title: Genotyping of the lactase-phlorizin hydrolase -13910 polymorphism by LightCycler PCR and implications for the diagnosis of lactose intolerance.
abstract: BACKGROUND
  Hypolactasia and lactose intolerance are common conditions worldwide. Hypolactasia seems to be strongly correlated with genotype C/C of the genetic variant C-->T(-13910) upstream of the lactase phlorizin hydrolase (LPH) gene. We developed a rapid genotyping assay for LPH C-->T(-13910) and investigated the relationship of positive lactose breath hydrogen test (LBHT) results suggesting lactose intolerance with LPH C-->T(-13910) genotype.
  
  
  METHODS
  Using automated DNA purification on the MagNA Pure LC and real-time PCR on the LightCycler, we examined samples from 220 individuals to estimate genotype frequencies; we then determined LPH C-->T(-13910) genotype in samples from 54 Caucasian patients with a positive LBHT result and symptoms of lactose intolerance.
  
  
  RESULTS
  Genotyping of 220 individuals revealed frequencies of 21.4%, 41.8%, and 36.8% for genotypes C/C, C/T, and T/T. Of the patients with positive LBHT results, only 50% had the C/C genotype suggestive of primary adult hypolactasia in our study population. The other patients had various degrees of secondary hypolactasia or symptoms of lactose intolerance. Patients with C/C genotype had a mean (SD) peak H2 increase in the LBHT [108 (58) ppm] that was significantly higher than in patients with the C/T [65 (54) ppm] and T/T [44 (34) ppm] genotypes.
  
  
  CONCLUSIONS
  The new real-time PCR assay provides a rapid, labor-saving means for the genotyping of LPH C-->T(-13910). Use of the assay may assist in differentiating patients with primary hypolactasia from those with secondary hypolactasia and lactose intolerance, who may need further clinical examinations to diagnose their underlying primary diseases.
authors.affiliation: Institute of Laboratory Medicine, General Hospital Linz, Linz, Austria.
authors.forename: Gerd
authors.initials: G
authors.lastname: Bodlaj
authors.forename: Markus
authors.initials: M
authors.lastname: Stöcher
authors.forename: Peter
authors.initials: P
authors.lastname: Hufnagl
authors.forename: Rainer
authors.initials: R
authors.lastname: Hubmann
authors.forename: Georg
authors.initials: G
authors.lastname: Biesenbach
authors.forename: Herbert
authors.initials: H
authors.lastname: Stekel
authors.forename: Jörg
authors.initials: J
authors.lastname: Berg
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001944:Breath Tests; D005260:Female; D005838:Genotype; D006801:Humans; D010694:Lactase-Phlorizin Hydrolase / Q000032:analysis / Q000235:genetics*; D007787:Lactose Intolerance / Q000175:diagnosis* / Q000201:enzymology; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D012189:Retrospective Studies
chemical_list: D010694:Lactase-Phlorizin Hydrolase