Publisher Summary The α subunit of the heterotrimeric G protein Gs (Gsα) is critical for receptor stimulated intracellular cAMP generation. The human and mouse Gsα genes (GNAS1 and Gnas, respectively) are located within syntenic regions at 20q13 in human and distal chromosome 2 in mouse. The GNAS1/Gnas genes are imprinted based on three criteria: mutations or UPDs that specifically disrupt the maternal or paternal allele lead to distinct phenotypes; several gene transcripts are expressed primarily or exclusively from only one parental allele; and regions of the gene are methylated in only one parental allele. Further studies will need to confirm whether or not Gsα is imprinted in specific tissues, such as the renal proximal tubules, in humans and, if so, what is the mechanism by which tissue-specific imprinting occurs. It will also be of interest to determine the mechanisms by which the gene has multiple oppositely imprinted transcripts, specifically whether the imprinting of each transcript is established independently or whether one specific region is critical for establishing imprinting throughout the GNAS1 locus.