Real-time PCR based detection of the lactase non-persistence associated genetic variant LCT-13910C>T directly from whole blood.

Primary hypolactasia is the main cause of lactose intolerance in adults. It is strongly associated with the single genetic variant LCT-13910C>T, located upstream of the lactase encoding gene. Consequently, analysis of LCT-13910C>T has been recommended as a direct genetic test for the trait. The aim of our study was to develop a TaqMan probe based real-time PCR protocol for the detection of the LCT-13910C>T variant directly from whole blood, circumventing DNA isolation. The LCT-13910C>T variant was determined using the DirectBlood Genotyping PCR Kit (myPOLS Biotec, Konstanz, Germany) together with an in-house TaqMan primer-probe assay. Validity and specificity of the assay was evaluated using EDTA anti-coagulated whole blood samples and corresponding DNA samples. Results from real-time PCR were compared with results obtained by Sanger sequencing from 105 blinded whole blood samples. Validity and specificity of the assay using whole blood were comparable to those using purified genomic DNA as substrate in PCR. Genetic analysis of blood samples were in complete agreement with results obtained by Sanger sequencing. In conclusion, we present a reliable real-time PCR protocol for the detection of the LCT-13910C>T variant directly from whole blood further facilitating diagnosis of primary hypolactasia in symptomatic patients.