ABSTRACT
When developing a genotyping assay by Pyrosequencing(trade mark) technology for the RFC1 (SLC19A1) c.80G>A polymorphism (rs1051266), unequal peak heights in the pyrograms were observed, probably due to unequal amplification of the mutated and wild-type alleles. This rarely occurring problem could potentially render assignment of heterozygous genotypes uncertain. When the PCR conditions were studied, it was found that substitution of the dGTP nucleotide in the master mix by dGTP and dITP in proportion 1:1 largely overcame this problem. Heat denaturation of the DNA at 95 degrees C before PCR also counteracted the problem. A combination of these two modifications of the standard pyrosequencing PCR protocol gave the best results. We conclude that, with these modifications, the RFC1 c.80G>A SNP can be reliably assayed by pyrosequencing.
Subject(s)
Membrane Transport Proteins/genetics , Polymerase Chain Reaction/methods , Polymorphism, Genetic , Aged , Base Sequence , DNA Primers , Female , Genotype , Humans , Male , Nucleic Acid DenaturationABSTRACT
The 776C>G polymorphism of the Transcobalamin II gene is located in a GC-rich region and TaqMan real-time polymerase chain reaction (PCR) does not yield satisfactory genotyping results. We therefore hypothesized that a method based on DNA sequencing would be needed for this single nucleotide polymorphism (SNP) analysis; Pyrosequencing technology was tested for this purpose. A Pyrosequencing protocol was developed, optimized and applied to a sample of 389 Swedish senior citizens. The three genotypes CC, CG, and GG consistently yielded typical programs that were readily distinguishable from each other. The prevalence of the mutated allele in the studied Swedish population was q=0.445. It is concluded that the TC II 776C>G polymorphism can be reliably genotyped by Pyrosequencing technology.