title: Single cell segmental aneuploidy detection is compromised by S phase.
abstract: BACKGROUND
  Carriers of balanced translocations are at high risk for unbalanced gametes which can result in recurrent miscarriages or birth defects. Preimplantation genetic diagnosis (PGD) is often offered to select balanced embryos. This selection is currently mainly performed by array CGH on blastomeres. Current methodology does not take into account the phase of the cell cycle, despite the variable copy number status of different genomic regions in S phase.
  
  
  RESULTS
  Cell lines derived from 3 patients with different chromosomal imbalances were used to evaluate the accuracy of single cell array CGH. The different cell cycle phases were sorted by flow cytometry and 10 single cells were picked per cell line per cell cycle phase, whole genome amplified and analyzed by BAC arrays, the most commonly used platform for PGD purposes. In contrast to G phase, where the imbalances were efficiently identified, less than half of the probes in the regions of interest indicated the presence of the aberration in 17 S-phase cells, resulting in reduced accuracy.
  
  
  CONCLUSIONS
  The results demonstrate that the accuracy to detect segmental chromosomal imbalances is reduced in S-phase cells, which could be a source of misdiagnosis in PGD. Hence, the cell cycle phase of the analyzed cell is of great importance and should be taken into account during the analysis. This knowledge may guide future technological improvements.
authors: Laboratory for Cytogenetics and Genome Research, Department of Human Genetics, KU Leuven, Leuven 3000, Belgium.
authors: Eftychia
authors: E
authors: Dimitriadou
authors: Laboratory of Reproductive Genomics, Department of Human Genetics, KU Leuven, Leuven 3000, Belgium.
authors: Niels
authors: N
authors: Van der Aa
authors: Laboratory for Cytogenetics and Genome Research, Department of Human Genetics, KU Leuven, Leuven 3000, Belgium.
authors: Jiqiu
authors: J
authors: Cheng
authors: Laboratory of Reproductive Genomics, Department of Human Genetics, KU Leuven, Leuven 3000, Belgium.
authors: Thierry
authors: T
authors: Voet
authors: Laboratory for Cytogenetics and Genome Research, Department of Human Genetics, KU Leuven, Leuven 3000, Belgium.
authors: Joris R
authors: JR
authors: Vermeesch