title: Preimplantation genetic diagnosis.
abstract: Embryo biopsy for preimplantation genetic diagnosis can be performed on the oocyte/zygote, cleavage stage embryo, or blastocyst, but the majority of centres perform cleavage stage biopsy. Single-cell diagnosis is undertaken by the polymerase chain reaction or fluorescent in-situ hybridization. Technical difficulties have arisen with preimplantation genetic diagnosis, such as allele dropout and chromosomal mosaicism. However, it is hoped that these difficulties can be overcome in the future with the advent of new techniques.
authors.affiliation: University College London Centre for Preimplantation Genetic Diagnosis, Department of Obstetrics and Gynaecology, University College London, UK. joyce.harper@ucl.ac.uk
authors.forename: J C
authors.initials: JC
authors.lastname: Harper
authors.forename: J D
authors.initials: JD
authors.lastname: Delhanty
mesh_terms: D002869:Chromosome Aberrations / Q000175:diagnosis*; D025063:Chromosome Disorders; D004992:Ethics, Medical; D005260:Female; D006801:Humans; D009030:Mosaicism; D011247:Pregnancy; D019836:Preimplantation Diagnosis / Q000379:methods