Genotyping of the LCT (T/C-13910) polymorphism on the LightCycler using fluorescent hybridisation probes Genotypisierung des LCT (T/C-13910)-Polymorphismus am LightCycler mittels fluoreszenzmarkierter Hybridisierungssonden

Primary adult-type hypolactasia is a hereditary metabolic condition which leads to clinical manifestation usually during early adulthood and is frequently associated with clinical symptoms of lactose intolerance. The prevalence of adult-type hypolactasia varies extremely in different populations; in Central Europe, it is about 15–40%. The CC homozygous genotype of the LCT (T/C-13910) polymorphism on chromosome 2q21 is strongly associated with primary adult-type hypolactasia. For rapid genotyping by real-time PCR we developed a genetic test using fluorescently labeled hybridization probes. We genotyped 60 patients with clinically suspected lactose intolerance and compared the results of the new genetic test with clinical data and lactose H2 breath test results, the clinically most widely used non-invasive test for the diagnosis of lactose malabsorption. 80% of the CC individuals were lactose malabsorbers, whereas only 30% of the TC or TT individuals were classified as lactose malabsorbers according to their H2 breath test results. The genetic test ist suitable for routine clinical applications and of great value for the reliable differentiation between lactose malabsorbers with adult-type hypolactasia and patients with secondary hypolactasia due to different gastrointestinal disorders or small intestinal bacterial overgrowth.