R. Michael J. Broyde, “Pre-Implantation Genetic Diagnoisis, Stem Cells and Jewish Law” in Tradition 38:1 (Spring 2004), pp. 63-63:
[T]he Jewish tradition would not look askance at the use of genetic engineering to produce individuals when they are created primarily to be of specific assistance to others in need of help. Consider the case of an individual dying of leukemia, in need of a bone transplant, who agree to participate in a cloning experiment with the hopes of producing another like him or who, in suitable time, can be used to donate bone marrow and save the life of a person (and even more so, the donor). The simple fact is that Jewish law and tradition view the donation of bone marrow as a morally commendable activity, and perhaps even morally obliatory such that one could compel it even from a child. Jewish law and ethics see nothing wrong with having children for a multiplicity of motives other than one’s desire to “be fruitful and multiply.” Indeed, the Jewish tradition recognizes that people have children to help take care of them in their old age, and accepts that as a valid motive. There is no reason to assert that one who has a child because this child will save the life of another is doing anything other than two good deeds–having a child and saving the life of another. The same is true for a couple who conceive a child with the hopes that the child will be a bone marrow match for their daughter who is dying of leukemia, and is in need of bone marrow from a relative. While the popular press condems this conduct as improper, the Jewish tradition would be quite resolute in labeling this activity as completely morally appropriate. Having a child is a wonderful, blessed activity; having a child to save the life of another child is an even more blessed activity. Such conduct should be encouraged rather than discouraged. Motives for genetic engineering ought not to be seen as so important.
UPDATE: In response to a question about the status of a clone, here is what R. Broyde wrote earlier in the article (p. 63) about someone who is the result of genetic engineering, which I am assuming is equivalent to a clone:
One could imagine a rabbinic authority, aware of the possibility of ethical lapses in our society, arguing that as a temporary measure based on the exigencies of the times, genetic engineering should not be engaged in until such time as the appropriate educational activity can be embarked on to teach people that genetic engineering is a form of medical treatment and products of genetic engineering are human beings entitled to be treated with full and complete human dignity. (emphasis added)