What is the difference between WG6, Ref8, and HT12 Illumina beadchips?
All of these Illumina beadchips are genome-wide expression arrays. The key difference is the depth of coverage per sample. On the WG6 chips there are ~48,000 transcripts per sample, whereas there are only ~24,000 per sample on the Ref8. The Human-HT12 arrays also contain ~48,000 transcripts per sample, but the representation of each of these transcripts on the array is half as much as that of the WG6 arrays. Therefore there is a diminished range of intensity between high and low expressed probes, but equal genomic coverage between the HT12 and WG6 arrays. Due to the variations in probe density per sample on the arrays, Illumina is able to fit 8 sample spaces on each Ref8 chip, 12 samples on every HT12 chip but only 6 on each WG6 chip. For more details on these chips, please consult the Illumina website.
