Not being able to conceive naturally can have its advantages: how would you like to know in advance if your baby will be free of inheriting genetic disease? While an aspect of assisted human reproduction treatments few consider, it is achievable via pre-implantation genetic diagnosis.
Both legal and ethical, pre-implantation genetic diagnosis does not involve genetic manipulation and closely follows nature’s law of selection as described by Darwin. Healthy embryos are made viable with the best chances of survival, and as such, thousands of children have been conceived under such conditions! Yours could be next.
What is Preimplantation Genetic Diagnosis (PGD)?
Pre-implantation genetic diagnosis – abbreviated to PGD – is a technique which detects serious genetic disease and chromosomal alterations in embryos before they are implanted in the uterus. Biopsies are administered to each embryo between the third and fifth day of fertilisation, and upon receiving results, those free of genetic mutations are chosen for implantation.
As previously outlined, pre-implantation genetic diagnosis is regulated by Spanish legislation and exists within the framework of assisted human reproduction regulations. However, the final decision is always one taken by potential parents as to whether such treatment is practiced on embryos.
Who is Pre-implantation Genetic Diagnosis suited to?
When PGD first appeared in the 1990’s, it was administered in the analysis of X-linked pathologies, although the technique has since been perfected and can detect a wide range of diseases. While it cannot guarantee zero risk, accuracy is very high.
Among the alterations detected via pre-implantation genetic diagnosis are muscular dystrophy, cystic fibrosis, haemophilia, Huntington’s Disease, sickle cell anaemia in addition to Down’s, Patau’s and Edwards’ Syndrome. All of the aforementioned conditions have severe consequences.
In short, it is a test best administered to:
- Couples with a history of implantation failure during IVF treatment.
- Women with recurrent miscarriages, and even more so if chromosomal abnormality is detected.
- Men diagnosed with alterations in the meiosis of spermatozoa.
- Couples in which one or both members are carriers or at risk of transmitting genetic diseases.
- Older women
What are the advantages of Preimplantation Genetic Diagnosis?
Analysing an embyro’s genetic load prior to uterus insertion has a series objective benefits, and amongst the most obvious and interesting advantages are:
- Avoiding implantation of embryos which have no chance of developing due to chromosomal alterations so serious they are incompatible with life and, therefore, lead to failed pregnancies.
- Prolonged in vitro fertilisation treatment. Repertitive implantation can be a frustrating process, and when options are limited, having both a healthy and high-quality embryo can elevate success rates.
- The cost of IVF treatments is lower the fewer attempts are made.
- Reducing any potential uncertainty or doubt is a fundamental advantage as patients can take solace in knowing an embryo will be free of ailments in tandem with a guarantee pregnancy has every chance of being carried to full term.
Pre-implantation Genetic Diagnosis carried out?
Pre-implantation genetic diagnosis is administered by undergoing a trophoblast or blastomere biopsy as both contain the genetic load necessary required for accurate examination. Pre-implantation genetic diagnosis can be executed on the third day of fertilisation, when the embryo has about six or eight cells, or on the fifth day at the blastocyst stage of development.
The extraction of such genetic material does not compromise embryo development and evolution. Different types of chromosome analysis techniques are administered in the laboratory, depending on what is being detected. The most frequent are:
- FISH is used to detect numerical (Down Syndrome) and structural abnormalities
- PCR is administered to expose genetic mutations in DNA which involve monogenic diseases
- CGH arrays, unlike the previous two examinations which are executed on day three, is a biopsy administered on day five which reviews 24 chromosomes. The most accurate test available, it also correlates higher gestation success rates.
- Once analysis is completed, embryos which contain the aforementioned deficiencies are discarded and healthy embryos are frozen or transferred.
Assisted human reproduction treatments are a source of hope for couples who have struggled to conceive, and the peace of mind which comes with testing like pre-implantation genetic diagnosis can guarantee the health of any future children.