If the cell is lost during fixation or nucleus is ruptured no result will be obtained.
- Occasionally the chromosomes in the nucleus might not have spread properly and are lying on top of each other which would underestimate the number of chromosomes and might lead to a false result.
- The FISH probe may fail to bind to a chromosome suggesting a missing chromosome.
- If embryo biopsy happens when a particular cell is in the middle of cell division then the result appears to be two nuclei and four sets of chromosomes, FISH analysis from these cells can be difficult to interpret.
• A number of factors influence the success of a PGD/IVF cycle. Current data suggests that PGD cycles are most successful when 8 or more embryos are created by IVF and at least 5 are of good quality as graded by the embryology lab based on the number of cells, fragmentation and uniformity in cell size.
• PGD usually does not increase the pregnancy rates but it reduces the miscarriages and the incidence of trisomic pregnancies.
• PGD is most successful in the patients who have more than 3 embryos that do not show abnormalities and at least two of them are developed to the blastocyst stage. PGD for single gene mutation: This is indicated for the patients where both partners carry a gene for an autosomal recessive disorder or one partner may carry a gene for a dominant disorder and this increases the risk of conceiving a child with severe genetic disorder, e.g., Duchenne’s muscular dystrophy, Cystic Fibrosis, Tay Sachs etc. Currently this list includes more than fifty disorders. This procedure involves prior testing to detect the gene mutation in the patient and partner so that a gene probe can be produced. There are several possible reasons for failure to achieve a successful identification of the gene or to achieve pregnancy. These include:
• Possible failure to amplify the gene in question or degraded nuclear material that does not allow for a clear DNA signal.
• PGD for single gene mutation can only detect the embryos that are carrying the mutation irrespective of the implantation potential of the embryo. PGD for chromosomal translocation or structural abnormalities: Chromosomal translocations involve a rearrangement of the chromosome material so that some of the genetic material from one chromosome is located on another one. This is known as a “balanced” translocation where all of the normal genetic material is present.
• If one partner carries a balanced chromosome rearrangement, he or she can produce sperm or eggs that can contain an extra or a missing segment of a particular chromosome material. These may produce conceptions which contain “unbalanced” translocation where there is either excess or deficient total genetic material. This can result in failed early embryonic development, recurrent pregnancy loss or birth of a child with mental and/or physical defects.
• Not all translocations or structural rearrangements can be tested by PGD. The reference lab would need to analyse the karyotype from the blood of both partners prior to start the IVF cycles to check the feasibility of performing the PGD for that anomaly.
• Although medical evidence shows that PGD in couples who carry chromosomal translocations helps in reducing pregnancy loss, it cannot eliminate the risk of miscarriages due to other factors.
• PGD for translocation can be carried out in conjunction with aneuploidy screening using the limited number of FISH probes.
This is one of the more important questions that couples are faced with. When researching online for treatment you are faced with many alternatives, but the most important for any treatment is the support provided by the team, this also includes the experience of the Doctor and Embryologists.
Your doctor needs to plan the best treatment for you for optimum eggs number and quality and the embryologists need to be very skilled as the most important part of treatment is the embryo biopsy with minimum risk to the embryo and to encourage embryo development. And our team are perfect for this.
Yes, although the chances of success is based on egg age and sperm quality, carrying out PGD also increase the chances of implantation.
Yes. Stimulation medication is needed to stimulate the antral follicles and encourage them to grow. Once the follicles are of a certain size, the eggs are collected and then sperm is injected into the mature egg for fertilisation.
No. The FISH method screens for chromosomes 13, 18, 21, X and Y and the results of this testing method, advises which embryo is carrying the correct number of the above listed chromosomes. The results of the genetic testing are 99.9% accurate and the results can help to reduce the chances of a baby being born with a chromosomal defect.
What is the procedure for IVF with PGD?
STAGE 1: Stimulation of the Ovaries with Hormones to Produce Egg
To maximise the chance of a successful pregnancy we need to transfer up to two embryos into the womb, which in turn normally requires around four to eight embryos to have been cultivated. To achieve this number of embryos, our scientific team would aim to collect 10 oocytes. This means that we need to stimulate the female’s ovaries to produce many more than the usual single oocyte, and we do this by means of hormonal stimulation of the ovaries, using drugs which mimic the hormones you naturally produce.
These hormones are given to you both as an oral medication and an injection under the skin on the tummy. A detailed treatment schedule indicating the dates and medication to be used will be given to you when the treatment starts. This of course will be designed taking your travel and period dates into account.
Femara Oral Medication
This medication is taken from day 2 or 3 of your menstrual cycle for 5 days inclusively along with the FSH and LH injections.
In some patients, there may be temporary side effects from this medication. The potential side effects are hot flushes, night sweats and mood swings and possible headaches.
FSH and LH Injections
Follicle Stimulating Hormone (FSH) and Luteinizing hormone (LH) injections are given to you as a daily injection over 9 to 11 days to stimulate follicle development in the ovaries. You can find a video guide on You Tube to prepare and self-administer the injections.
We will explain the potential side-effects of these injections and monitor your response of how your follicles are developing using internal scans. The first scan is usually done 4 or 5 days after starting the injections. If you are not able to be here in Cyprus for the first scan then these scans can be carried out in a scanning unit and you can send the reports along with the images to us via email.
Deciding the Day of Your Egg Collection
Based on your final scan and blood tests Dr Zehra will decide the best day for your egg collection. The cycle may be cancelled before egg collection if you do not respond to the medication.
33-35 hours before the egg collection, an injection(s) of hCG hormone is given as a ‘one off’ injection. This medication causes the final stages of egg maturing and ovulation to take place. The time you need to give yourself this injection at home is very important and will be explained very clearly to you.
STAGE 2: Collection of Eggs from the Ovaries
You are deeply sedated and monitored throughout the egg collection procedure, which usually takes about 20 minutes. Using an ultrasound probe to guide, a fine needle is passed inside the vagina and through the vaginal wall into each follicle, until we have emptied all the follicles in one ovary. The needle is then removed and the procedure is repeated in the other ovary.
Each egg is placed in special fluid and transferred to an incubator. Not every follicle will contain an egg and sometimes no eggs will be found during an egg collection. We will discuss this with you before the procedure.
After the procedure you will rest on a bed in your private room for about one or two hours. You will be prescribed the hormone progesterone following the egg collection to help the lining of your uterus be as receptive as possible to the embryos.
STAGE 3: Insemination / Injection of Sperm
Your semen sample is prepared by separating the normal and active sperm from the ejaculated fluid. Fertilisation during pre-implantation genetic diagnosis (PGD) treatment will be done by Intracytoplasmic Sperm Injection (ICSI). ICSI involves injecting a single sperm into the centre of each egg to help achieve fertilisation.
STAGE 4: Fertilisation
The morning after injection / insemination of the sperm, the embryologist carefully examines each egg to see if fertilisation has occurred. We will then contact you to tell you how many eggs have fertilised.
Rarely, about one in 100 times, none of the eggs fertilise and there are no embryos to be replaced. This is obviously very disappointing. We will offer you the earliest available appointment to see doctor Zehra to discuss your cycle.
STAGE 5: Embryo Biopsy
Three days after fertilisation the embryos will usually have reached the stage of development where genetic testing can take place, normally involving a complex and expensive scientific process called Pre-implantation Genetic Diagnosis (PGD, FISH Technique). This involves removing one or two cells from each embryo and analysing the chromosomes in carefully controlled laboratory conditions, during which the ‘X’ and ‘Y’ chromosomes are clearly identified. The removal of up to two cells does not damage the embryo’s development in any way, and each embryo will continue to grow normally.
Our aim is to reach this stage with a minimum of two good, healthy embryos of the chosen sex available for the fourth and final stage of your treatment – the transfer of the embryos to the female’s uterus. The types of tests we perform on the embryos will depend upon the reason behind you having PGD. Apart from sex selection, we are able to screen for any genetic disease that can be tested for. The chromosomes screened are 13, 18, 21, X and Y.
STAGE 6: Embryo Transfer
During embryo transfer we place the best quality embryos into your uterus. This is a much simpler procedure than egg collection and there is no need for an anaesthetic. Ultrasound scan is used through your tummy to help us to transfer the embryos where they would have the highest chance of implanting. A speculum, which is the instrument also used during a smear test, is placed in your vagina to clearly see your cervix (neck of the womb). The outside of your cervix is cleaned and any mucus from inside your cervical canal is removed. This mucus might prevent the embryos getting to where we want them to be in the womb.
The soft catheter, which holds the embryo(s), is inserted the neck of your womb. When we are happy that the catheter is in the best position, the embryos are gently dropped off. The catheter is then removed and checked to make sure all of the embryo(s) have been replaced. This process takes about 5 minutes. It is generally painless although some discomfort comes from the scan probe that pushes down on your bladder which needs to be full for the procedure as well as the speculum in the vagina.
Q: Can sperm that has been frozen be used in an IVF cycle with PGD?
A: Yes. If couples are not able to travel together for treatment at the same time, then sperm can be frozen and stored for use at a later date.
Q: Can PGD be used with a standard In Vitro Fertilisation treatment?
A: Yes. Couples with repeated IVF failures, miscarriages and also known genetic illnesses, IVF with Genetic testing can be used to help transfer the embryos with no chromosomal defects to increase the chances of a pregnancy.
Q: Where can I get more information and begin treatment?
A: By simply calling us on +905488684500, this number is also active on Whatsapp and you can leave a message for us to call you at a time that suits you.
The cost of ICSI (Own Eggs and Sperm) with PGD (FISH) Genetic testing starts from 5,750 Euros and this includes:
- Preimplantation Genetic Diagnosis
Cyprus Hope IVF Consultation