faq

The Preimplantation Genetic Diagnosis (PGD) comprises a series of techniques that allow to diagnose a determined genetic condition in embryonic cells. Its final purpose is to prevent severe genetic disease transmission to their descendants so that the couple can have a healthy child.

The PGD represents the only alternative of Prenatal Diagnosis  to the couples  who are carriers of genetic alterations.

The PGD is indicated for couples who are carriers of structural chromosomal alterations (translocations, inversions) and for couples who are carriers of severe genetic diseases and are at risk of transmitting it to their descendants.

It is also indicated for couples with reproductive problems, the Preimplantation Genetic Diagnosis of Screening for Aneuploidy (CCS). Principally for those couples who have recurrent miscarriages of unknown aetiology, as well as implantation failure, advanced maternal age or severe male factor. This type of diagnosis intends to detect alterations at the chromosomal embryo level that can compromise its viability.

The genetic disease has to be severe, of early appearance, and not susceptible to postnatal healing treatment.
The PGD is performed on embryonic cells, thus it is necessary to recur to in vitro Fertilisation (IVF) to be able to access to the embryo and to carry out the cell biopsy. Once it has been extracted, the cell is analysed to search chromosomal alterations or severe genetic diseases, selecting those healthy embryos  or chromosomally normal before the transfer to the mother´s uterus, and therefore before the implantation has been performed.

After the ovulation induction treatment, the patient is subjected to the follicular puncture, with the aim of getting the ovules. On the same day ( day 0 of the culture) the insemination with the spermatozoa of the couple is carried out. From that moment we have 5 days of embryonic culture.  On the day + 3 of the culture the embryonic puncture is performed. The time for the genetic diagnosis starts counting, which lasts between 24 to 48 hours since the biopsy. Meanwhile the embryos remain in culture in the IVF centre. The transfer of the selected embryos is therefore performed on day +4 or day +5 of the culture.

The biopsy does not compromise the viability of the embryo as it is carried out on a very early evolution stage (6-8 cells), in which the embryonic cells have not been  differentiated yet, or are not specialized. Besides, in Geniality the technique is carried out by highly qualified staff  and with a widespread experience.
The diagnosis is done in a period of 24 to 48 hours with the objective of not having to freeze the embryos and be able to transfer those selected as the healthy ones to the mother´s uterus in the same cycle of IVF.
No, it is not possible to perform a PGD to choose the sex of the future baby, only when it is indicated for a genetic disease bound to the sex, can sex-selection be performed.
The consultation on RGC is the process of communication, in which the couple or patient have the opportunity of solving all their doubts and to be informed of all the stages of the Pre-implantation Genetic Diagnosis. It is very important that a qualified in genetics expert is involved in this process, who can objectively inform the couple about the risk of occurrence (risk of appearance) or recurrence (risk of repetition) of an alteration of genetic origin in their progeny, the evolution of this, treatments and future complications.

Along the process the background of both familial branches will be rebuilt through a genealogical tree, to analyse the type of heredity, detect carriers, and determine the appropriateness of the PGD.

The objective of the RGC is to evaluate the risk, determination of the patron of heredity and appropriate genetic counselling, helping the couple to make their decisions freely and responsibly and to answer all their questions.

It is the study done before the PGD on monogenetic diseases and structural chromosomal alterations. This study is carried out with a small sample of blood of the progenitors or future parents and generally, the participation of other members of the family will be necessary, future grandparents or aunts and uncles; with the objective of designing the diagnosis that will later be carried out in the embryonic cells. The diagnosis is always personalised for each family. Once this study has been concluded, the couple can start the cycle of in vitro fertilisation for the PGD.
No, our centre is specialized on Preimplantation Genetic Diagnosis, so the couple is free to choose the IVF centre in any place of the national territory. Our staff will go to the IVF centre to perform the embryonic biopsy and the genetic diagnosis will be carried out in our facilities. If it is necessary, Geniality can orientate on the election of the IVF centre.
Spanish Law limits the number of embryos to a maximum of three. There exit several clinic criteria to determine the number of embryos to transfer, which are among others, the age of the patient, the answer to the IVF treatment and the embryonic quality. However, when a Preimplantation Genetic Diagnosis is done, the number of embryos to transfer will mainly depend on the result of the diagnosis and the embryonic evolution.
We have to take into account that when a PGD is done, we are able to select healthy embryos but we also select those that are not. If we have more than three healthy and evolutionary embryos they can be criopreserved in the authorised banks of the IVF centres have, as the couple could recur to them in future cycles.

Regarding the embryos with the diagnosis of affect, the options are to donate the embryos with the purpose of investigation or stop their preservation.

The trustworthiness of the result of the PGD makes Prenatal Diagnosis not be necessary. However, it is advisable because the Prenatal Diagnosis provides additional information to the one obtained with the PGD. (e.g. the total amount of chromosomes of the embryo), and at the same time it can confirm the results obtained.
The Law that regulates these techniques is the Law 14/2006 of 26 May, about assisted human reproduction techniques, which can be consulted on the Internet.
If there were more than three healthy and evolutionary embryos they could be criopreserved in the authorised banks of the IFV, as the couple could recur to them in future cycles. Regarding the embryos with the diagnosis of affect, the couple will be able to decide about its destiny through informed consent to the IVF centre.
Yes, there are cases such as the PGD for the selection of the HLA (Human Leukocyte Antigen) with therapeutic purposes to others who require a favourable inform from the National Commission on Assisted Human Reproduction. It also occurs in cases of PGD for hereditary cancer predisposition syndrome or severe genetic diseases with variable penetrance.
It is the most appropriate technique for couples who have suffered from recurrent miscarriages without any known aetiology, or couples who after several processes of IVF cannot get a desired pregnancy. In these cases the existence of some chromosomal alterations at the embryo level is presumed, which is known with the name of aneploudy (loss or gain of chromosomes), becoming a common technique in the most specialised and exceptional Assisted Reproduction Centers.

It is also the suitable technique for couples who are carriers of structural chromosomal alterations in their karyotype (reciprocal or robertsonian translocations; inversions).

This is the study of the chromosomes that are contained in a cell, in a normal karyotype we can find 22 pairs of autosomal chromosomes, and a pair of different chromosomes depending on the sex of the individual, the sex chromosomes, XX (girl) or XY (boy), in total 23 pairs or 46 chromosomes. Half of them are inherited from our mother (22+X) and the other half from our father (22+ X or 22+ Y).
An aneuploidy is what we observe in a cell when we find a numeric anomaly in the karyotype, that is to say that in the 22 pairs of autosomas or in the pair of sex chromosomes we find missing or extra chromosomes. For instance, people with Down Syndrome have three chromosomes 21 (trisomy 21), in total 47 chromosomes.
Certainly, most part of aneuploidies, make the embryo fail to implant in the uterus or if they do they can produce early miscarriages or in the worst cases children with severe malformations; other aneuploidies, such as Down Syndrome are compatible with life.
It is known that they are produced in the gametes (ovules or spermatozoa) and also during the first stages of embryonic division. It is shown that there is an increase in the rate of aneuploid ovules with female aging. We can say that approximately 70% of the embryos of advanced maternal age women (older than 37 years old) obtained with in vitro Fertilisation techniques and 50% of their blastocysts (Fig. 1.B) are chromosomally abnormal (aneuploid). This abnormality contributes in general to the low rates of implantation and high rates of miscarriage that increase in a natural way with female aging.
Until a few years ago this genetic study was carried out through FISH technique (Fluorescence In Situ Hybridization). This technique could only allow to analyze a limited number of chromosomes in the biopsied cell, which varied between 5 to 12 from the total 23 pairs of chromosomes that human species has, so a great part of the embryo chromosomes remained without being analysed. The `normal´ embryos from the analyzed chromosomes  and those of better morphology were selected for the transfer to the uterus. However, the results obtained so far were not unanimous for the different clinic indications, and, in general, it was observed that the rate of pregnancy or the rate of baby born did not increase, as it was to be expected.

From 2009 the analysis of embryonic cells started to be used, Array technique of Comparative Genomic Hybridization (CGH). Array CGH is a technique for genetic analysis, which detects  losses or gains of the genomic regions that can appear in a sample of DNA in a global way, that is, it studies the whole genome at the same time, without selection or bias. The Array CGH helps us to solve the limitations of FISH, becoming a powerful tool that permits a trustworthy analysis of the 23 pairs of chromosomes. In the last years similar techniques to Array CGH have been emerging, for example, the KaryoLite BoBs, which allows us to analyse the chromosomes at a high resolution and in an automatic way.

  • It allows a whole chromosomal analysis (23/23 chromosomes) of the biopsied cell,  permitting that way to select the diploid and healthy embryos for the transfer to the uterus.
  • The analysis is performed at a high resolution and in an automatic way, and the interpretation of the results are made by computer software.
  • It improves the rate of birth per embryo transferred in vitro Fertilisation.
  • It minimizes the incident of spontaneous miscarriages and children with malformations caused by the irregularity in the number of chromosomes (such as Down Syndrome, Edwards Syndrome or Patau Syndrome)
  • It permits to detect unbalanced translocations and other chromosomal alterations, being a fundamental diagnostic tool for couples who are carriers of structural alterations in the karyotype.
  • It reduces the incidence of multiple pregnancy, permitting the transfer of an only embryo maintaining a high rate of born alive.
No, this technique only detects losses or gains of chromosomal regions, which will cause the embryo not to be viable, the pregnancy not to be produced, or cause an early miscarriage.
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