A cytochrome P‐450 gene family mapped to human chromosome 19

We have recently isolated a cloned cDNA coding for a cytochrome P‐450 of human liver microsomal membranes, which corresponds to a major phenobarbital‐inducible cytochrome P‐450 of rat liver. This human cytochrome P‐450 is encoded by a member of a multigene family. DNA extracted from a panel of 12 independent human‐rodent somatic cell hybrids was analysed by Southern blot hybridization with the cloned cDNA. The results indicate that all components of this cytochrome P‐450 gene family are located on chromosome 19. Evidence from hybrids derived from an individual carrying a balanced translocation suggests a regional localization of 19p13.2→qter. Analysis of human metaphase chromosomes by in situ hybridization localizes this cytochrome P‐450 gene family further to the long arm of chromosome 19 in the region q13.1→qter. We propose the designation P450PB for this locus.