Dear Bianca:

I praise God you have asked this question in advance of you doing anything and for wanting to remain loyal to the Church.

I am afraid that you cannot morally do what is being proposed. IVF (In Vitro Fertilization) is a moral evil under all circumstances.  Here is the Catechism on this subject (para 2377 pertains directly to your situation):

2376 Techniques that entail the dissociation of husband and wife, by the intrusion of a person other than the couple (donation of sperm or ovum, surrogate uterus), are gravely immoral. These techniques (heterologous artificial insemination and fertilization) infringe the child's right to be born of a father and mother known to him and bound to each other by marriage. They betray the spouses' "right to become a father and a mother only through each other."

2377 Techniques involving only the married couple (homologous artificial insemination and fertilization) are perhaps less reprehensible, yet remain morally unacceptable. They dissociate the sexual act from the procreative act. The act which brings the child into existence is no longer an act by which two persons give themselves to one another, but one that "entrusts the life and identity of the embryo into the power of doctors and biologists and establishes the domination of technology over the origin and destiny of the human person. Such a relationship of domination is in itself contrary to the dignity and equality that must be common to parents and children." "Under the moral aspect procreation is deprived of its proper perfection when it is not willed as the fruit of the conjugal act, that is to say, of the specific act of the spouses' union . . . . Only respect for the link between the meanings of the conjugal act and respect for the unity of the human being make possible procreation in conformity with the dignity of the person."

In addition to the above, what a lot of people do not know is that IVF involves killing babies. Usually three or more babies must die in order to effect one live birth. This cannot be justified under ANY circumstances.

And in addition to that, to "pre-select" eggs that do not carry the fatal gene is a profound act of distrust in God. Who are you to make such decisions? This is a slippery slope in which people will eventually begin genetic screening and kill any babies that do not contain the right "genes" or genetic engineering in order to get just the right baby one wants (sort of like ordering a hamburger-- "have it your way"). Such a thing has already been proposed. 

The Catechism states:

2378 A child is not something owed to one, but is a gift. The "supreme gift of marriage" is a human person. A child may not be considered a piece of property, an idea to which an alleged "right to a child" would lead....

You need to trust in God. What you are proposing is not only an act of profound distrust in God, but also it robs God of the graces He may wish to give you.

God willing, your child will be healthy. But, if your child is born with this disease, that child is just as much a beautiful gift as a healthy child would be. Who knows what graces God has in store for you through a sick child? Who knows what a gift to the world your sick child may be. You will never know if you play God and "pre-select" your child.

The short answer to your question is that it is grave sin to do IVF. In addition, it is grave sin for the babies who will die in the IVF process.

There is no moral way for you to do this procedure.

But, there is a better way..... trust in God.

God Bless,
Bro. Ignatius Mary