EXPLAINER | Testing embryos for genetic disorder before implantation

The sweeping changes to the Embryo Protection Act in 2018 enabled in-vitro fertilisation to be unshackled from some of the constraints introduced six years earlier.

The changes allowed doctors to be able to fertilise up to five eggs instead of only two, increasing the chances of success. They also made embryo freezing an integral part of the treatment process.

But government was very careful back then to steer clear from introducing pre-implantation genetic diagnosis (PGD) on embryos in those cases where prospective parents carry the risk of transmitting a hereditary disease or genetic disorder to their child.

In parliament, several government MPs at the time made it a point to emphasise that PGD will not be on offer.

However, there was the lone voice of Rosianne Cutajar, who subsequently called for a mature discussion on IVF-linked treatments not offered in Malta such as PGD.

Health Minister Chris Fearne a fortnight ago said government will be drafting changes to the IVF law to make PGD possible. He did not give details and his statements were made in the context of criticism from the Opposition that although the IVF process is free on the national health service, the expensive medication required to stimulate the woman is not.

PGD can help prospective parents who have known genetic disorders or diseases to have a better chance at conceiving healthy babies. But the matter is not without its ethical considerations.

What is PGD?

PGD stands for pre-implantation genetic diagnosis. In a nutshell, it is when genetic tests are carried out on embryos formed through in-vitro fertilisation (IVF) before these are implanted in the womb.

What is the purpose of PGD?

PGD is used to determine whether the embryos are at risk of genetic disease. The test is normally offered when one or both biological parents have, or are carriers of, a known genetic abnormality.

Is this available in Malta?

Not quite. The IVF law does allow doctors to carry out “clinical interventions” on embryos, however these have to be “exclusively diagnostic or therapeutic”. The law also makes it a condition that any such interventions are “in the interests of the health and development of the embryo itself”. So, any diagnostic test could theoretically be carried out, however in practice these are not done because the law imposes other limitations.

What happens if the PGD test flags a genetic abnormality?

In jurisdictions where PGD testing is allowed, the embryo with a genetic abnormality is normally discarded or kept frozen and given up for scientific research. Only healthy embryos are transferred to the womb.

Can embryos be discarded in Malta?

Malta’s law prohibits embryos from being discarded. It also prohibits embryo use for scientific research. If PGD testing is done and a genetic disorder is flagged, the most that can be done is freeze the embryo. However, Maltese law does not allow the woman to undergo a new cycle of IVF until all frozen embryos from a previous cycle are used up. These limitations make PGD useless and impractical.

Which genetic defects are tested for?

In theory, tests can be carried out for all known genetic disorders. However, it depends also on what the legislator allows. In the UK, the Human Fertilisation and Embryology Authority, a regulator, allows testing to take place for over 600 genetic conditions, including Thalassemia, Down’s Syndrome, Huntington Disease, ALS, muscular dystrophy, Fragile X Syndrome, Alzheimer’s Disease and others.

Does PGD alter the embryo genetically?

No. Its purpose is to test embryos for genetic defects.

Who is eligible to undergo PGD?

Malta has no regulations on PGD and the law does not specify who is eligible to undergo a diagnostic test on the embryo. In the UK, PGD can be offered if the woman has ended previous pregnancies because of a serious genetic condition; if the woman already has a child with a serious genetic condition and wants to avoid this happening again; if there is a family history of a serious genetic condition; or if there is a family history of chromosome problems.

What can couples, in Malta, who are at risk of passing on an inherited disorder do to decrease the risk?

As things stand today, they can choose to remain childless, adopt a child or undergo IVF with donated gametes, which became a possibility after the law changed in 2018. They can also opt to conceive naturally and accept the risk of their child inheriting the genetic condition. They can choose to undergo IVF treatment abroad, where PGD is also offered as part of the service.

Another option is to conceive naturally and undergo conventional prenatal diagnosis (PND) following conception. Two such tests are chorionic villus sampling or amniocentesis and are carried out at around 12 and 15 weeks after conception. If the foetus is found to have the genetic condition of concern, the parents have to make difficult decisions about whether or not to terminate the pregnancy or continue with it. However, given that abortion is illegal in Malta, this can only be done abroad.

What are the ethical considerations linked to PGD?

Discarding embryos found to be carrying a genetic disorder can be objectionable to some who believe life starts at conception and no embryo should be thrown away or used for scientific experimentation. However, there is another ethical consideration concerning disabled persons and whether society should strive to eliminate this diversity, even in those cases where babies born with a genetic disorder can still grow up to be functional adults if given the right support.

Others believe PGD can lead to the selection of embryos based on physical characteristics, fearing the creation of eugenic programmes.

What Malta’s current law prohibits

No sex selection

• Sperm cells to be used in artificial fertilisation cannot be selected for the sex chromosome they contain
• However, doctors can select particular sperm cells to prevent the child from falling ill with a sex-linked genetic illness

Improper use of human embryo

• Human embryos have to be created solely for the purpose of implantation in a prospective parent
• Embryos cannot be disposed, handed over or acquired, or removed from a prospective parent before the implantation in the womb is complete

No cloning or research

• Any intervention seeking to create a human being genetically identical to another embryo, foetus, or human being, whether living or dead, is prohibited
• Altering the genetic information of a human germ line cell in an artificial way is illegal
• Any experimentation on human embryos is prohibited
• The formation of chimera and hybrids is also banned