PT  - JOURNAL ARTICLE
AU  - Nahoko Kaniwa
AU  - Kouichi Kurose
AU  - Hideto Jinno
AU  - Toshiko Tanaka-Kagawa
AU  - Yoshiro Saito
AU  - Mayumi Saeki
AU  - Jun-ichi Sawada
AU  - Masahiro Tohkin
AU  - Ryuichi Hasegawa
TI  - RACIAL VARIABILITY IN HAPLOTYPE FREQUENCIES OF <em>UGT1A1</em> AND GLUCURONIDATION ACTIVITY OF A NOVEL SINGLE NUCLEOTIDE POLYMORPHISM 686C> T (P229L) FOUND IN AN AFRICAN-AMERICAN
AID  - 10.1124/dmd.104.001800
DP  - 2005 Mar 01
TA  - Drug Metabolism and Disposition
PG  - 458--465
VI  - 33
IP  - 3
4099  - http://dmd.aspetjournals.org/content/33/3/458.short
4100  - http://dmd.aspetjournals.org/content/33/3/458.full
SO  - Drug Metab Dispos2005 Mar 01; 33
AB  - Ethnic differences in genetic polymorphisms in UDP-glucuronosyltransferase 1A1 (UGT1A1) were investigated among African-Americans, Caucasians, and Japanese using samples obtained from 150 individuals for each population. Genotyping of –3279T>G in the phenobarbital-responsive enhancer module, TA repeats in the TATA box, 211G>A (G71R) and 686C>A (P229Q) in exon 1, and three single nucleotide polymorphisms (SNPs) (1813C> T, 1941C>G, and 2042C>G) in the 3′-untranslated region in exon 5 was performed. Eight haplotypes of block 1 (exon 1 and its 5′-flanking region) harboring the first four variations were assigned to each individual. The dominant haplotype for African-Americans was *28b (–3279G;TA7; 211G;686C) (0.446), whereas that for the Japanese was *1a (–3279T; TA6;211G;686C) (0.610). Frequencies of the two haplotypes *1a and *28b were comparable in Caucasians. Haplotype *6a (–3279T;TA6; 211A;686C) was characteristic of the Japanese, whereas haplotypes *36b and *37b (–3279T;TA5 and TA8;211G;686C) were found mostly in African-Americans. Although the three SNPs in block 2 (exons 2–5) were in complete linkage in the Japanese, they were not completely linked in African-Americans or Caucasians. These differences in haplotype distribution patterns among the three populations suggest the possibility of ethnic differences in toxicity profiles of drugs detoxicated by UGT1A1. A novel SNP, 686C>T (P229L), was found in an African-American. The intrinsic clearance of 7-ethyl-10-hydroxycamptothecin (SN-38) by P229L UGT1A1 expressed in COS-1 cells was about 3% of the wild type. The results of Western blotting and real-time reverse transcription-polymerase chain reaction suggest that the low glucuronidation activity of the variant was partly due to its low stability. The variation 686C>T may cause high toxicity during 7-ethyl-10-[4-(1-piperidino)-1-piperidino]carbonyloxycamptothecin (CPT-11) therapy or hyperbilirubinemia in patients. The American Society for Pharmacology and Experimental Therapeutics