Chen Xiao-wen, Yue Li-jie, Li Cheng-rong, Li Chang-gang, Shi Hong-song, Zhang Min
Institute of Pediatrics, Shenzhen Children's Hospital, Shenzhen 518026, China.
Zhonghua Xue Ye Xue Za Zhi. 2008 Jul;29(7):459-63.
To study the relationship between coding single-nucleotide polymorphisms (cSNPs) in the human cytidine deaminase (CDA) gene and cytosine arabinoside (Ara-C) sensitivity in childhood acute leukemia (AL).
cDNAs from 87 leukemia and 199 control blood samples were analyzed for the cSNPs in CDA by PCR-denaturing gradient gel electrophoresis (DGGE) and sequencing. Human CDA genes were transformed into E. coli and yeast, respectively. Catalytic activities of the allele CDA and variant CDAs were determined by HPLC assay. The Ara-C sensitivity of the yeast transformants was measured by growth inhibition assays.
Three known different polymorphisms, namely, 79A/C (K27Q), 208G/A (A70T) and 435T/C (silent) were identified in the coding region of CDA from an investigated Chinese population and displayed allelic frequencies of 12.1%, 0.5% and 76.2%, respectively. No association with susceptibility to disease was observed. Compared with that of CDA70A, the deamination activities for cytidine and Ara-C substrates of the E. coli transformants carrying human CDA70T were decreased by 53% and 63%, respectively (P<0.01), and the Ara-C IC50 value of the yeast transformants was also significantly decreased by 25% [(973 +/- 61) micromol/L to (735 +/- 31) micromol/L, P<0.05].
The 3 known cSNPs and their allelic frequencies of CDA are identified in a Chinese childhood AL. The 208A genotype is shown to be more sensitive to Ara-C than 208G genotype.
研究人类胞苷脱氨酶（CDA）基因编码区单核苷酸多态性（cSNPs）与儿童急性白血病（AL）对阿糖胞苷（Ara-C）敏感性之间的关系。
采用聚合酶链反应-变性梯度凝胶电泳（PCR-DGGE）和测序技术，分析87例白血病患者及199例对照血样中CDA基因的cSNPs。将人类CDA基因分别导入大肠杆菌和酵母中。通过高效液相色谱法（HPLC）检测等位基因CDA和变异型CDA的催化活性。采用生长抑制试验测定酵母转化子对Ara-C的敏感性。
在一个受调查的中国人群中，CDA编码区鉴定出3种已知的不同多态性，即79A/C（K27Q）、208G/A（A70T）和435T/C（沉默突变），其等位基因频率分别为12.1%、0.5%和76.2%。未观察到与疾病易感性的关联。与携带人类CDA70A的大肠杆菌转化子相比，携带人类CDA70T的大肠杆菌转化子对胞苷和Ara-C底物的脱氨活性分别降低了53%和63%（P<0.01），酵母转化子的Ara-C半数抑制浓度（IC50）值也显著降低了25%[从（973±61）μmol/L降至（735±31）μmol/L，P<0.05]。
在中国儿童急性淋巴细胞白血病患者中鉴定出CDA基因的3种已知cSNPs及其等位基因频率。结果表明，208A基因型对Ara-C的敏感性高于208G基因型。
