Genomic DNA is extracted from white blood cells and specific fragments, typically less than 100 nucleotides, are captured and read using short-read sequencing.

“in the white blood cells in that tube of blood they open those up to extract what we call the genomic DNA so the DNA included in each of the nuclei of those white blood cells from that they uh depending on how they did this they uh may have captured out specific fragments and then read through all of that using what we call short read sequencing again my guess in terms of this that short read sequencing was probably less than 100 nucleotides for each little fragment”