FISH and PCR Techniques
To perform molecular cytogenetic analysis the cells obtained from the embryo biopsies are marked with various florescent dyes in preparation for analysis. This method is called FISH (Fluorescent in Situ Hybridization). Different parts of the chromosome can be dyed based on the purpose of the test. The advantage of the FISH method is that the dye can be applied directly to the cell’s nucleus without having to isolate the specific chromosomes. For Preimplantation Genetic Diagnosis, a panel of as many as 9 chromosomes (13, 16, 18, 21, 22, 15, 17, X and Y) can be dyed for analysis.
The blastomeres which are removed from the embryo for biopsy are placed in tubes where the DNA is denatured and multiple copies of a gene are generated.