Frequency of C3435T single nucleotide MDR1 genetic polymorphism in an Asian population: phenotypic–genotypic correlates

Abstract

Aims To investigate the frequency of the single nucleotide polymorphism C3435T in exon 26 of the MDR1 gene in Asians and to determine the functional significance of this SNP with the clinical pharmacokinetics of oral cyclosporin (Neoral) in 10 stable heart transplant patients. Methods The MDR1 C3435T polymorphism was investigated in 290 healthy Asian subjects (98 Chinese, 99 Malays and 93 Indians). We also compared the MDR1 polymorphism between the Asian population studied here and the published data on Africans and Caucasians. The clinical relevance of this SNP on oral bioavailability of a known P-gp substrate, cyclosporin, was assessed in 10 stable Chinese heart transplant patients. Results The homozygous TT genotype was observed in 32%, 28% and 43% of Chinese, Malays and Indians. The homozygous CC genotype was found in 25% of Chinese and Malays compared with 18% of Indians. The Indians had a lower frequency of the C allele In this Asian population, the overall distribution of genotypes (CC, CT and TT) and allele frequencies were significantly different from those in Africans ( P < 0.001). The results were also significant when the Chinese, Malays and Indians were compared separately with the African group ( P < 0.001). Compared with the Caucasian data, the overall distribution of genotype and allele frequencies in the Asian population were also significantly different ( P £ 0.05). However, when each Asian ethnic group was compared separately with the Caucasians, only the Indians were found to be significantly different ( P £ 0.004). Genotypic-phenotypic correlations of this SNP were assessed in 10 stable Chinese heart transplant patients. The median AUC(0,4 h) was 11% lower in patients with CC genotype compared with subjects with TT genotype. However, the interpatient variability in AUC(0,4 h) was high in patients, especially in those with CC genotype. Conclusions The distribution of the SNP C3435T in exon 26 in the Chinese and Malay population was found to be similar to the Caucasians whereas the Indians were different. The Asian population also differed significantly from the African and Caucasian population in the distribution of the C3435T SNP. The low frequency of the T allele in the Indian population implies lower expression of P-gp and may have important therapeutic and prognostic implications for use of P-gp dependent drugs in individuals of Indian origin.

Genotype and Allele Frequencies of C3435T Polymorphism of the MDR1 Gene in Various Jewish Populations of Israel

“…Differences in MDR1 C3435T polymorphism between Near Eastern Jews and other Jewish populations (Ashkenazi, North African, Yemenite, and Mediterranean Jews) were statistically significant (P Յ 0.05). The differences between Jewish and non-Jewish populations [19][20][21][22][23][24][25][26] were found to be significant for all such pairs except for Near Eastern Jews and whites.…”

“…21 The Indians had a lower frequency of the C allele (38%) than the Malays (48%) and Chinese (46%). 22 In white populations the frequencies of the C allele were 48% in the UK, 20 46% in the United States, 23 46% in Germany, 24 52% in Spain, 25 and 45.7% in Russia. 26 However, the estimated frequency of the T allele was 53% in the Bulgarian population.…”

Fetal congenital anomalies diagnosed by ultrasound in Asian and non-Asian women

“…Their location in the syncytiotrophoblast plasma membrane at the interface of the maternal and fetal circulations allows these transport proteins to efflux xenobiotics back to the mother and, by offering the fetus protection, may reduce its susceptibility to congenital anomalies. Polymorphisms in the genes for these proteins resulting in low levels of expression have been identified and these have been shown to occur with different frequencies in different ethnic groups (Balram et al 2003;Maekawa et al 2006). No information is available on the effect that consanguinity has on the incidence of these polymorphisms.…”

Correlation of polymorphism C3435T of the MDR-1 gene and the response of primary chemotherapy in women with locally advanced breast cancer

“…In this context, we decided to analyze the significance of SNP C3435T of the MDR-1 gene and its correlation with the clinical and pathological responses in Brazilian patients with breast cancer submitted to primary chemotherapy, through the RFLP technique whose use has been widely reported in the literature due to its simplicity (Cavaco et al, 2003;Balram et al, 2003).…”