Objective: Adult lactose intolerance, which affects the majority of the population in the world, has been associated with a single nucleotide polymorphism, C-13910T, located upstream of the lactase gene.
Material and methods: Adult patients undergoing lactose tolerance tests with lactose challenge and plasma glucose measurements were included in the study comprising 44 Swedes and 7 non-Swedish individuals. A real-time PCR method was established for the genotyping.
Results: Out of 51 patients 48 had concordant results on genotyping and lactose tolerance tests, e.g. -13910T/T and -13910C/T genotypes had high glucose elevations. All patients with the heterozygous genotype, -13910C/T, had high glucose elevations, and no gene-dose relationship was observed when comparing maximal glucose increases for cases with -13910C/T and -13910T/T genotypes.
Conclusions: Genotyping could replace lactose challenge as a first-stage screening test in adults of European descent, but should be used together with tolerance tests in children and patients where secondary lactose intolerance is suspected.