Sequence Analysis of the UGT1A1 Gene Untranslated Region in Chinese Han Population

Abstract

To analyze the 5' and 3'-untranslated region sequences of the UGT1A1 gene in Chinese Han population and to find polymorphic variants within the untranslated region. Genomic DNA was extracted from peripheral leukocytes in 220 healthy Han individuals. The 5' and 3'-untranslated region sequences of the UGT1A1 gene were amplified by polymerase chain reaction, and followed by DNA sequencing. Two polymorphic loci were identified in the 5'-untranslated region of the UGT1A1 gene with -64(G/C) and A(TA)6TAA/A(TA)7TAA in TATAA box region among Chinese Han population. Genotype frequencies were 98.4% (G) and 1.6% (C) in -64 locus of the UGT1A1 gene among the 220 individuals. The allele frequency of A(TA)6TAA and A(TA)7TAA within the promoter region was found to be 93.4% and 6.6%, respectively. Two polymorphic loci of 1813(C/T) and 1941(C/G) were detected in the 3'-untranslated region of the UGT1A1 gene, they showed a homozygous state at two loci with cosegregation pattern at 1813 and 1941 locus. The haplotype frequencies were 73.6% (CC/1813+CC/1941) and 26.4% (TT/1813+GG/1941) for 1813 and 1941 loci in the UGT1A1 gene. Cosegregation pattern, at 1813 and 1941 locus with homozygous state in the 3'-untranslated region of the UGT1A1 gene may be selected from the human genome among Chinese Han population. More studies should be focused on the mechanism of homozygous cosegregation.