For some couples, the birth of a child with a malformation or a serious disease is the first indication that one or both parents are carriers of a genetic mutation that becomes a genetic disorder in the children, Some couples have already had tests for the most frequent genetic mutations like cystic fibrosis and know the risks they have to have a child with serious medical problems.

In the past, once the parents were informed about the genetic disease, the only thing that could be discussed was the probability that their future children could have the disease. With prenatal diagnosis by corial biopsy or amniocentesis and the development of the possibility of directly examining the fetus’ genes, the couple is informed how the fetus is. If the fetus has a disease, the couple has to make the difficult decision whether or not to terminate the pregnancy.

The human genoma project has helped to clarify the exact molecular basis of many hereditary diseases. The development of assisted reproduction, IVF with embryo micromanipulation techniques and PCR has helped us find a technique that allows us to genetically diagnose embryos before replacing them into the uterus. This process is called Preimplantation Genetic Diagnosis.