Preimplantation Genetic Testing

Here at Sistemas Genómicos, we are currently the only Spanish laboratory that has been certified for PGT: we offer a PGT programme aimed at IVF centres with the maximum level of guarantees and the best technology.

This technique is carried out on human embryos created using in vitro fertilisation techniques, under the strictest bioethics and legal guidelines. A biopsy is carried out on the embryos in order to analyse whether or not there are any specific genetic mutations, allowing us to select an embryo that does not have the genetic disease under analysis.

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PGT

PGT is a genetic diagnostic method combined with in vitro fertilisation techniques aimed at preventing the transmission of genetic and hereditary diseases to children.

It is conducted on human embryos created using in vitro fertilisation techniques. A biopsy is carried out on the embryos using micromanipulation techniques. The biopsy can be carried out on third day of the culture (D3) or at later stages on the blastocyst (D5). The biopsy on D3 allows us to get a unique cell, known as the blastomere, while on D5 a biopsy can be carried out on the trophectoderm, a tissue that covers in internal wall of the embryo on D5.

The sample from the biopsy is subject to genetic analysis to find out the genetic status of the embryo it comes from. Lastly, the embryo without the disease is transferred to the mother’s womb, thus preventing transmission.

Blastomere (D3)

Trophectoderm (D5)

In the Reproductive Genetics Unit, we offer a PGT programme aimed at IVF centres with the highest level of guarantees and the top diagnosis technology.

Sistemas Genómicos sets itself apart with its constant investment and commitment to quality. Along these lines, in October 2006, the Spanish Association for Standardisation and Certification (AENOR) awarded our PGT services with UNE-EN ISO 9001:2008 certification (ER 0052-2005), making us the first laboratory in Spain to be certified for PGT services.

In October 2012, the Spanish National Accreditation Agency (ENAC) granted UNE-EN ISO 15189: 2007 (CGA-ENAC-LCL) certification to the genetic informativity and preimplantation genetic diagnosis study for Huntington’s disease, Steinert myotonic dystrophy and fragile X syndrome.   Furthermore, in June 2013, we widened our scope to cover all monogenic diseases and in June 2014, we were awarded accreditation for our trophectoderm sample type.

We are currently the only laboratory in Spain with accreditations for PGT.

The PGT laboratory also participates in annual CEQA and UKNEQAS peer reviews for FISH PGD, monogenic disease PGT and PGT for detecting aneuploidies and/or structural chromosomes abnormalities.

WHO IS IT AIMED AT?

 

It is aimed at all couples with a genetic risk; in other words, those who have a family member who is suffering from or is a carrier of any genetic and hereditary disease and who want make sure they have healthy children. It is important to note that the vast majority of these couples are not infertile.

Diseases Analysed

 

In each case we analyse the disease that the couple presents. Specifically, these could be monogenic diseases (dominant, recessive and X-linked), structural chromosome abnormalities (reciprocal translocations, Robertsonian translocations, inversions and other complex rearrangements) or numerical chromosome abnormalities (Turner syndrome, Klinefelter syndrome, etc.).

Regarding the PGT for monogenic diseases, we can conduct it for all of the monogenic diseases that have an identified cause (https://omim.org/). In other words, we need to identify the mutation or mutations that cause the disease in order to conduct the PGT.

Steps to follow to conduct a PGT

 

Step 1: Professional Consultation.

Get in touch with us directly on dgp@sistemasgenomicos.com and one of our Genetic experts will give you advice and address your needs with no commitments. To have a proper assessment in the consultation, you will need to send us the genetic reports on the case so that we can come up with the best option for diagnosis in each case, creating a personalised proposal.

If there is no genetic diagnosis for the disease, our Medical Genetics Unit can carry out these studies.

Step2: Informativity Study.

In some cases, it is necessary to carry out an informativity study before the PGT process.

This study is obligatory for:

  • PGT for monogenic disease
  • PGT for monogenic disease combined with a study of aneuploidies and/or structural chromosome abnormalities
  • PGT for monogenic disease combined with a HLA type study
  • PGT for HLA type
  • FISH PGT for structural chromosome abnormalities.

The informativity study is not recommended in the following cases:

  • PGT via massive sequencing for aneuploidies and/or structural chromosome abnormalities
  • FISH PGD for Robertsonian translocations

Step 3: PGT Cycle Scheduling

Get in touch with our PGT department on programacion.dgp@sistemasgenomicos.com when you are ready to start your ovarian stimulation programme to get your case scheduled in and coordinate our laboratory with the IVF cycle.

The information we need to schedule in a cycle is included in the table below, which needs to be filled out and attached to the email when you get in contact with us:

 

PATIENT NAME/CODE 
PGD Method:

  • PGT-A (NGS) *
  • PGT-SR (NGS)*
  • PGT-M (PCR)
  • PGT-COMBINADO (PGT-M+PGT-A)*
  • PGT-A (FISH)
  • PGT-SR (FISH)
 
PGT Indication 
Biopsy(D+3/D+4/D+5) 
Home biopsy (Yes/No) 
Estimated follicular puncture date (day/month/year) 
PGD Results (fresh/deferred) 

Step 4: Embryo biopsy.

Our embryologists can carry out the embryo biopsy in your own laboratory, if you need them to.  What’s more, we can train the embryologists on site at your centre.

Step 5: Analysis.

24 hours after receiving the samples, you will get the results so that you can carry out the embryo transfer in accordance with your laboratory’s criteria.

For deferred transfers, you will get the results within a maximum term of 20 calendar days.

PGT-M (PGT for monogenic diseases)

WHO IS IT AIMED AT?

 

PGT-M is recommended when both members of the couple are asymptomatic carriers of a disease or when one of them is affected by a genetic disease caused by the mutation of a specific gene.

Before carrying out the cycle, it is necessary to carry out a Genetic Informativity Study.

COMPATIBLE EMBRYO SELECTION VIA PGT-M

 

In these cases, the couple is looking to have a child that is a match for their affected child. When they are born, the new child will be a donor for their sick brother or sister using stem cells from their umbilical cord.

Such cases require special authorisation from the Health Authorities of the relevant Regional Government as stipulated in the Assisted Human Reproduction Act 14/2006. Your IVF centre must request authorisation.

The steps to follow are the same as those for a PGT-M for monogenic diseases and what we are analysing in this case is a coding region of the genome that controls immune response, (known as the HLA: Human Leukocyte Antigen).

Diseases that affect the HLA system can be hereditary (but not always). If the parents are carriers of the disease that is affecting their child, PGT allows them to find embryos that are compatible and free from the disease so that their future donor child will be born healthy.

Time frame for conducting a PGT-M

The PGT is carried out in close collaboration with the assisted conception centre.

The complete PGT process includes stages carried out by the Reproductive Genetics Unit (in blue) and the assisted conception centre (in green).

PGT-A (PGT for aneuploidy)

PGT-A (PGT for aneuploidy) is a chromosome analysis conducted on embryos in the preimplantation stage. The aim is to select embryos with a normal number of chromosomes for the chromosomes under analysis, detecting aneuploidy; in other words, increases or decreases of one particular chromosome in the embryo.

This does not detect increases or decreases in chromosome fragments or chromosome rearrangements. The transfer of an aneuploid embryo can reduce the conception rate and increase the percentage of spontaneous miscarriage.

Who is it aimed at?

 

It is aimed at couples who use an IVF clinic due to infertility without any family history of hereditary diseases. The established recommendations are:

  • Couples who have suffered repeated miscarriages, normal karyotypes and trombophillia screening.
  • Couples with successive failed attempts after using assisted conception techniques.
  • Women of a late reproductive age.
  • Couples with previous aneuploid conceptions.
  • Men with high aneuploidy levels in their sperm.

diseases analysed

 

Due to the nature of the study, no specific disease is studied. The number of chromosomes is analysed. An abnormal number of one or more chromosomes is directly linked to miscarriages in the situations listed above.

Timeframe for conducting a PGT-A

The process is simpler than that of other PGT. It is directly scheduled in with the IVF process.

Complete process for massive sequencing cases

PGT-SR Structural Chromosome Abnormalities

Analysis of structural chromosome abnormalities diagnosed in parents-to-be by karyotype.

WHO IS IT AIMED AT?

 

Couples that are carriers of structural chromosome abnormalities (such as reciprocal translocations, Robertsonian translocations or inversions) can generate abnormal embryos and, in some cases, have problems with infertility and/or subfertility. In these cases, we conduct the PGT-SR for any kind of chromosome anomalies that have been diagnosed in either of the parents by karyotype.

Diagnosis Options

There are two diagnosis options: FISH (fluorescent in situ hybridization) and mass sequencing.

The FISH technique only allows for the analysis of the chromosomes involved in the anomaly under analysis and requires a prior informativity study.

Massive sequencing study all of the chromosomes and do not require a prior informativity study. 

Structural Chromosome Anomalies Study

 

In most cases of PGT-SR with Structural Chromosome Anomalies, this is carried out using  massive sequencing techniques.

Occasionally, when the unbalanced pattern of structural rearrangement of which either member of the couple is a carrier is lower than 20 Mb, it will be necessary to study it using the FISH technique.

Our genetics experts will assess which type of technique is best for each specific case.

Timeframe for Structural Chromosome Anomalies PG-sr

Complete process for massive sequencing cases

Combined PGT

Who is it aimed at?

 

Combined PGT is intended for any couple in which both members are asymptomatic carriers of a disease or if one of them is affected by a genetic disease. Furthermore, sometimes there is more than one clinical indication for the same couple.

The most common case is when a couple is a carrier of a monogenic disease and one of the indications for PGT-A: advanced age of the mother, abnormal sperm FISH, etc. In other cases, which are much less frequent, there is more than one disease present in the couple, for example when one partner has an abnormal karyotype as well as a monogenic disease.

Before carrying out the cycle, it is necessary to carry out a Genetic Informativity Study.

Study with various indications in the same sample

 

With Combined PGT we can study various monogenic diseases, aneuploidies or structural chromosome anomalies and we can even select which embryos are most histocompatible with a sick brother. All in just one embryo biopsy.

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Combined PGT timeframe

The best strategy is to analyse whether the embryos are free of the first monogenic disease and then study the aneuploidies in these embryos. To do this, the embryos must be frozen (vitrification).

Complete process for Combined PGD with an aneuploidy study using massive sequencing

Accreditations

 

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