Interference of homologous sequences on the SNP study of CYP2A13 gene / 中国肺癌杂志

<p><b>BACKGROUND AND OBJECTIVE</b>It has been proven that cytochrome P450 enzyme 2A13 (CYP2A13) played an important role in the association between single nucleotide polymorphisms (SNP) and human diseases. Cytochrome P450 enzymes are a group of isoenzymes, whose sequence homology may interfere with the study for SNP. The aim of this study is to explore the interference on the SNP study of CYP2A13 caused by homologous sequences.</p><p><b>METHODS</b>Taqman probe was applied to detect distribution of rs8192789 sites in 573 subjects, and BLAST method was used to analyze the amplified sequences. Partial sequences of CYP2A13 were emplified by PCR from 60 cases. The emplified sequences were TA cloned and sequenced.</p><p><b>RESULTS</b>For rs8192789 loci in 573 cases, only 3 cases were TT, while the rest were CT heterozygotes, which was caused by homologous sequences. There are a large number of overlapping peaks in identical sequences of 60 cases, and the SNP of 101 amino acid site reported in the SNP database is not found. The cloned sequences are 247 bp, 235 bp fragments.</p><p><b>CONCLUSION</b>The homologous sequences may interfere the study for SNP of CYP2A13, and some SNP may not exist.</p>

Association between GSTM1 genetic polymorphism and lung cancer risk by SYBR green I real-time PCR assay / 中国肺癌杂志

<p><b>BACKGROUND AND OBJECTIVE</b>Glutathione S-transferase M1 (GSTM1) is an important phase II metabolic enzyme gene which involves metabolism of various carcinogens in human body. Many studies showed that GSTM1 genetic polymorphism was associated with lung cancer risk. The aim of this study is to investigate the relationship between GSTM1 genetic polymorphism and lung cancer risk among Han nationality population in Tianjin district.</p><p><b>METHODS</b>GSTM1 genetic polymorphism was detected by melting curve analysis of SYBR green I real-time PCR assay. Two hundred and sixty-five histological confirmed lung cancer patients and 307 health controls were recruited in this case-control study and the relationship between GSTM1 genetic polymorphism and lung cancer riskwas investigated.</p><p><b>RESULTS</b>(1) The frequency of the GSTMI(-) in lung cancer and control groups was 56.6% and 57.0% respectively, and no significant difference was found between the distribution of the GSTM1 (-) genotype in the two groups (chi2 = 0.831, P = 0.362). (2) When considered the GSTM1(+) genotype as reference, there was no overall statistically increased lung cancer risk for carriers with the GSTM1(-) genotype adjusted by age, gender and smoking status (OR = 0.840, 95% CI: 0.578-1.221, P = 0.362). (3) The frequency of the GSTM1(-) genotype for squamous cell carcinoma, adenocarcinoma, SCLC and other histological types was 65.8%, 48.5%, 47.8% and 52.2% respectively, compared with the control group, no statistically increased lung cancer risk was observed (P > 0.05).</p><p><b>CONCLUSION</b>No evidence is found between GSTMI genetic polymorphism and lung cancer risk among Han nationality population in Tianjin district.</p>