Progresul FIV, al tehnologiei biomedicale şi genetice, oferă în acest moment posibilitatea efectuării de analize diagnostice asupra embrionului, încă din primele faze ale dezvoltării acestuia. Diagnosticul genetic de preimplantare (PGD) asigură controlul sănătăţii embrionului înainte ca acesta să fie implantat în uterul femeii, deci înainte de obţinerea unei sarcinii. Datorită acestor analize suntem în măsură să cunoaştem cu exactitate multe dintre caracteristicile fiziologice ale noului organism şi mai mult elemente care ţin de constituţia sa genetică.

Astfel putem să constatăm din timp cauzele genetice responsabile de apariţia multor maladii grave.

Diagnosticul genetic de preimplantare se efectuează în cadrul procedurii de fertilizare în vitro, exclusiv deci la cuplurile supuse fertilizării în vitro, mai concret, atrunci când fertilizarea ovulelor este efectuată prin metoda microfertilizării (metoda ICSI). Embrionii rezultaţi sunt supuşi examenului genetic înainte de a fi transferaţi în uterul femeii. Analitic, în FIV, se face încercarea de fertilizare in vitro (în laborator, în afara corpului uman) a mai multor ovule, pentru ca posibilităţile de a obţine o sarcină să fie crescute. Pentru efectuarea analizei PGD, în primele zile de dezvoltare a ovulelor fecundate rezultate din procedura in vitro, sunt prelevate una sau două celule din totalul de 6 până la 10 din care este constituit embrionul în curs de dezvoltare în stadiul respectiv. Materialul genetic al celulelor prelevate de la ovulele fecundate este supus examinării genetice pentru identificarea anomaliilor cromozomiale dar şi a unor boli genetice monogenice grave. Cu ajutorul analizei PGD pot fi diagnosticate anomalii cromozomiale (sindromul Down, trisomia 13, trispomia 18 şi alte trisomii) precum şi boli monogenice (talasemia a şi b, fibroza chistică, boli dependente de sexul copilului ce se va naşte, boala polichistică renală, etc). Pentru eliminarea greşelilor care au fost rar observate la aplicarea analizei PGD, în ultimii ani este folosită metoda CGH (Comparative Genome Hybridization), care permite compararea cromozomilor analizaţi ai celulei cu cromozomii unei alte celule, a căror componenţă este fiziologică.

To eliminate the errors that are rarely observed during PGD examination, a method known as Comparative Genomic Hybridization (CGH) was developed, allowing for the evaluation of every chromosome in a cell by comparing it to other, healthy chromosomes. CGH can be performed at a later stage, 5-6 days after fertilization (at the blastocyst stage), although it is not generally advisable; this particular technique has been shown in several studies to be detrimental to embryo development. The first report of preimplantation genetic testing in humans with a pregnancy resulting was published in 1990, while in Greece the procedure takes place for almost a decade now, at specialized clinics. The potential risks concern mainly the status of the embryo after the PGD examination. According, however, to the European statistics (ESHRE), in 97% of the cases, the removal of cells did not harm the foetus and there is no evidence of birth of abnormal children as a result of embryo biopsy.

PGD can also help determine the gender of the embryo (although not specific characteristics such as eye and hair color, IQ, etc.). Nowadays, science allows gender selection, and one can be 99% sure that the results of the embryo biopsy will represent the ultimate genetics of the foetus and subsequent baby.

However, we should state that according to paragraph 26 of Law 3305/2005, gender selection is only allowed for serious medical conditions. Such conditions include couples that one of them has a chromosomal arrangement called a balanced translocation. When the chromosomes in their sperm or eggs join with those of their partner in the fertilized embryo, they have a high percentage of children with chromosomal abnormalities. This is another situation where PGS can help. Although, gender selection for social reasons (e.g. for family balancing) is illegal, it should not be considered unethical. While many have considered stem cells to be the next frontier of modern medicine, reproductive technology may offer hope to many individuals suffering with rare and unique genetic diseases. PGD can, therefore, also be used for “savior siblings”, to create, in other words, a sibling for the purpose of providing biological material (bone marrow, blood, etc.) that can help treat or cure an existing terminally ill child. While there are banks of tissues and cells and records of potential donors, sometimes doctors can’t treat a patient because they can’t find a suitable match.

The people most likely to have an identical tissue type to the patient are their brothers and sisters, hence the term “savior sibling”. Multiple embryos are created and preimplantation genetic diagnosis is used to detect and select the ones that are free of a genetic disorder and that are also a HLA match for an existing sibling who requires a transplant. Upon birth, stem cells are harvested from the child’s umbilical cord to aid the other child. Thee baby is in no way harmed.

• Θα πρέπει να είναι μικρότερη των 50 ετών.
• O σύζυγός της θα πρέπει να είναι σύμφωνος με την παρένθετη μητρότητα.
• Να έχει αποδεδειγμένα προβλήματα υγείας που δεν της επιτρέπουν να μείνει έγκυος και να κυοφορήσει.
• Θα πρέπει να δώσει τα ωάρια της. Αν για κάποιο λόγο υπάρχει πρόβλημα και σ’ αυτό, τότε θα πρέπει να χρησιμοποιηθούν ωάρια δότριας.
• Θα πρέπει μαζί με τον σύζυγό της να καλύψουν όλα τα έξοδα της παρένθετης μητέρας.