STA was performed on a GeneAmp PCR 9700 system (Applied Biosystems, Foster City, CA) in a 5 ml reaction containing 1 Â TaqMan PreAmp master mix (Applied Biosystems, Foster City, CA), 225 nM of primers for both RNase P and the target gene and 10-50 ng DNA. Thermocycling conditions were 958C, 10 min hot start and five cycles of 958C for 15 s and 608C for 2 min. The products were diluted prior to the copy number analysis on the digital array based on their initial concentrations so that there would be about 500-600 RNase P molecules per panel.