Original article The genetic variability of MDR1 C3435T polymorphisms in four Southern Chinese populations Qingming Dong a , Bingying Xu b , Yi Tan a , Zheng Liu c , Linwei Tian a , Bao Zhang d , Che-Kit Lin e , Hsiang-fu Kung a , Joseph J.Y. Sung f , Ming-Liang He a, * a Stanley Ho Centre for Emerging Infectious Diseases and Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong, China b Kunming Medical College, Kunming, Yunnan Province, China c Department of Biochemistry, The Chinese University of Hong Kong, Hong Kong, China d Department of Biochemistry, Southern Medical University, Guangzhou, China e Hong Kong Red Cross Blood Transfusion Service, Hong Kong, China f Institute of Digestive Disease, Department of Medicine and Therapeutics and Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong, China Received 21 August 2008; accepted 2 September 2008 Available online 25 September 2008 Abstract Objectives: To investigate the genetic variability of multiple drug resistant 1 (MDR1) gene C3435T polymorphism in four Southern Chinese populations. Methods: Using discrimination real-time PCR, we determined the MDR1 C3435T polymorphism in three ethnic minority groups Lahu (n ¼ 104), Wa (n ¼ 101) and Bulang (n ¼ 100) in Yunnan Province, and Han Chinese (n ¼ 199) in Hong Kong. All of them were residents in Southern China. Results: For 3435 CC genotype, the frequency in Han Chinese in Hong Kong (44.7%) is significantly higher than in Lahu (16.3%) and Wa (29.7%) minorities, P < 0.05. For 3435 CT genotype, the frequency in Han Chinese in Hong Kong (44.2%) is lower than in Lahu (58.7%), P < 0.05. For 3435 TT genotype, frequency in Han Chinese in Hong Kong (11.1%) is lower than in Lahu (25%) and Wa (20.8%), P < 0.05. For 3435 C allele, frequency in Han Chinese in Hong Kong (66.8%) is higher than in Lahu (45.7%) and Wa (54.5%), P < 0.01. For 3435T allele, frequency in Han Chinese in Hong Kong (33.2%) is lower than in Lahu (54.3%) and Wa (45.5%), P < 0.01. For MDR1 3435T allele, the frequencies are significantly higher in our four Southern Chinese populations than in African population (P < 0.001) and significantly lower than in South-west Asians (P < 0.05); Han Chinese in Hong Kong displayed significant difference from all the other ethnic populations except Japanese (P < 0.05); compared with Caucasian and other ethnic Asians, Lahu minority showed no frequency difference (P > 0.05) between Caucasian and other Asians (except Japanese). Conclusions: This is the first study to show the C3435T polymorphism of MDR1 in Southern Chinese populations. The frequency of C3435T, an important determinant for multidrug resistance, displays significant difference in ethnics. It may help for individualizing therapy for cancer, HIV and other common diseases. Ó 2008 Elsevier Masson SAS. All rights reserved. Keywords: Ethnicity; MDR1 gene; P-glycoprotein; Pharmacokinetics; Single nucleotide polymorphism (SNP) * Corresponding author. Stanley Ho Centre for Emerging Infectious Diseases, and Li Ka Shing Institute of Health Sciences, School of Public Health, Prince of Wales Hospital, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong. Tel.: þ852 3763 6096; fax: þ852 2145 8013. E-mail address: mlhe@cuhk.edu.hk (M.-L. He). 0753-3322/$ - see front matter Ó 2008 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.biopha.2008.09.003 Available online at www.sciencedirect.com Biomedicine & Pharmacotherapy 63 (2009) 658e662