Comparison of human adult and fetal expression and identification of 535 housekeeping/maintenance genes

Gene expression levels of about 7,000 genes were measured in 11 different h uman adult and fetal tissues using high-density oligonucleotide arrays to i dentify genes involved in cellular maintenance. The tissues share a set of 535 transcripts that are turned on early in fetal development and stay on t hroughout adulthood. Because our goal was to identify genes that are involv ed in maintaining cellular function in normal individuals, we minimized the effect of individual variation by screening mRNA pooled from many individu als. This information is useful for establishing average expression levels in normal individuals. Additionally, we identified transcripts uniquely exp ressed in each of the 11 tissues.