PGD

What is Preimplantation Genetic Diagnosis (PGD)

Preimplantation genetic diagnosis (PGD) is a scientific method which allows to study the genetic characteristics of an embryo before it is transferred to the uterus, in order to prevent your future child from being born with a hereditary disorder.

This technique is useful in couples with high genetic risk and to improve the efficiency of an In Vitro Fertilization process.

The first PGD pregnancy in Spain was achieved in 1994 in our hospital in collaboration with the Universitat Autònoma de Barcelona (UAB) to prevent the conception of a child with haemophilia in a couple where the mother was a carrier of the disease. Since then many couples have benefited from this technique.

In July 2006, our Obstetrics Department together with the Biomedical Division of the company Sistemas Genómicos achieved the first Multiple Hereditary Exostosis-free pregnancy in the world, using the Preimplantation Genetic Diagnosis technique.

What are the phases of the treatment

Price

 

Included:

 

 

Not included:

¹ The medication must be purchased from a pharmacy with the prescriptions provided.
² Embryo cryopreservation is paid in advance for the first 12 months and each year for its annual maintenance.

Who it is for

Preimplantation Genetic Diagnosis is advisable if either you or your partner:

• Have a risk of transmitting a genetic disorder to your offspring.
• Have chromosomal abnormalities.
• Have had repeated miscarriages or repeated implantation failures.
• Have completed IVF cycles without success.
• Have a genetic predisposition for cancer.
• Have a child with a serious disorder requiring a transplant, and need to achieve pregnancy and to deliver a compatible donor.

Monogenic diseases

Monogenic diseases are those caused by a specific gene mutation (cystic fibrosis, thalassemias, fragile X syndrome, etc.). To prevent the transmission of this disease by use of PGD it is essential to know the mutation causing the disease.

The number of the identified monogenic diseases is above 6,000, and many of which could cause severe health disorders. See the list of monogenic diseases analysed with PGD.

If, after a preconceptional genetic test, an increased risk has been detected for the offspring, it is possible to analyse the embryos to avoid future children being affected by the disease in question.

In cases of PGD of monogenic diseases, it is necessary to carry out a study of informativity prior to the PGD cycle to confirm that the diagnosis is feasible and adjust the technique to each case.

Chromosome abnormalities, numerical or structural

The presence of a chromosome reorganisation (Robertsonian translocations, reciprocal translocations and inversions) in one member of the couple may lead to difficulties in conceiving, miscarriages or congenital malformations. The use of PGD in these couples is extremely useful.

Both in the case of monogenic diseases and those associated with chromosomal reorganisation, it is necessary to conduct a genetic informativity study before the PGD cycle to confirm that the diagnosis is reliable and to adjust the technique to each individual case.

It is also indicated in cases of numerical chromosome abnormalities, pure or mosaic.

Couple coming from IVF programmes

The main cause of absence of pregnancy after a cycle of In Vitro Fertilization is the presence of chromosomal abnormalities in the transferred embryos. In the same way, the majority of first trimester miscarriages are caused by the implantation of an embryo with some chromosomal anomaly.

The Preimplantation Genetic Diagnosis allows to complement an In Vitro Fertilization process, identifying embryos with alterations in the number of chromosomes and discarding them for the transfer. Only euploid embryos or with a normal chromosomal envelope are transferred. With this selection, it is possible to reduce the time to get a pregnancy and it reduces the chances of miscarriage and of conception affected by chromosomopathies.

There are certain factors that can predispose to an increased production of embryos with alterations in the number of chromosomes. In these cases, performing a PGD is especially beneficial:

• Advance maternal age (>37 years).
• Altered male meiosis.
• Couples with repeated miscarriage.
• Couples with repeated implantation failures.

Other indications

Predisposition to certain diseases

It is known that mutations of some gene predispose individuals to certain diseases that may appear at different life stages, such as neurofibromatosis, familial adenomatous polyposis or genetic breast cancer (BRCA1, BRCA2), etc.

When a hereditary disease component is confirmed, the possibility of PGD would allow the possible appearance of this disease in the next generation to be avoided.

In some of these cases, the express authorisation from the Health Authority is necessary in order to conduct PGD, following a favourable report of the National Commission of Human Assisted Reproduction which assesses the particular social, therapeutic and clinical characteristics.

PGD-HLA

The current law governing assisted reproduction techniques (Law 14/2006) considers the possibility of conducting a PGD cycle to determine the histocompatibility antigens for therapeutic purposes for third parties. This is used when a first-degree relative, generally a child, suffers from a serious hematopoietic disease that requires the transplant of histocompatible bone marrow or umbilical cord cells.

In order to conduct PGD-HLA, express authorisation from the corresponding Health Authority with a prior favourable ruling from National Commission of Human Assisted Reproduction which evaluates the social, therapeutic and clinical characteristics of each case.

The first child born after the application of PGD-HLA was in the USA in 2000. This permitted the successful donation of umbilical cord cells to his sister who had Fanconi anaemia.

List of monogenic diseases

The number of the identified monogenic diseases is above 6,000, and many of which could cause severe health disorders.

List of monogenic diseases analysed with PGD:

• Achondroplasia
• Adrenoleukodystrophy
• Alpha thalassaemia
• Alpha-1-antitrypsin deficiency
• Alport syndrome
• Amyotrophic lateral sclerosis
• Beta thalassemia
• Charcot-Marie-Tooth
• Congenital disorder of glycosylation type 1a
• Crouzon syndrome
• Cystic fibrosis
• Duchenne and Becker muscular dystrophy
• Dystonia 1, Torsion
• Emery-Dreifuss muscular dystrophy
• Facioscapulohumeral dystrophy
• Familial adenomatous polyposis
• Familial amyloidotic polyneuropathy
• Familial dysautonomia
• Fanconi anaemia
• Fragile X
• Glutaric aciduria type 1
• Haemophilia A and B
• Hemophagocytic lymphohistiocytosis
• Holt-Oram syndrome
• Huntington’s disease
• Hyperinsulinemic hypoglycemia
• Hypokalaemic periodic paralysis
• Incontinentia pigmenti
• Lynch syndrome
• Marfan syndrome
• Menkes disease
• Metachromatic leukodystrophy
• Mucopolysaccharidosis type II (Hunter syndrome)
• Multiple endocrine neoplasia (MEN2)
• Multiple exostosis
• Myotonic dystrophy
• Neurofibromatosis type I and II
• Non-syndromic Sensorineural Deafness
• Norrie syndrome
• Osteogenesis imperfecta (brittle bone disease)
• Polycystic kidney, autosomal dominant
• Polycystic kidney, autosomal recessive
• Pompe’s syndrome
• Sickle cell anaemia
• Smith-Lemli-Opitz syndrome
• Spastic paraplegia 4
• Spinal and bulbar muscular atrophy
• Spinal muscular atrophy
• Spinocerebellar ataxia 1, 2 and 3
• Spondylometaphyseal dysplasia (Schmidt)
• Tay-Sachs disease
• Treacher Collins
• Tuberous sclerosis
• Von Hippel-Lindau syndrome

Performing a PGD cycle for these diseases does not require the express authorization of the health authorities.

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