With regard to germ line cell therapy, “the risks connected to any genetic manipulation are considerable and as yet not fully controllable” and therefore “in the present state of research, it is not morally permissible to act in a way that may cause possible harm to the resulting progeny
This is very interesting. It would appear that the Church does not view gene therapy as inherently immoral.
Is this a new position for the Church?
The Church always supported anything that is strictly therapeutic.
The complete document goes into more detail on the different types of gene therapy, emphasizing caution in any use of genetic treatment.
In a nutshell, the Church is for life. Therapies that do not destroy life and can make a life better are not immoral.