We have isolated the human homolog of a novel rodent gene that may be involved in the regulation of pituitary gene transcription. The human PREB gene encodes a predicted protein of 417 amino acids, exhibiting several sequences characteristic of the WD-motif protein family. PREB transcripts were detected in every human fetal and adult tissue examined, although a great variation in levels of expression was observed. PREB was mapped to human Chromosome 2p23, a region of the genome associated with partial trisomy 2p syndrome. Although variable, the common duplication phenotype includes facial abnormalities, skeletal defects, growth and mental retardation, congenital heart and neural tube defects, and abnormalities of the genitalia. We propose that PREB has a role during human development and that abnormal dosage of this transcription factor may be involved in some of the developmental abnormalities observed in patients with partial trisomy 2p.