24-chromosome copy number analysis: a comparison of available technologies

Chromosome aneuploidy, an abnormal number of chromosomes, in human gametes and embryos is a major cause of IVF failure and miscarriage and can result in affected live births. To avoid these outcomes and improve implantation and live birth rates, preimplantation genetic screening aims to identify euploid embryos before transfer but has been restricted to analysis of a limited number of chromosomes. Over the past 15 years, various technologies have been developed that allow copy number analysis of all 23 pairs of chromosomes, 22 autosomes, and the sex chromosomes, or “24-chromosome” copy number analysis in single or small numbers of cells. Herein the pros and cons of these technologies are reviewed and evaluated for their potential as screening or diagnostic tests when used in combination with oocyte or embryo biopsy at different stages.