Massarray analyzer 4 platform

Genomic DNA was extracted from venous blood leukocytes using standard phenol–chloroform method. Considering potential function and frequency, five SNPs in 5-HTR genes were selected from Single Nucleotide Polymorphism Database (http://www.ncbi.nlm.nih.gov) or previous literature. Of these five SNPs, rs1364043 and rs10042486 are located downstream and upstream, respectively, of 5-HTR1A, rs17289304 and rs6311 lie upstream of 5-HTR2A, and rs6313 is in the 3′ untranslated region of 5-HTR2A. Genotyping of all SNPs was performed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometer using MassARRAY^® Analyzer 4 platform (Sequenom, San Diego, CA, USA). All primers were designed by the accompanying software Spectrodesigner. The polymerase chain reactions (PCRs) were carried out in a total volume of 5 μL, with 10 ng genomic DNA using the cycling conditions recommended by the manufacturer. Multiplexing and homogeneous mass-extension processes were used to produce primer extension products. Detailed information on the primers and polymerase chain reaction conditions are available on request. Genotype determination was performed by researchers blinded to the clinical outcomes of antidepressant treatment.

Genomic DNA was extracted from venous blood leukocytes using the phenol-chloroform method. Considering that the coverage of a gene and minor allele frequency should be above 0.03, glutamate ionotropic receptor AMPA type subunit 1 (GRIA1), GRIK4, and glutamate metabotropic receptor 7 (GRM7) gene were selected on the literature^{[19 (link),22 (link)–25 (link)]} and the NCBI dbSNP database (http://www.ncbi.nlm.nih.gov/SNP) (Table 1). Genotyping of all single nucleotide polymorphisms (SNPs) was performed by a matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometer using the MassARRAY Analyzer 4 platform (Sequenom, CA). All primers were designed by the accompanying software Spectro designer. The polymerase chain reaction (PCRs) were carried out in a total volume of 5 μL, with 10 ng genomic DNA, using the cycling conditions recommended by the manufacturer. Detailed information about primers and PCR conditions is available on request. The determination of genotypes was performed by researchers who were blind to the clinical outcome of the antidepressant treatment. The clinical laboratory of the West China Hospital was participants in it.