Preimplantation diagnosis or preimplantation genetic diagnosis is a technique used in in vitro fertilization treatments for selecting embryos to avoid genetic and chromosomal diseases. According to the Spanish legislation, this technique is authorized for the detection of serious hereditary diseases, early appearance and for which there is no cure yet. In these cases, preimplantation diagnosis to select from the fertilized ovules exempt from that disease gene before transferring the embryo to the uterus. The diagnosis is made through the analysis of one of the cells of the embryo to determine whether or not a carrier of the particular gene mutation, or discard it and select for implantation. Thus, it improves the chances of success of IVF treatment and the risk of abortion is reduced.