Évaluation d'une technique LAMP pour le diagnostic de la prédisposition génétique à l'intolérance au lactose

Lactose, the principle sugar in milk, is a disaccharide hydrolyzed by intestinal lactase into glucose and galactose, which are absorbed directly by diffusion in the intestine. The decline of lactase expression (or hypolactasia) in intestinal microvilli after weaning is a normal phenomenon in mammals known as lactase deficiency. It is observed in nearly 75 % of the world population and is an inherited autosomal recessive trait with incomplete penetrance. It is caused by SNPs in a regulatory element for lactase gene. Two of them are frequently observed in indo-european, sub-saharian and north-african populations: rs4982235 SNP (or -13910 C>T) and rs41380347 (-13915T>G). The aim of this study is to evaluate the analytical performance of a loop-mediated isothermal amplification (LAMP, LC-LacI-LP, Lacar) assay for detecting these SNPs. Analytical performance of the assay was assessed by evaluating within and between-run precision and by comparing the results (n = 34 samples) obtained with the LAMP assay to those obtained with the gold standard (Sanger sequencing of the region of interest). The LAMP assay has good performance (CV < 0.73 % during the between-run study). A perfect agreement with the gold standard method was observed. The presence of other polymorphisms (such as rs41456145, -13913T>C) within the amplified sequence is detected, the misclassification risk is low. This assay can be used for rapidly diagnosing genetic predisposition to lactose intolerance.