Plant & Animal Genome IX Conference

Workshop: Cattle/Sheep
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GENOMIC IMPRINTING AND ITS RELEVANCE TO LIVESTOCK

Duke University, 139 Env. Safety Building, 131 Research Drive, Durham, NC, 27710, USA

The evolution of genomic imprinting in mammals occurred over 100 million years ago, and resulted in the formation of genes that are functionally haploid because of parent-of-origin dependent expression. The role of imprinted genes and related phenotypes in livestock is becoming increasingly evident. Despite ample evidence suggesting the presence of imprinted genes on human chr. 14 and the orthologous regions in mice (chr. 12) and sheep (chr. 18), their identity has remained elusive. Herein, we report the identification of two reciprocally imprinted genes, DLK1 and GTL2, which together define a novel imprinting cluster on human chromosome 14q32. DLK1 (delta, Drosophila, homolog-like 1) is a paternally expressed gene that encodes for a transmembrane protein containing six epidermal growth factor (EGF) repeat motifs closely related to those present in the delta/notch/serrate family of signaling molecules. The maternally expressed GTL2 (gene trap locus 2) gene encodes for a non-translated RNA. In sheep, paternal transmission of mutations in the callipyge (CLPG) gene, mapped to ovine chr. 18, result in improved feed efficiency, animal leanness, and muscular hypertrophy. The paternal expression, chromosomal localization, and biological function of DLK1 make it a likely candidate gene for the callipyge phenotype in sheep.