The C/C(-13910) and G/G(-22018) genotypes for adult-type hypolactasia are not associated with inflammatory bowel disease.
BACKGROUND
Lactose intolerance with adult-onset is due to the inadequate enzymatic activity of lactasephlorizin hydrolase (LPH). It is frequently seen in patients with Crohn disease, but the mechanism remains to be elucidated. Two DNA genotypes, C/C(-13910) and G/G(-22018), located upstream from the LCT locus, the gene encoding for LPH, were recently identified as representing genetic markers for lactose intolerance. We utilized these two DNA genotypes to study their role in inflammatory bowel disease.


METHODS
We investigated the prevalence of these two DNA variants using specific restriction enzyme digest assays in 166 patients with Crohn disease, in 120 healthy first-degree relatives of Crohn disease patients, in 63 patients with ulcerative colitis and in 187 healthy individuals.


RESULTS
The analysis revealed a frequency of 21.4% of the 2 genotypes for adult-type hypolactasia in our studied German cohort of healthy individuals, which is higher than previously reported (15%) based on the hydrogen (H2) breath test. This might indicate a higher sensitivity of genotyping, but it has to be confirmed in larger cohorts. No significant difference was detectable in the frequency of the C/C(-13910) and G/G(-22018) genotypes in patients with Crohn disease (C/C(-13910): 21.7%; G/G(-22018): 22.3%) compared to first-degree relatives (C/C(-13910): 21.7%; G/G(-22018): 20.8%), patients with ulcerative colitis (C/C(-13910): 20.3%; G/G(-22018): 20.3%) and healthy individuals (C/C(-13910): 21.4%; G/G(-22018): 21.4%).


CONCLUSIONS
The C/C(-13910) and G/G(-22018) genotype of adult-type hypolactasia is not associated with susceptibility to the pathogenesis of Crohn disease and ulcerative colitis.
Büning
C
C
Dept. of Gastroenterology, Hepatology and Endocrinology, Charité, Humboldt University, Berlin, Germany.
Ockenga
J
J
Krüger
S
S
Jurga
J
J
Baier
P
P
Dignass
A
A
Vogel
A
A
Strassburg
C
C
Weltrich
R
R
Genschel
J
J
Lochs
H
H
Schmidt
H
H
D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D000368:Aged; D015331:Cohort Studies; D005260:Female; D005819:Genetic Markers; D005838:Genotype; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000150:complications / Q000235:genetics*; D007787:Lactose Intolerance / Q000150:complications / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D015995:Prevalence
D005819:Genetic Markers