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 diagnosis (PGD) is one of the new methods.
Preimplantation Genetic Diagnosis (PGD) is a procedure aimed to increase the chances for successful pregnancy and delivery of a healthy child by detecting chromosome abnormalities or single-gene disorders. Preimplantation (pre-implantation) genetic diagnosis (Preimplantation Genetic Diagnostics – PGD) allows the analysis of a human embryo for the presence of the most common aneuploidia (chromosomal abnormalities) before implantation of the embryo in the uterus (after IVF and ICSI).