Infertility affects around 10-15 % of couples and the incidence is much higher in females with advanced age of more than 35 years ( >25%). Also the causes of infertility are different in a couple with advanced age of female partner as compared with a young couple. It is a well known fact that female infertility declines with age and chances of miscarriage are also increased in a women with advanced age. The most important reason for this is the embryonic defects which is mainly due to the defective oocyte quality. So to help these group of patients in achieving a successful pregnancy, we can offer them this newer technology of preimplantation genetic screening. This technique is also a boon for the couples with recurrent IVF failures and recurrent abortions.
Whom to offer β This technique can be offered to patients with following issues
1) Couples with advanced age of female partner (>35 years)
2) Couples with recurrent abortions.
3) Either of the partner is suffering from any single gene disorder or any chromosomal disorder.
4) Patients with recurrent ivf failures.
5) Couples with a previous child affected by any genetic disease.
This procedure needs technical expertise and needs to be done by an embryologist who is skilled enough to carry out the procedure. The couple undergoes an ivf cycle and the resultant embryos are then subjected to biopsy. This can be done on either a day 3 embryo ( 8-cell stage), or a day 5 embryo ( blastocyst stage), however biopsy done at blastocyst stage is preferred. So the technique involves creating a small hole in the outer covering of an embryo ( also known as zona pellucida) with the help of non-contact laser, followed by a biopsy of 1-2 blastomeres from a day 3 embryo or 8 to 10 cells from the trophoectoderm layer of a day 5 embryo.
These cells then undergo genetic analysis either using a FISH technique ( 5 chromosomes including no 13,18,21 X and Y) or CGH array ( entire 23 pair of chromosomes are checked). Since it takes some 10 to 15 days for the results to come, so we need to freeze all embryos followed by the transfer of a genetically normal embryo in the next cycle.
This technique is definitely advantageous for those couples with advanced age because it has been observed that as many as 50 percent of grade 1 embryos might not be genetically normal, so when we select them according to their ploidy status, we can improve the ivf outcome and can give them a healthy pregnancy.
Also the patient can go for a single embryo transfer without compromising the success and hence we can reduce the burden of multiple pregnancy and the complications associated with it.
PGT-A
This type of PGT identifies chromosomal abnormalities. Each parent contributes their biological material resulting in 23 chromosomes from each (46 chromosomes or 23 pairs). If the embryo cell is missing a chromosome or there is an extra chromosome itβs called aneuploidy, the βAβ in βPGT-Aβ. A missing chromosome is monosomy, and an additional chromosome is trisomy.
Aneuploidy is one of the leading causes of miscarriage and failed IVF. An embryo can only survive one type of monosomy. Turnerβs syndrome which is the absence of one of the X chromosomes. Trisomy may result in a live birth however the baby may have Down syndrome or the more devastating pate syndrome or Edward syndrome in which the baby only survives a short time.
PGT-M
This test looks for a known gene mutation which the biological parent carries. A family history of a genetic condition provides the cause for PGT-M. When a genetic disorder involves a single specific gene itβs due to a mutation in the DNA sequence. Some of these gene mutations cause cystic fibrosis or sickle cell disorder. Some genes identify a high risk for developing certain cancers such as breast or ovarian cancers (BRCA-1 or BRCA-2). Other common gene mutations discovered via PGT-M:
PGT-SR
Doctors refer to this testing as PGT-SR because the SR stands for structural rearrangements. Biological parents with a known structural rearrangement have inverted or translocated chromosomes. These individuals produce embryos without the correct amount of chromosomal material. That results in loss of the pregnancy. Your doctor recommends PGT-SR if youβve experienced multiple miscarriages.
If your test reveals a structural rearrangement, you may benefit from donor eggs or sperm.
Non-invasive chromosomal screening (NICS) is a breakthrough emerging technology in fertility industry. NICS enables us to identify genetically normal embryos to be transferred into the motherβs uterus (womb) and most importantly – without needing an embryo biopsy. By doing so, we avoid unnecessary embryo transfers with genetically abnormal embryos. This indirectly increases success rate of the IVF cycle. In summary – it reduces the time to pregnancy.
Report can take up to 3-4 weeks.
Report may say
Preimplantation genetic testing for anomalies (PGT-A) is an invasive embryo biopsy procedure which involves taking a biopsy of few cells from Day 5 embryo i.e., the blastocytes.
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