Indications

This technique is useful in couples who have a high risk of passing on certain genetic diseases or chromosome mutations to their children. It is also indicated in some couples coming from an IVF programme.

Couples with a high genetic risk

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.

If a family has a disease associated with X chromosome but the specific gene alteration is not known, PGD can be conducted by means of gender selection. Gender selection for social reasons is prohibited in Spain.

See Annex with a list of monogenic diseases analysed with PGD in accordance with the European Society for Human Reproduction and Embryology (ESHRE Consortium).

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.

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

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.

Couple coming from IVF programmes

In this case, PGD permits the screening for chromosomes most commonly involved in prenatal abnormalities and miscarriages during the first trimester. The aim is to improve rates of live home births by means of increased implantation rates and a reduction in number of miscarriages and conceptions with chromosomal diseases.

This may be indicated in various situations such as:

  • 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.

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