Gene therapy works in animals but has had limited success in human patients. It may also have unforeseen consequences and has included some human deaths in research studies that have used human patients.

However, there have been cases where human patients have been successfully treated using gene therapy techniques.

Examples of controversial biological procedures are gene therapy and genetic engineering.

Gene therapy

Some people have diseases caused by faulty genes. The aim of gene therapy is to replace the faulty genes with normal fully functioning genes.