One can define genetic engineering as the alteration of the characteristics of an organism through altering its genetic material. It is the process of altering something in the DNA to allow for a change in the organism itself.
Genetic engineering is not a new phenomenon, as it has been in practice for decades. The most prevalent use is in the area of agriculture, providing larger vegetables and fruits and/or enabling plants to better resist diseases and tolerate climate. However, it had never been performed on humans until a Chinese man claimed that he altered the genes of an embryo to make it resistant to HIV, the outcome produced twin girls. It is crucial to note that it is a claim, not a scientific achievement that is published or peer reviewed.
When seeking the Sharias’ positions, some have argued that the following verse can relate to this topic:” I (Satan) will mislead them, and I will create in them false desires. I will order them to slit the ears of the cattle and to deface the fair nature created by God.’ Whosoever forsaking God, takes Satan as a friend, has indeed suffered a loss that is manifest.” 4:119. However, their claim lacks both direct application and clear evidence and can thus be rejected.
In principle, Islam supports both a healthy offspring, as well as, advancing research and seeking treatment for disease. The Prophet said: “Select your spouse carefully in the interest of your offspring because your lineage is a crucial issue.” And when the Messenger of Allah was asked: Should we make use of medical treatment? He replied: "make use of medical treatment, for Allah has not made a disease without appointing a remedy for it, with the exception of one disease, namely old age."
The main challenge of genetic engineering regarding humans as it exists today, is the immaturity of research and the lack of information. Applying the Islamic ruling of “repelling harm takes precedence over procuring benefits” will lead us to be cautious when giving a ruling. If the scientific community can prove to us that no harm will exist, then it is allowed. The scientific community has taught us that the chromosomes work collectively, and while the scientific community can celebrate the success of preventing the embryo from inheriting the HIV virus due to gene manipulation, it is still very unclear of the overall outcome due to the lack of the complete cycle of the human life. If benefit has been proven, then the lawfulness is limited to prevent disease and should be avoided in any other area (i.e: cosmetic, intellectual and physical capabilities, etc.) due to the human dignity.
Please note, due to the Islamic standing on lineage, DNA from outside of the mother and father should be avoided.