Pre-implantational Genetic Diagnosis

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Preimplantational Genetic Diagnosis (PGD) is the study of chromosomes and genetic alterations in the embryo before the transfer to the mother.

PGD allows us to know which embryos are free from chromosomic abnormalities and genetic mutations. Its aims are to assure healthy offspring and to end up with the transmission of certain pathology.

PGD technique is typified in the Law 14/2006, May 26th, regarding assisted human reproduction techniques.

The first step is an exhaustive research by our geneticists and molecular biologists of every case in particular. Afterwards, the diagnostic strategy for the future embryos is settled.

The couple must undergo an In Vitro Fecundation treatment (IVF). In general, microinjection is the technique chosen for the fecundation of the ovocites. We must wait for three days so that the embryos resulting from the process are divided until the stage of six-eight cells. In this moment the embryo biopsy will take place; however, if this division degree is not achieved, the biopsy is not recommended because it reduces the viability of the embryo. Thanks to the experience of our team and using a micro laser only one cell is extracted (blast mere), so that the future embryo is not damaged and we do not reduce the implantation rate which has already decreased during the biopsy.

The extracted blastomeres will be analysed in the molecular biology laboratory and the biopsed embryos will remain in culture till the achievement of the genetic diagnosis. The goal is to transfer healthy and evolutive embryos that will produce a totally normal gestation.

The current indications are the following:

1. Autosomic hereditary diseases or related to the sexual chromosomes

The number of hereditary diseases in which we know the origin of its anomaly is growing every day. When we detect if the embryo is affected or not, we can assure a healthy offspring and make sure we end up with the transmission of the illness to future generations.

The genetic department of Instituto Bernabeu offers a comprehensive research of the family and maximizes the diagnosis in a faster way than in any other centre.

Our department is a pioneer and it is a worldwide reference in the technique called MDA (Multiple displacement amplification) regarding the Pre-implantational Genetic Diagnosis. The development and practice of this technique solve one of the main limitations that happen in PGD monogenic diseases which is the quantity of DNA available to carry out the diagnosis.

Nowadays the illnesses that we have already diagnosed are:

  • Huntington´s Chorea
  • Fragile X Syndrome
  • Miotonic Distrofy
  • Marfan Syndrome
  • Retinoschisis
  • Hemophilia
  • Fibrosis Quistic
  • Beta Talasemia
  • Hydrocephaly
  • Emery-Dreyffus
  • Incontinence Pigmenti
  • Acute Intermittent Porphyria
  • Adrenoleucodistrophy
  • Spinocerebellar Ataxia 3
  • Duchenne Muscular Dystrophy
  • Hypocalcemic Paralysis
  • Family Angiodema
  • Carney's Syndrome
  • Spinal muscular atrophy type 1
  • Charcot- Marie- Tooth 1
  • Polycystic Kidney Disease

Should you be interested in having more information about any other disease not appearing in the above list, do not hesitate to ask us, since we are constantly designing protocols of PGD for other diseases. That is why this list is constantly growing. The versatility of both the available equipments in the Genetic department and of our staff allows to carry out different family researches relating to other hereditary illnesses. In this way, we offer a service personalized to each patient.

2. Structural chromosomal alterations

Suffering structural chromosomal alterations (translocations, inversions…) which are balanced does not have clinical repercussions. The importance of being a carrier of a balanced structural alteration is that the oocytes or spermatozoids produced can have a chromosomal imbalance, and therefore the resulting embryo or pregnancy will inherit this imbalance, causing that the embryo does not implant, or that the pregnancy is lost or that the child is born with physical and/or mental disorders. Patients having this kind of alterations may have multiple miscarriages or may have children with lethal syndromes. Using P.G.D through FISH technique and using specific catheters for the chromosomes implied in the alterations, allows the selection of embryos that lack imbalances, obtaining then a successful evolutionary pregnancy.

3. Repetitive miscarriages

It is considered that in 50% of the repetition miscarriage cases, the cause is in the embryo and not in the couple.

An anomalous number or an altered structure of the chromosomes of the embryo is one of the explanations for many repetition miscarriage cases. PGD, by means of FISH technique, allows toselect the embryos free from these structural and numerical anomalies (analysis of 9 chromosomes X, Y, 13, 15, 16, 17, 18, 21, 22) and then achieving an evolutive pregnancy.

4. Previous failures in IVF

Sometimes, the embryos transferred in an IVF cycle may be apparently normal, but they can have chromosome disorders that are not diagnosed in a conventional IVF and that explain the implantation failure.

In the above mentioned cases, PGD is especially important because it allows a more accurate embryo selection and also to guide about the convenience to continue or start other treatments or not.

5. Advanced age women

There are evidence of an increase of aneuploide rates in gestations of advanced age women. Thanks to PGD we can avoid the transfer of those embryos that are morphologically normal that could be chromosomically altered.

6. Researches of chromosome segregation altered in spermatozoids (FISH or meiosis)

The male factor is one of the causes of high degree aneuploide in the embryo. Previous genetic researches of the spermatozoids with an alterated result indicate a bigger risk in the achievement of aneuploide embryos. DGP, as in the above mentioned cases, allows us to distinguish between the chromosomically altered embryos and the normal ones.

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