PEBP2/CBF is a heterodimeric transcription factor composed of alpha and beta subunits. There are at least three closely related genes, PEBP2alphaA/Cbfa1, AML1/PEBP2alphaB/Cbfa2 and PEBP2alphaC/Cbfa3, encoding the alpha subunit and one beta subunit encoding gene. Structural alterations of AML1 and the beta subunit gene by chromosome translocations are frequently associated with several types of human leukemia. Structural changes of any of these gene products would have potential to affect the function of others. In this study, we isolated the human PEBP2alphaA cDNA by which we mapped the gene to 6p12.3-p21.1. Human chromosome 6p21 is the locus for cleidocranial dysplasia, an autosomal dominant bone disease. Recent gene disruption study revealed that PEBP2alphaA/Cbfa1 plays an essential role in osteogenesis (Komori et al., Cell, 1997, in press). Therefore, a close relationship between human PEBP2alphaA/CBFA1 and this bone disease is strongly implicated.