Preimplantational genetic diagnosis |
The Preimplantation Genetic Diagnosis (PGD) is a diagnostic technique, carried out under an IVF treatment, which allows us to study the embryos genetically and chromosomally in order to select the healthiest embryos before the transfer. This technique avoids the pregnancy of a genetically or chromosomally affected child. Therefore, it also avoids taking the hard decision of carrying out a therapeutic abortion.
In Spain, the number of cases in which PGD has been applied has doubled in recent years. In 2005, PGD has been carried out in 20% of the IVF treatments performed in Europe.
According to the Catalan Government IVF Official Registry throughout 2006, the highest rate of “children at home” with Assisted Reproduction techniques was due to Preimplantation Genetic Diagnosis. According to these data, this technique could have diagnosed 30% of serious illnesses compatible with life.
For the first time in the history of Preimplantational Genetic Diagnosis we can study all the chromosomes of the embryo in the same cell through the FISH technique and transfer it at the most advisable moment, five days after fertilization, without necessity of vitrifying or freezing the embryos.This technique, recently presented at the Congress of Fertility in Spanish Society 2010, is already being applied systematically in our PGD laboratory to improve the efficiency of Preimplantational Genetic Diagnosis without added cost for the patient.
More information: www.pgdcem.com
Is it possible to perform a genetic analysis of the embryos before they are transferred to the uterus?
Yes. It is possible to analyze genetically the embryos prior their transfer to the uterus. This technique is called Preimplantational Genetic Diagnosis or Embryo Genetic Analysis.
Does 'Embryo Genetic Analysis' increase pregnancy rate?
Yes, because it avoids the transfer of embryos that contain an abnormal number of chromosomes (aneuploid embryos). Using this procedure, only chromosomally normal embryos with a good morphology are transferred.
Does 'Embryo genetic analysis' decrease the rate of spontaneous miscarriage?
Yes. 'Embryo Genetic Analysis' can significantly reduce spontaneous miscarriage because most of them are due to genetic anomalies.
Does 'Embryo Genetic Analysis' prevent the birth of children with chromosomal abnormalities?
Yes. It can avoid the birth of children with chromosomal abnormalities such as trisomy 21 or Down's syndrome.
How is embryo genetic análisis performed?
In vitro fertilization-derived embryos are cultured until Day 3 of development at which stage embryos have 6 to 8 cells or blastomeres. Then, a hole is made in the zona pellucida (the layer that covers the embryo) and one cell is aspirated using a special micropipette (biopsy procedure). The aspirated cell is processed for genetic analysis while the embryo is mantained in culture. Genetically normal embryos are transferred to the uterus the next day.
Could this technique damage the embryo?
The biopsy procedure is highly sophisticated technique that when performed by experienced embryologists should not negatively affect embryo viability.
Is it posible to prevent a genetic disease using 'Preimplantational Genetic Diagnosis'?
Yes. The group of patients that benefit most from Preimplantational Genetic Diagnosis are couples with a history of a genetic disease. This is so because it allows to transfer normal embryos free of the genetic disease and, therefore, pregnancy termination is avoided. There are two types of monogenic disorders: autosomal disorders such as Cystic frybrosis, Myotonic Distrophy, Huntington's disease or sex-linked disorders as Fragile X Syndrome, Douchenne's Muscular Dystrophy or Hemophilia.
Can patients with a previous spontaneous miscarriage benefit from 'Preimplantational Genetic Diagnosis'?
Yes. They can prevent further pregnancy loss by performing Preimplantational Genetic Diagnosis. It is of paramount importance in the management of infertility couples with an embryo factor.
Can any couple benefit from 'Preimplantational Genetic Diagnosis'?
Yes. Taking into account all the benefits mentioned above, more and more IVF patients choose to perform Preimplantational Genetic Diagnosis. Specially when the future mother is over 37 years of age or had a previous IVF failure.
