Résumé
Genomic imprinting mediates the parent-of-origin-specific, mono-allelic expression of many protein-coding genes and noncoding RNAs. This paradigm for epigenetic gene regulation plays diverse roles in mammalian development, growth and behavior. Mechanistically, it involves parentally inherited DNA methylation marks that control clusters of imprinted genes. Perturbation of these epigenetic imprints affects embryonic and postnatal development and leads to complex diseases in humans, including different types of diabetes. This chapter discusses imprinted genes, with emphasis on those that control metabolism and cellular proliferation, several of which encode proteins of the insulin-like growth factor/insulin signaling pathway. Nutrition, chemical pollutants, and other environmental cues can readily perturb DNA methylation imprints, not only during development, but sometimes even in adults. Such epigenetic alterations (“epimutations”) may affect imprinted gene expression and, hence, can have deleterious effects on phenotype. In the future, clinical and environmental imprinting studies will gain from taking a broader approach that considers not only the imprinted gene loci themselves, but also similarly controlled loci located elsewhere in the genome.