Cell transfer and Whole Genome Amplification (WGA)
Biopsied cells are washed and transferred into a reaction tube.
Their DNA is extracted, then enzymes are used to duplicate (amplify) the 3-6 copies of the genome into about a million copies.
A mixture of normal DNAs is amplified at the same time in a separate reaction to provide a reference.
CGH Analysis (Labelling and Hybridisation)
To distinguish between the embryo and reference DNAs, a different coloured fluorescent dye is linked to each:
- A red dye can be attached to the control DNA.
- A green dye can be attached to the embryo DNA
The sample and reference DNAs are mixed and applied to a microarray slide.
Image provided courtesy of Agilent Technologies
CGH Analysis (Microarray)
The microarray contains thousands of unique DNA segments from across all chromosomes.
The sample and reference DNA ‘stick’ to the matching DNA spots on the microarray.
A scanner reads the colour at each spot to compare the amount of embryo and reference DNAs.
||Equal red and green = normal 2 copies of the chromosome.
|| Green means more embryo DNA = trisomy (3 copies).
|| Red means less embryo DNA = monosomy (1 copy).
The chromosomes results are interpreted and reported to the doctor.