Gong Xiaoqing, Mei Shenghui, Li Xindi, Li Xingang, Zhou Heng, Liu Yonghong, Zhou Anna, Yang Li, Zhao Zhigang, Zhang Xinghu
a Neuroinfection and Neuroimmunology Center , Department of Neurology, Beijing Tiantan Hospital , Capital Medical University , Beijing , P. R. China.
b Department of Neurology, Beijing Shunyi District Hospital , Beijing , P. R. China.
Int J Neurosci. 2018 Jun;128(6):549-553. doi: 10.1080/00207454.2017.1401621. Epub 2017 Dec 1.
Thiopurines are effective drugs in treating neuromyelitis optica spectrum disorders and other diseases. Thiopurines' toxicity is mainly imputed to thiopurine S-methyltransferase activity. In Chinese population, the most common and important variation of thiopurine S-methyltransferase is TPMT*3C (rs1142345). This study aims to reveal the association between thiopurine S-methyltransferase activity and genetic polymorphisms of thiopurine S-methyltransferase in patients with neuromyelitis optica spectrum disorders in China.
A liquid chromatography tandem mass/mass method was used to evaluate the thiopurine S-methyltransferase activity by using 6-mercapthioprine as the substrate in human erythrocyte haemolysate via 1 h incubation at 37 °C to form its methylated product 6-methylmercaptopurine. The amount of 6-methylmercaptopurine was adjusted by haematocrit and normalized to 8 × 10 erythrocytes. The selected polymorphisms of thiopurine S-methyltransferase were identified using MassARRAY system (Sequenom) and multiple SNaPshot technique.
In 69 patients with neuromyelitis optica spectrum disorders, thiopurine S-methyltransferase activity was 80.29-154.53 (127.51 ± 16.83) pmol/h/8 × 10 erythrocytes. TPMT*3C (rs1142345) was associated with lower thiopurine S-methyltransferase activity (BETA = -25.37, P = 0.011). Other selected variants were not associated with thiopurine S-methyltransferase activity.
TPMT*3C affects TPMT activity in Chinese patients with neuromyelitis optica spectrum disorders. Further studies are warranted to confirm the results.
TPRs = thiopurines; NMOSD = neuromyelitis optica spectrum disorders; TPMT = thiopurine S-methyltransferase; LC-MS/MS = liquid chromatography tandem mass/mass; 6-MMP = 6-methylmercaptopurine; IS = internal standard; SNP = single nucleotide polymorphism; MAF = minor allele frequency; HWE = Hardy-Weinberg equilibrium; BETA = regression coefficients; UTR-3 = untranslated region 3.
硫唑嘌呤是治疗视神经脊髓炎谱系障碍及其他疾病的有效药物。硫唑嘌呤的毒性主要归因于硫嘌呤S-甲基转移酶活性。在中国人群中，硫嘌呤S-甲基转移酶最常见且重要的变异是TPMT*3C（rs1142345）。本研究旨在揭示中国视神经脊髓炎谱系障碍患者硫嘌呤S-甲基转移酶活性与硫嘌呤S-甲基转移酶基因多态性之间的关联。
采用液相色谱串联质谱法，以6-巯基嘌呤为底物，在人红细胞溶血产物中于37℃孵育1小时，使其形成甲基化产物6-甲基巯基嘌呤，以此评估硫嘌呤S-甲基转移酶活性。6-甲基巯基嘌呤的量通过血细胞比容进行校正，并标准化为8×10个红细胞。使用MassARRAY系统（Sequenom）和多重SNaPshot技术鉴定硫嘌呤S-甲基转移酶的选定多态性。
69例视神经脊髓炎谱系障碍患者中，硫嘌呤S-甲基转移酶活性为80.29 - 154.53（127.51±16.83）pmol/h/8×10个红细胞。TPMT*3C（rs1142345）与较低的硫嘌呤S-甲基转移酶活性相关（BETA = -25.37，P = 0.011）。其他选定变异与硫嘌呤S-甲基转移酶活性无关。
TPMT*3C影响中国视神经脊髓炎谱系障碍患者的TPMT活性。有必要进行进一步研究以证实该结果。
TPRs = 硫唑嘌呤；NMOSD = 视神经脊髓炎谱系障碍；TPMT = 硫嘌呤S-甲基转移酶；LC-MS/MS = 液相色谱串联质谱；6-MMP = 6-甲基巯基嘌呤；IS = 内标；SNP = 单核苷酸多态性；MAF = 次要等位基因频率；HWE = 哈迪-温伯格平衡；BETA = 回归系数；UTR-3 = 3'非翻译区
