Notable Histologic Findings in a “Normal” Cohort

Context.— The National Institutes of Health (NIH) Genotype-Tissue Expression (GTEx) project was designed to evaluate how genetic variation and epigenetic effects influence gene expression in normal tissue. Objective.— To ensure that the grossly normal-appearing tissues collected were free from disease, each specimen underwent histologic evaluation. Design.— In total, nearly 30 000 tissue aliquots collected from almost 1000 postmortem donors underwent histologic review by project pathologists, and detailed observations of any abnormalities or lesions present were recorded. Results.— Despite sampling of normal-appearing tissue, in-depth review revealed incidental findings among GTEx samples that included neoplastic, autoimmune, and genetic conditions; the incidence of some of these conditions among GTEx donors differed from those previously reported for other populations. A number of age-related abnormalities observed during histologic review of tissue specimens are also described. Conclusions.— Histologic findings from the GTEx project may serve to improve populational awareness of several conditions and present a unique opportunity for others to explore age- and gender-influenced conditions. Resources from the study, including histologic image and sequencing data, are publicly available for research.