Single-cell chromosomal imbalances detection by array CGH

Genomic imbalances are a major cause of constitu-tional and acquired disorders. Therefore, aneuploidy screening has become the cornerstone of preimplan-tation, prenatal and postnatal genetic diagnosis, as well as a routine aspect of the diagnostic workup of many acquired disorders. Recently, array comparative genomic hybridization (array CGH) has been intro-duced as a rapid and high-resolution method for the detectionofbothbenignanddisease-causinggenomic copy-number variations. Until now, array CGH has been performed using a significant quantity of DNA derived from a pool of cells. Here, we present an array CGH method that accurately detects chromo-somal imbalances from a single lymphoblast, fibro-blast and blastomere within a single day. Trisomy 13, 18, 21 and monosomy X,as well as normal ploidy levels of all other chromosomes, were accurately determined from single fibroblasts. Moreover, we showed that a segmental deletion as small as 34 Mb could be detected. Finally, we demonstrated the possibility to detect aneuploidies in single blastomeres derived from preimplantation embryos. This technique offers new possibilities for genetic analysis of single cells in general and opens the route towards aneuploidy screening and detection of unbalanced translocations in preimplantation embryos in particular