Departamento de Ciências Biológicas, Laboratório de Bioquímica, Faculdade de Farmácia da Universidade do Porto, Portugal.
Blood Cells Mol Dis. 2012 Mar 15;48(3):166-72. doi: 10.1016/j.bcmd.2012.01.004. Epub 2012 Feb 9.
The Gilbert syndrome is a benign form of unconjugated hyperbilirubinemia, mainly associated with alterations in UGT1A1 gene. This work investigated the effect of UGT1A1 variants on total bilirubin levels in Gilbert patients (n=45) and healthy controls (n=161). Total bilirubin levels were determined using a colorimetric method; molecular analysis of exons 1-5 and two UGT1A1 promoter regions were performed by direct sequencing and automatic analysis of fragments. Five in silico methods predicted the effect of new identified variants. A significant different allelic distribution, in Gilbert patients and in controls, was found for two promoter polymorphisms. Among patients, 82.2% were homozygous and 17.8% heterozygous for the c.-41_-40dupTA allele; in control group, 9.9% were homozygous and 43.5% heterozygous for this promoter variant, while 46.6% (n=75) presented the [A(TA)6TAA]. For the T>G transition at c.-3279 promoter region, in patients, 86.7% were homozygous and 13.3% heterozygous; in control group, 33.5% were homozygous for the wild type allele, 44.1% were heterozygous and 22.4% homozygous for the mutated allele. The two polymorphisms were in Hardy-Weinberg equilibrium in both groups. Sequencing of UGT1A1 coding region identified nine novel variants, five in patients and four in controls. In silico analysis of these amino acids replacements predicted four of them as benign and three as damaging. In conclusion, we demonstrated that total bilirubin levels are mainly determined by the TA duplication in the TATA-box promoter and by the c.-3279T>G variant. Alterations in the UGT1A1 coding region seem to be associated with increased bilirubin levels, and, therefore, with Gilbert syndrome.
吉尔伯特综合征是一种良性的非结合性高胆红素血症，主要与 UGT1A1 基因的改变有关。本研究调查了 UGT1A1 变异对吉尔伯特患者（n=45）和健康对照组（n=161）总胆红素水平的影响。总胆红素水平采用比色法测定；通过直接测序和片段自动分析对外显子 1-5 和两个 UGT1A1 启动子区域进行分子分析。使用五种计算机方法预测了新鉴定的变异的影响。在吉尔伯特患者和对照组中，两个启动子多态性的等位基因分布存在显著差异。在患者中，82.2%为 c.-41_-40dupTA 等位基因的纯合子，17.8%为杂合子；在对照组中，9.9%为纯合子，43.5%为杂合子，而 46.6%（n=75）为 [A(TA)6TAA]。对于 c.-3279 启动子区域的 T>G 转换，在患者中，86.7%为纯合子，13.3%为杂合子；在对照组中，33.5%为野生型等位基因的纯合子，44.1%为杂合子，22.4%为突变型等位基因的纯合子。两组均符合 Hardy-Weinberg 平衡。UGT1A1 编码区的测序共发现 9 种新变异，其中 5 种在患者中，4 种在对照组中。对这些氨基酸替换的计算机分析预测其中 4 种为良性，3 种为有害。总之，我们证明了总胆红素水平主要由 TATA 盒启动子的 TA 重复和 c.-3279T>G 变异决定。UGT1A1 编码区的改变似乎与胆红素水平升高有关，因此与吉尔伯特综合征有关。
