1♂︎—Sperm is collected from a male. 1♀︎—Eggs are collected via in vitro fertilization from a female. 2a—The sperm and eggs are fertilized. 2b—The resulting embryos are kept safe and watched to see which will thrive. 3a—The embryos are allowed to develop; those that thrive are given identifiers. 3b—A genetic test is run on each embryo for a given trait and the results are matched with the embryos. 4—The embryos without the desired trait are identified and discarded. 5—The remaining embryos are allowed to grow to the point that they can be implanted. 6a—The embryos with the desired trait are implanted. 6b—The embryos result in a healthy pregnancy. 6c—Fraternal twins with the desired trait, not expressed in their mother, are born.<unk>  <unk>  or PIGD) is the genetic profiling of embryos prior to implantation (as a form of embryo profiling), and sometimes even of oocytes prior to fertilization.<unk>  is considered in a similar fashion to prenatal<unk> . When used to screen for a specific genetic disease, its main advantage is that it avoids selective abortion, as the method makes it highly likely that the baby will be free of the disease under consideration.<unk>  thus is an adjunct to assisted reproductive technology, and requires in vitro fertilization (IVF) to obtain oocytes or embryos for evaluation. Embryos are generally obtained through blastomere or blastocyst biopsy. The latter technique has proved to be less deleterious for the embryo, therefore it is advisable to perform the biopsy around day 5 or 6 of development. The world's first<unk>  was performed by Handyside, Kontogianni and Winston at the Hammersmith Hospital in London. Female embryos were selectively transferred in five couples at risk of X-linked disease, resulting in two twins and one singleton pregnancy. The term<unk>  genetic screening (PGS) refers to the set of techniques for testing whether embryos (obtained through IVF/ICSI) have abnormal chromosomes' number. In other words, it tests if an embryo is aneuploid or not. PGS is also called aneuploidy screening. PGS was renamed<unk>  for aneuploidy <unk> -A) by<unk>  International Society <unk> IS) in 2016. The<unk>  allows studying the DNA of eggs or embryos to select those that carry certain mutations for genetic diseases. It is useful when there are previous chromosomal or genetic disorders in the family and within the context of in vitro fertilization programs. The procedures may also be called<unk>  genetic profiling to adapt to the fact that they are sometimes used on oocytes or embryos prior to implantation for other reasons than<unk>  or screening. Procedures performed on sex cells before fertilization may instead be referred to as methods of oocyte selection or sperm selection, although the methods and aims partly overlap with<unk> .
Preimplantation genetic diagnosis
Preimplantation genetic haplotyping
Non invasive prenatal testing
Pre-conception counseling
Genetic diagnosis of intersex
Prenatal testing
Magnetogenetics
Fetal echocardiography