Received for publication October 26, 2006.
Revised January 25, 2007.
Accepted for publication January 25, 2007.

A novel duplication type of CYP2A6 gene in African-American population

Abstract

Human CYP2A6 is responsible for the metabolism of nicotine and the its genetic polymorphisms affect smoking behavior and risk of lung cancer. In the present study, we identified a novel type of CYP2A6 gene duplication that is created through an unequal crossover event with the CYP2A7 gene at 5.2 - 5.6 kb downstream from the stop codon. The novel duplication type of CYP2A6 was found in African-Americans (n = 176) at an allele frequency of 1.7%, but not found in European-American (n = 187), Korean (n = 209), or Japanese (n = 184) populations. The plasma cotinine/nicotine ratio in subjects having the novel CYP2A6 gene duplication with the CYP2A6*1 allele (10.8 ± 7.0, n = 4) was 1.4 fold higher than that in homozygotes of the wild type (8.0 ± 5.0, n = 87), although the difference was not statistically significant. The findings in the present study suggested that the novel duplicated CYP2A6 allele, which is specific for African-Americans, would increase nicotine metabolism and may affect the smoking behavior.

Key words: CYP2A, cytochrome P450, genetic polymorphism

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