INTRODUCTION TO SNP GENOTYPING BY REAL-TIME PCR OLIVIA MIHAELA POPA, MIHAI BOJINCÃ, VIOLETA BOJINCÃ, CLAUDIA CIOFU, CONSTANTIN BÂRÃ, LUIS OVIDIU POPA Abstract. In this work we present an introduction in the SNP genotyping technique through real-time PCR. SNP genotyping is largely used in medicine, but it is becoming increasingly important in various fields of today biology, as molecular ecology, evolution, biological conservation. The real-time PCR is a high throughput genotyping technique, and efficient protocols were recently developed, both from the technical and financial point of view. Résumé. On présente une introduction dans la technique de genotypage des polymorphismes ponctuels (SNP) avec la technologie de PCR en temps réel. Cette dernière technologie est largement utilisé en médecine, mais il devient de plus en plus important dans les études d’écologie moléculaire, d’évolution et de conservation biologique. La technique Real-Time PCR permet une analyse rapide (en temps réél) et simultanée des polymorphismes SNP, tandis que les progrés enregistrés ces derniers temps permettent le développement de protocoles efficients tant du point de vue technique que financier. Key words: SNP, Real-Time PCR, Genotyping. INTRODUCTION The term genotyping refers to a variety of applications used to analyze differences in genomic DNA between individuals, applications associated with human, animals, plants, microbes or viral samples. There are a lot of techniques and platforms suitable for genotyping, but they are all based on the principles of a few basic technologies: • PCR-based methods and primer extension technologies; • Hybridization technologies including arrays; • Fragment length polymorphism analysis; • Sequencing. No matter what method is used and for what type of organism, the challenges associated with genotyping applications are similar and include important factors such as sample quality and amount, sensitivity, reliability, time to result and overall cost. A single nucleotide polymorphism (SNP) is a DNA polymorphisms at the level of a single nucleotide. This sort of DNA variation occurs with a general frequency of about 1 every 1000bp in the human genome (Sachidanandam et al., 2001). The SNPs are not evenly distributed across the human genome, being more frequent in non-coding regions than in coding regions (Li & Sadler, 1991). The SNPs in the non-coding regions can be used as molecular markers in evolutionary studies. The SNPs in the coding regions of the genome can affect gene functions, protein structure or expression and for these reasons they are used as markers in genetic disease studies (Kim & Mishra, 2007). Because of this use of SNPs as molecular markers efforts have been made to develop high-throughput genotyping technologies. Travaux du Muséum National d’Histoire Naturelle «Grigore Antipa» Vol. LII pp. 515–522 © Octobre 2009