title: A 24-chromosome FISH technique in preimplantation genetic diagnosis: validation of the method.
abstract: Embryo screening for aneuploidy (AS) is part of preimplantation genetic diagnostics (PGD) and is aimed at improving the efficiency of assisted reproduction. Currently, several technologies, including the well-established fluorescence in situ hybridization (FISH) technique, cover the screening of all chromosomes in a single cell. This study evaluates a novel 24-chromosome FISH technique protocol (FISH-24). A total of 337 embryos were analyzed using the traditional 9-chromosome FISH technique (FISH-9) while 251 embryos were evaluated using the new FISH-24 technique. Embryos deemed nontransferable on Day 3 were cultured in vitro to Day 5 of development, then fixed and reanalyzed according to the technique allocated to each treatment cycle (107 embryos analyzed by FISH-9 and 111 by FISH-24). The global error rate (discrepancy between Day 3 and Day 5 results for a single embryo) was 2.8% after FISH-9 and 3.6% after FISH-24, with a p value of 0.95. Thus, we have established and validated a 24-chromosome FISH-based single cell aneuploidy screening technique, showing that the error rate obtained for FISH-24 is independent of the number of chromosomes analyzed and equivalent to the error rate observed for FISH-9, as a useful tool for chromosome segregation studies and clinical use.
authors.affiliation: Center for Embryo Medicine and.
authors.forename: Silvia F
authors.initials: SF
authors.lastname: Fernández
authors.forename: Estefanía
authors.initials: E
authors.lastname: Toro
authors.forename: Ana
authors.initials: A
authors.lastname: Colomar
authors.forename: Marisa
authors.initials: M
authors.lastname: López-Teijón
authors.forename: Esther
authors.initials: E
authors.lastname: Velilla
mesh_terms: D002877:Chromosomes, Human; D006801:Humans; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D019836:Preimplantation Diagnosis
keywords: 24-chromosome analysis; FISH; aneuploidy screening (AS); error rate; preimplantation genetic diagnosis (PGD)