SNPs selection and genotyping
SNPs were selected based on the following criteria. Firstly, SNPs located within TBXAS1 gene with a MAF of > 5% in CHB according to the NCBI HapMap Database (http://hapmap.ncbi.nlm.nih.gov/). Secondly, selected SNPs were entered into Haploview Ver. 4.2 software [26] to obtain tag SNPs. Thirdly, no studies have addressed the distribution regularities of the SNPs, or their relationship with MS, in Chinese population. At last, the SNP rs3801150 was finally selected and genotyped.
Genomic DNAs were extracted from blood by Magen blood DNA kit D3133-03 (Magen, Guangzhou, China) following the manufacturer’s protocols. SNP at NC_000007.14:g.139985896C>T was genotyped in BGI, Shenzhen, China by Sequenom MassArray system (Sequenom, San Diego, CA). The PCR reaction was conducted using GeneAmp PCR System 9700 (ABI, Foster City, CA, USA). And mass determination was performed with matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry [24]. Data were collected by Spectro TYPER Ver. 4.0 software (Sequenom, San Diego, CA). Call rates of genotyping were > 95% for the SNP. A total of 120 (5%) samples were randomly selected for the concordance test, and the concordance rates were > 99% for the SNP.