Lactose intolerance DNA
A DNA variant upstream of the lactase-phlorizin hydrolase gene is associated with lactose intolerance.
Lactose intolerance (lactase non-persistence) is the inability to digest the sugar (lactose) present in dairy products and is caused by a decline in the epithelial production of lactase-phlorizin hydrolase (LPH) in the small intestine. No DNA variation correlating to this lactase non-persistence exists for this enzyme, but in January 14 online Nature Genetics, Nabil Sabri Enattah and colleagues from University of Helsinki, Finland, show that a DNA variant exists upstream of the LCT gene encoding LPH that does associate with the disorder.
Enattah et al. performed a sequence analysis and found a DNA variant, C/T–13910, on 2q21 that completely associates with lactose intolerance in Finnish families and a sample set of 236 individuals from four different populations. They also found a second variant, G/A–22018, 8 kb telomeric to C/T–13910, which is also associated with the trait in 229 of 236 cases (Nat Genet 2002, DOI 10.1038/ng826). In addition, since the C/T–13910 variant occurs in distantly related populations, it would seem to be very old.
These data could be useful in the development of reliable, non-invasive diagnostic tests for lactose intolerance, concluded the authors.