Genetic aspects of metabolic processing of chemical substances.

The Ah locus in the mouse controls the induction of cytochrome P1-450 and at least 10 associated monooxygenase activities. These enzyme systems metabolically potentiate and detoxify chemical carcinogens, environmental pollutants, drugs, and other chemicals, as well as numerous endogenous substrates. With certain substrates cytochrome P1-450 is known to produce a predominance of reactive intermediates and products that differ from those formed by other cytochrome P-450 species. Numerous conditions in the mouse, including cancer, drug toxicity, and birth defects, are directly associated with the Ah locus, which is considered to be a single gene or a small number of genes.