Pre-implantation Diagnosis

What DOES IT CONSIST OF?

Preimplantation Genetic Diagnosis (dpg) detects the presence of the most common genetic and chromosomal alterations in embryos, allowing the baby to be born healthy and free of serious hereditary diseases.

The origin of hereditary diseases is in DNA abnormalities that parents transmit to their offspring, whether they are genetic or chromosomal alterations. The DGP analysis allows detecting them in embryos developed from an assisted reproduction treatment to select only healthy ones.

pgt-a

PGT-A (Preimplantation Genetic Testing for aneuploidy): Allows to detect anomalies in the number of chromosomes (aneuploidies). Normally, a person has 23 pairs of chromosomes, 46 in total. However, sometimes one of these chromosomes has three copies (trisomy) or only one (monosomy), resulting in genetic alterations. Some examples of trisomy are Down syndrome (chromosome 21) or Klinefelter syndrome (an extra X chromosome), which affects only males. On the other hand, among the monosomal alterations we have Turner syndrome, in which a woman has a single X chromosome.

pgt-m

PGT-M (Preimplantation Genetic Testing for monogenics): Monogenic diseases that develop due to the alteration in the genetic information of a particular gene. Thalassemia, haemophilia or cystic fibrosis are included in this group.

This analysis is carried out by means of a biopsy of the blastocyst stage embryos. After this biopsy, the embryos are vitrified pending the results and transferred in a subsequent cryotransfer cycle. Under certain circumstances it is possible not to vitrify them and transfer them fresh.

WHO IS IT FOR?

Embryo graphic

  • Healthy embryos
  • Altered embryos

Age has a negative impact on egg quality, so the older the patient, the higher the percentage of embryos with chromosomal alterations. Therefore, in this group of patients PGD will be more advantageous to exclude altered embryos and increase the chances of pregnancy with a transfer of a healthy embryo.

The main cause of implantation failures and miscarriages are chromosomal alterations in the embryo, so in patients with previous treatment failures, PGD is recommended to obtain more information and increase the chances of success.

In patients with very altered seminal parameters or FISH-type studies of pathological sperm, PGD is also recommended since we may find a higher number of altered embryos than usual.

Patients affected by or carriers of hereditary chromosomal alterations.

  • Faster gestation, since we avoid transferring altered embryos that are unlikely to become pregnant.
  • Decrease the probability of miscarriage
  • Preventing the birth of children with chromosomal disorders
  • Economic advantages. Although this type of analysis can increase the price of treatment at the outset, in many cases the overall cost is lower. The reason is that we avoid the expense of unsuccessful transfers and maintenance of embryos that we would discard directly in case of alterations.

FAQ

FREQUENTLY ASKED QUESTIONS
  • Can PGD guarantee the birth of a completely healthy child?

Nowadays there is no technique that guarantees 100% the health of a child. With the most commonly performed PGD (PGT-A), we can study the alterations in chromosomes (syndromes such as Down, Edwards or Patau), but malformations cannot be ruled out, nor genetic diseases such as cystic fibrosis, muscle dystrophy, thalassemia …

If the patient is a carrier of one of these genetic diseases, with PGT-M this particular disease can be studied in the embryo, but not all the genetic diseases that exist.

  • Can the embryo be damaged by performing a biopsy for the PGD?

The possibility of an embryo degenerating as a result of the biopsy is minimal. The technique is very protocolized and in Ovoclinic we have professionals with the necessary experience.

In addition, the biopsy of the embryo at blastocyst stage has proven to be a safe technique that does not harm the future baby.

  • Can I have healthy children if I have a genetic disease?

Depending on the type of inheritance of the disease there will be a 25% or 50% chance of having an affected child. The way to avoid this would be with DGP.

Firstly, a genetic study will have to be carried out to identify the alteration and the gene responsible for the disease. Subsequently, an informativity study is required. This study helps us to obtain the necessary information to be able to study this alteration in the embryo, and sometimes it requires the participation of patients relatives. The informativity study, once carried out, is used for all the necessary treatment cycles.