NGS – Next Generation Sequencing
SANATORIUM Helios, spol. s r.o. offers from January 1, 2018 a new method – New Generation Sequencing (NGS) for the embryo testing (preimplantation genetic screening). This method replaces the so-called microarray (array) comparative hybridization, aCGH.
The sequencing of the new generation allows complete and accurate screening of all 24 chromosomes in the embryo’s genetic equipment. Deviations in the number or structure of chromosomes can most often lead to spontaneous abortion in the early stages of pregnancy or the birth of a child with severe disabilities.
The most well-known syndrome is theDown syndrome caused by chromosome 21, Edwards syndrome (chromosome 18), Patau syndrome (chromosome 13), Turner syndrome (missing one copy of chromosome X), and Klinefelter syndrome (XXY chromosome condition).
Embryos selected by the new generation sequencing have a higher probability of attachment and further correct fetal development in the mother’s uterus.
Women are thus spared of unnecessary embryo transfer and possible subsequent reproductive loss due to the non-standard genetic equipment of the embryo.
NGS is also intended for parents who are carriers of a balanced form of translocation, i.e., the reconstruction of genetic material between chromosomes. The method can offer them an embryo selection that does not translate into an unbalanced form of translocation, a form associated with multiple fetal losses or the birth of an affected offspring.
The latest technology in SANATORIUS Helios, NGS, is more accurate and provides more information about chromosome status of individual embryos. It allows us to get data from thousands of loci (places) on each chromosome. The method works on the principle of parallel sequencing, which is, sequences of thousands to millions of fragments are determined simultaneously.
Compared to the previously used aCGH method, next-generation sequencing has a higher resolution. This fact makes it possible to detect some mosaic embryos that were evaluated as healthy, which in theory could lead to a reduction in implantation success. A higher probability of capturing the change in the structure and the number of chromosome parts (≥10 Mbp) was also described, and thus detected inappropriate embryos in parents with a balanced translocation.
By using the NGS method for PGS, it is therefore possible to increase the success rate of assisted reproduction.