What is the Islamic view on preimplantation genetic diagnosis during invetro fertilisation? Can we destroy embryos carrying genes for diseases and thus avoid transfer of such embryos to the uterus of the patient?

Praise be to Allah, the Lord of the Worlds; and blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
Islam has urged people to study and has ordered them to use their minds and think of ways to improve their wellbeing. Allah Says (interpretation of meaning): "Are those who know equal to those who know not?" It is only men of understanding who will remember (i.e. get a lesson from Allâh's Signs and Verses).}[39:9]. He also Says: {They know only the outside appearance of the life of the world}[30:7]. Allah also Says: {Do not you then understand?} {will you not then take thought?}.
There is no contradiction or conflict between the Islamic religion and the good science, which benefits humanity.
In fact any knowledge - Sharia sciences or experimental sciences - that is needed by the Muslim community in its spiritual or material life is a common obligation on the Muslim Ummah as a whole. So it is an obligation on the Muslim Ummah that some of its sons master such sciences otherwise everyone in the Ummah commits a sin because the Ummah becomes dependent upon others. This, in turn, might weaken the Ummah causing its humiliation. Allah has made clear that the Cosmos is a vast place for meditation, research, and evidence of the greatness of The Creator, Allah The Almighty. Allah Says (interpretation of meaning): { And on the earth are signs for those who have Faith with certainty,} [51:19, 20]. He also says: {We will show them Our Signs in the universe, and in their ownselves, until it becomes manifest to them that this (the Qur'ân) is the truth.} [41: 53]. He says: {(Allâh says to His Prophet Muhammad SAW): "Allâh (Alone) created the heavens and the earth with truth (and none shared Him in their creation)." Verily! Therein is surely a sign for those who believe.} [29: 44].
So, the discoveries that are common these days are all proofs of the greatness of the Creator. The person who sees these things should bear witness that there is no God but Allah and believe in His oneness and abide by His orders. All sciences and inventions should be surrounded by a fence of morals. They should also be tightly linked with the religions ethics and the true belief. Every science should be tightly linked with the Sharia as the latter is the scales by which everything is weighed, otherwise both the science and the scientist will be source of bad for the person.
One of these discoveries is the Genome, which is the genetic map of the human being. We shall discuss here the first step of this discovery. The thought about setting a genetic map for all people in America started in 1988 in February. The federal council of research along with the federal academy of science constituted a committee to make up this map. And the project started in October 1990. At first it was an American project which was supposed to last for fifteen years.
Since the project was so huge and so ambitions more countries joined it and several billion dollars were assigned for it. The first and most important part of the project is finished and the second part will end in 2003 two years before its initial deadline. This project is meant - according to those responsible of it - to be a real beginning of a "full knowledge" of all that affects the health of the human being the development, the evolution, the diagnosis in the future, as well as the treatment at the level of the genetic agent and the knowledge of the different genes that cause illnesses and diseases.
This project has its advantages but also its disadvantages. It can help diagnosis cancer in its early stage as well as the genetic illnesses, which reach 500 illnesses. But its disadvantages are numerous and extremely dangerous on both the social and moralistic levels.
The knowledge of the genetic map of the person could be used for instance as a justification to make a criminal innocent for the reason that he carries a gene that is responsible for his anomalous behaviour. It could also cause disastrous psychological consequences for a person if he knows for example, that he carries a gene responsible for a very grave disease such as cancer; or he might lose motivation and ambition if he knows he lacks genes for intelligence. This science could be used to subjugate people by inventing serums or vaccines against the genes for courage, turning these people into a "herd of domesticated animals". Its effect would then be more disastrous than the use of atomic weapons. But, as we mentioned before, every science has to be surrounded by a "fence" of the right religion and morals so that people will benefit from it without being adversely affected by it.
So any science that is devoid of religious and moral guidance is turned against people and has negative effects upon them. On the other hand, the fact that these genes are the mechanisms for certain illnesses or the capacity for certain action or behaviour is known only to Allah because even if we know the function of these genes other factors in the life of the person give him the right of choice for his action and behaviour.
The Prophet said: "Every newborn is born with a natural predisposition". This is a hint from the Prophet about the environment and its influence on the person's behaviour. If, for instance, there is an environment conducive for a particular illness and there is a predisposition for it, it is likely to occur.
All this results in yet another kind of fatalism imposed by western society and propaganda for spreading crimes and anarchy.
As for abortion of fetuses that carry defective genes, this is forbidden even in the first 120 days, i.e. before life is infused in the fetus, because this is not a sound reason as this illness will not develop except with the existence of other factors.
But if there is a medical report from authentic and specialized doctors proving that this fetus carries a very dangerous disease that could not be cured, and that it will be a source of unhappiness for its parents if it survives and if this is done before the end of the first 120 days and if its parents apply for its abortion, then there is no harm in doing so.
But, if 120 days have passed from the beginning of pregnancy, it becomes forbidden to make abortion because this is synonymous to killing a person without any right to do so. If it is proved without any doubt that not aborting this fetus will endanger the life of his mother, then it is lawful to cause it to be aborted whether it is carrying a dangerous disease or not.

Allah knows best.