Single nucleotide polymorphism detection: allelic discrimination using TaqMan

Candidate gene studies are one of the most widely used approaches in the dissection of the genetic basis of disease. High-throughput methods for genotyping single nucleotide polymorphisms (SNPs) are necessary to perform large-scale association studies. We describe the use of the TaqMan or 5' nuclease allelic discrimination assay for genotyping polymorphisms of the collagen I alpha 1 (COLIA1) and vitamin D receptor (VDR) genes. The basis for the assay is an allele specific oligonucleotide probe, labelled with a fluorescent reporter dye and a quencher dye, which is cleaved during the amplification process generating an increase in the intensity of fluorescence related to the accumulation of PCR product which is measured directly in the reaction well. Suitable for the discrimination of alleles differing by a single base change, this technique is robust, accurate, cost effective, and sufficiently high-throughput for a medium sized laboratory performing association analyses.