Genotyping of the lactase-phlorizin hydrolase C/T_-13910 polymorphism by means of a new rapid denaturing high-performance liquid chromatography-based assay in healthy subjects and colorectal cancer patients

Adult-type hypolactasia results from the progressive decline of lactase-phlorizin hydrolase activity in enterocytes after weaning. Lactase nonpersistence may determine a primary lactose intolerance with reduced diary product consumption, which is possibly related to an increased risk of colon cancer. Recently, a genetic variant C/T-13910 upstream of the lactase-phlorizin hydrolase (LCT) gene has been strongly correlated with the lactase persistence/nonpersistence trait in both family and case-control studies. The authors validate a denaturing high-performance liquid chromatography (dHPLC)-based assay versus conventional genotype sequencing in detecting the C/T-13910 polymorphism of LCT and evaluate its prevalence in 2 different Italian geographical areas and in colorectal cancer patients. DNA samples of 157 healthy subjects and 124 colon cancer patients from Apulia and of 97 healthy subjects from Sardinia were evaluated for the C/T-13910 polymorphism by dHPLC, sequencing, and restriction fragment length polymorphism (RFLP). Under optimized conditions, dHPLC was as sensitive as DNA sequencing and detected a new genetic variant (T/C-13913) in 2 individuals that was not identified by RFLP assay. Frequency of lactase nonpersistence genotype (C/C-13910) was similar in healthy subjects from 2 different Italian geographical areas and not increased in patients with colorectal cancer. The results indicate that the dHPLC method may be used as a rapid, noninvasive, and laborsaving screening tool for genotyping C/T-13910 polymorphism, with high success, low cost, and reproducibility.