Abstract: The present invention relates to mammalian mahogany genes, including the human mahogany gene, which are novel genes involved in the control of mammalian body weight. The invention encompasses nucleotide sequences of the mahogany gene, host cell expression systems of the mahogany gene, and hosts which have been transformed by these expression systems, including transgenic animals. The invention also encompasses novel mahogany gene products, including mahogany proteins, polypeptides and peptides containing amino acid sequences mahogany proteins, fusion proteins of mahogany proteins polypeptides and peptides, and antibodies directed against such mahogany gene products. The present invention also relates to methods and compositions for the diagnosis and treatment of mammalian body weight disorders, including obesity, cachexia, and anorexia, and for the identification of subjects susceptible to such disorders.