Original ArticlesAnalysis of the CYP2D6 gene polymorphism and enzyme activity in African-Americans in Southern CaliforniaWan, Yu-Jui Yvonnea; Poland, Russell E.c; Han, Guanga; Konishi, Tamikoa; Zheng, Yan-Pingb; Berman, Nancy; Lin, Keh-MingbAuthor Information Departments of aPathology and bPsychiatry, Harbor-UCLA Medical Center, Torrance, CA and cDepartment of Psychiatry,Cedars-Sinai Medical Center, Los Angeles, CA, USA Received 22 December 2000; accepted 18 January 2001 Correspondence to Keh-Ming Lin, Research Center on the Psychobiology of Ethnicity and Department of Psychiatry, Harbor-UCLA Research and Education Institute, Building B-4 South, 1124 West Carson Street, Torrance, CA 90502, USA. Tel: +1 310 222 4266; fax: +1 310 222-4264; e-mail: [email protected] Pharmacogenetics: August 2001 - Volume 11 - Issue 6 - p 489-499 Buy Abstract Despite its importance in drug metabolism and disease susceptibility, CYP2D6 activity and genetic polymorphism have rarely been investigated in African-American populations. In order to bridge this gap, we examined the genotype and phenotype of the enzyme in 154 African-American (AA) and 143 Caucasian (C) normal volunteers. AAs are significantly more likely to possess * 17 and * 5, but less likely to have * 4. Overall, the two groups were similar in their CYP2D6 activity as measured with dextromethorphan as the probe (metabolic ratio 2.21 ± 0.78 for AAs; 2.11 ± 0.86 for Cs; t = 1.02, NS). Two of four AAs and six of seven Cs were classified as poor metabolizers and have two nonfunctioning alleles. CYP2D6 activity is determined by * 17, * 4, * 5 and age in AAs (r2 = 0.33, f = 18.8, P< 0.001) and by * 4 and * XN in Cs (r2 = 0.14, f = 10.8, P< 0.001). These results support previous findings demonstrating the importance of * 17 in determining CYP2D6 activity in AAs. © 2001 Lippincott Williams & Wilkins, Inc.