City, CA) at 94°C for 12 minutes followed by 40 cycles of 94°C for 30 sec., 55°C for 30 sec., 72°C for 30 sec., with a final extension at 72°C for 10 minutes. PCR products for the individual markers were pooled before electrophoresis on a 3730XL DNA Analyzer (Applied Biosystems, Foster City, CA). Data were collected and analyzed with GeneMapper software (Applied Biosystems, Foster City, CA) that calculates fragment length in reference to an internal lane standard Genescan-500 labeled with LIZ. All genotypes were manually checked. Duffy Antigen SNP rs2814778 was genotyped using TaqMan® Pre-Designed SNP Genotyping Assay (Applied Biosystems, Foster City, CA). Samples were PCR amplified in 5μl reaction volume containing 0.125μl 40X assay mix, 2.5μl Master Mix and 8ng DNA. PCR and end point detection of fluorescence were carried out in an ABI 7900HT Sequence Detection System (Applied Biosystems, Foster City, CA). Fluorescence data were analyzed with SDS v2.1 software. As a quality control, 20% of genotypes were repeated. PCR amplification failed or provided ambiguous genotype results in 4% of population markers and 2% of Duffy Antigen SNP.
