CGH (Comparative Genomic Hybridization)

CGH is a method of simultaneous examination of all chromosomes to determine their quantitative and qualitative abnormalities. This method makes it possible to exclude the development of Down syndrome and other chromosomal pathologies in the unborn child, which are accompanied by physical malformations and severe mental retardation. Modern technologies allow the specialists to choose the most promising embryo(s) with a normal set of chromosomes, which will significantly increase the chances of a positive program result and the birth of a healthy child.

CGH is the most advanced technology for examining the entire genome of the embryo, in comparison with the method of fluorescence in-situ hybridization (FISH), the big disadvantage of which is the limitation in the number of chromosomes studied.

A comparative hybridization analysis is carried out within the framework of IVF programs on the 5th day of embryo cultivation, when it reaches the blastocyst stage. With the help of microinstruments, the embryologist picks up several cells of the surface layer of the fetal membrane. After that, the embryos are frozen for the duration of the analysis.

Samples are sent to the genetic laboratory where the CGH test is performed. This method is based on a comparison of the test and control (normal) genomic samples. Based on the results of the analysis, a genetically healthy embryo(s) is selected, defrosted and, after a woman’s premedication, transferred to the patient’s uterus.

Embryo diagnostics using the CGH method refers to the analysis of the entire genome and detection of chromosomal abnormalities. Other PGD methods are used to detect mosaicism, local gene mutations, and monogenic diseases.