The role of ethnicity in cancer susceptibility gene polymorphisms: the example of CYP1A1

Individual susceptibility to cancer from environmental agents may beinfluenced by polymorphic metabolic genes such as CYP1A1. The CYP1A1 genecontains four major polymorphisms identified to date. A modern nomenclaturesystem, used with other genes, is presented to clarify the identity ofthese polymorphisms. The various CYP1A1 alleles exhibit populationfrequencies that depend on ethnicity. The association of these alleles withcancer at several sites has also been found to depend on racial or ethnicorigin of the study population. Statistical considerations, such as theneed for large studies when the power to detect a rare polymorphism is low,and ethnic differences in genetic linkage disequilibrium are among possiblereasons for ethnic-specific effects on cancer susceptibility related tometabolic gene polymorphisms. New efforts to determine populationfrequencies of such polymorphisms are essential for future research in thisarea.