facility using the Illumina Oligoset (HEEBO7) of 49,152 70-mer probes were used. After purification, the labelled aRNAs are hybridized overnight to the oligo arrays in 53 SSC, 25% formamide and 0.2% SDS buffer at 45 °C using Maui Mixer FL hybridization chambers (BioMicro Systems). The slides are then washed at room temperature in a series of SSC/SDS buffers and dried by centrifugation. A laser confocal scanner (Agilent Technologies) was used to scan the hybridized microarrays. DeArray software (Scanalytics, Inc.) was used to export intensity data. Probes that were non-human, nonspecific (that is, mapped to >1 expressed sequence), incorrectly annotated, or probes containing polymorphisms with minor allele frequency > 0.01 according to HapMap in either YRI or CEU populations were removed from the analysis. Intensities below an empirically determined low intensity cutoff of 5.3 on the log2 scale were dropped from the data. Probes with fewer than half of the fetal or postnatal data pointsremaining after thisstep were removed. Additionally, outliers defined as >6 mean average deviations from the age-appropriate linear fit were removed. The total number of probes remaining was 30,176. After background correction on the linear scale, log2 ratios (sample/reference) were normalized across mean log2 florescent intensities using loess
