Couples wishing to balance their family, resort to many different methods, some of which are not scientific and have proven no evidence such as the Chinese calendar, diet or arranging when and what time to have sexual intercourse. Microsort is also a technique that is said to improve the chances that the embryos developed will be of the desired gender after PGD testing.
The Microsort method separates sperm according to their X and Y chromosome. In other words, the sperm taken from the male is prepared in the laboratory and the sperm sorting is carried out. At the end of the process, the desired X and Y chromosomes are separated. These sperm samples can be used for inoculation or in vitro fertilization according to the desired sex. The success of X chromosome separation is 70-75% while achieving 80-85% success in X chromosome separation.
The only way to determine gender is to carry out genetic testing on embryos, as this is a more reliable method and carries a 99.9% chance of accuracy. This tests carried out are Pre Implantation Genetic Diagnostic with FISH, array CGH or NGS techniques.
IVF treatment needs to be carried out first before a genetic biopsy can be carried out. The IVF tests are carried out and when protocol is determined, the stimulation is begun. Once embryo development takes place, depending on the type of genetic testing a biopsy is carried out, when one or more cells are taken away from the embryo. This cell(s) will determine the chromosomes within the embryo and can identify the sex. The various genetic testing methods will influence on what day the biopsy is carried out and whether a transfer can be carried out within the same cycle.
Fluorescent in situ hybridization (FISH):
FISH is an older technique and is applied to the cell nuclei and one cell is taken away from the embryo and then a certain number of Chromosomes can be screened. If necessary then two cells can be biopsied for the FISH process and the biopsy is carried on day 3 of embryo development. The chromosomes usually detected with the FISH test are 13, 18, 21, X and Y so a total of 5 chromosomes but the number of chromosomes screened can be increase from 5 to 7 or 9 chromosomes. When the biopsy is carried out the results of the genetic testing are back after 48 hours, this means that if there is a viable embryo found then a transfer can take place on day 5 of embryo development (Blastocyst).
CGH is a new cytogenetic technology that evaluates areas of the human genome for gains or losses of chromosome segments at a higher resolution. The main advantage of array CGH is the ability to explore all 46 chromosomes in a single test and to detect any DNA imbalance. The IVF procedure is carried out but the embryo biopsy is carried out on day unlike the FISH technique. At the blastocyst stage (5th day of development) a trophectoderm biopsy is carried out, this enables 3-4 cells to be taken from the embryo and a more detailed chromosome analysis can be carried out. At day 5 the embryo is nearly 100 cells so the biopsy carried out has low chances of damage to the embryo. Array CGH, screens the entire chromosomal structure of the embryo is; that is, all 24 chromosomes are evaluated to determine whether there is a numerical or structural defect in the chromosomes. Since the embryo is biopsied during the blast phase and the embryos are usually frozen individually after embryo biopsy. If there is a suitable healthy embryo for a transfer then this will be transferred in a later cycle as the results can take up to 2 weeks to be released from the genetics lab, this form of testing is more reliable and we would recommend one embryo for a transfer.
Next Generation Sequencing Method:
The treatment and biopsy technique and timing for NGS is the same as array CGH. Basically, all chromosomes are evaluated with NGS. There is no difference between the two methods except for the technical details in the genetic review. In cases where NGS is used, and embryos are frozen individually after embryo biopsy. If a suitable healthy embryo is found after the results, the transfer again will be carried out in a later cycle.