Germ cell nuclear factor (GCNF) is an orphan member of the nuclear receptor gene superfamily. We report the cloning of a cDNA encoding a nem variant of human GCNF from human testis and its expression analysis. Southern blot analysis of the human genomic DNA indicates that the GCNF gene is not closely related to other members within the nuclear receptor superfamily. Chromosomal localization of the GCNF shows that the gene is located on chromosome 9 at the locus q33-34.1. In situ hybridization analysis of GCNF expression in the testis shows that human GCNF is expressed exclusively in germ cells. (C) 1998 Federation of European Biochemical Societies.