Determine of embryo’s sex by PGD method

Preimplantation genetic diagnostics (PGD) allows leading the genetic test of embryo before embryo transfer to uterus. This examination takes a place during the IVF program and allows transferring only normal embryos to uterus. This examination takes a place on the third day of embryo’s development. Genetics is a field of medicine that solves the problem of genetic and family diseases. On the base of facts genetics gives the recommendations according to next reproduction of the family. Simultaneously, with the help of laboratory examinations, genetics looks for the way to predict the birth of children with chromosomal or gene anomalies.

The main part of human genetic material is concentrated in the cell nuclei. There are 23 pares of chromosome in the normal human nuclei. There are two chromosomes in the nuclei, which determine the sex of human organism (XY – for males, XX – for females). The normal male karyotype is 46, XY. The normal female karyotype is 46, XX. Every normal sex cell has 23 chromosomes. Oocyte has only X as a sexual chromosome. Spermatozoa may carry X or Y as a sexual chromosome.

If there is something wrong with sexual cells development the embryo, which appears as a result of fertilization from these cells, may carry serious pathologies. Such pathologies can be found out with the help of ultrasonic investigation, biochemical and genetic tests. But new methods appear. Preimplantation genetic diagnostics (PGD) is one of the new methods. This method (with the IVF method) gives the families with genetic diseases a new opportunity to have a healthy baby.

Chromosomal diseases are divided into two groups:

• pathologies, the reason of which are structure chromosomes anomalies;
• anomalies of the number of chromosomes (aneuploidies). Process of embryo examination on the fact of common anomalies in the number of chromosomes is call preimplantation genetic screening (PGS).

The PGD is necessary in next cases:

1) Women’s age is more then 35 years;
2) There are several IVF program without any result in the past;
3) There are some pathologies in the karyotype of one member of the couple;
4) There is some family disease.

It is very important to receive necessary quantity of embryos to lead PGD. The examination may be carry out for embryos on the third day of their development. On the third day of development embryos have 6-8 cells, which are called blastomeres. The embryologist receive one blastomere from the embryo with the help of special micromanipulator. After genetic examination normal embryos are transferred to uterus.

Preimplantation genetic diagnostic (PGD) by FISH method.

Unfortunately PGD (as a PGS) cannot guarantee getting of pregnancy. Even without additional manipulations with embryos one receives the pregnancy in the 40-45 % of cases. The procedure of PGD sometimes even can decrease the opportunity to receive the pregnancy. After the embryo implantation there is an opportunity of prenatal genetic diagnostics. The chorionic cells and amniotic cells are used for examination. But all these procedures may influence on the pregnancy (risk of abort). The truthful of PGS by FISH method is 95 %. To receive the blastomere from the embryo we use laser hatching. The DNA-probes of Vysis company (USA) are used for diagnostics. There is an opportunity to check X, Y, 13th, 18th and 21st chromosomes.