The present invention relates to a purified or isolated polynucleotide encoding human CIDE B protein, the regulatory nucleic acids contained therein, polymorphic markers thereof, and the resulting encoded protein, as well as to methods and kits for detecting this polynucleotide and this protein. The present invention also pertains to a polynucleotide carrying the natural regulatory regions of the CIDE B gene which is useful, for example, to express a heterologous nucleic acid in host cells or host organisms as well as functionally active regulatory polynucleotides derived from said regulatory regions.