Systematic comparisons of genomic DNA versus whole-genome-amplified DNA37 reveals increased signal noise. Although this has very little impact on genotype calls, it is problematic for Copy Number Variation detection algorithms such as PennCNV.38 Efforts within the iPSYCH community are making progress towards solving the noise issues. Technical reproductions using RNA microarrays reported in Grauholm et al.35 indicated high reproducibility, independently of spot size, and indicated that the critical factor is storage conditions rather than storage length. Ho et al.39 found differences between cerebral palsy cases and matched controls using dried blood spots from the Michigan neonatal screening. Combined these reports strongly indicate that it is possible to do meaningful transcriptome experiments despite prolonged storage at perceived sub-optimal conditions.
