P903 Lactase non-persistence and Inflammatory Bowel Disease in a Basque cohort

Garcia-Etxebarria, K.(1,2)*;Merino, O.(3);Ezcurra, A.(4);Segues, N.(4);Arzallus, T.(4);Marigorta, U.M.(5);Vignau, R.(4);Bujanda, L.(2,4);

(1)Biodonostia HRI, Gastrointestinal Genetics Group, Donostia-San Sebastián, Spain;(2)Centro de Investigación Biomédica en Red, Enfermedades Hepáticas y Digestivas, Barcelona, Spain;(3)Hospital Universitario Cruces, Gastroenterology Department, Barakaldo, Spain;(4)Biodonostia HRI, Gastrointestinal Disease Group, Donostia - San Sebastián, Spain;(5)Center for Cooperative Research in Biosciences CIC bioGUNE, Integrative Genomics Lab, Derio, Spain;


Patients with inflammatory bowel disease (IBD) experience symptoms (e. g. abdominal pain, bloating, or diarrhoea) that could be partially due to food intolerances or malabsorption. Thus, those patients could restrict some foods in their diet to avoid the symptoms. Among others, they could restrict their intake of dairy products, since lactose intolerance is one of the most prevalent intolerances. Although the role of lactose intolerance in IBD has been studied, the results are not entirely conclusive.

Recently, we analysed the genetic basis of IBD in a Basque cohort and we have taken advantage of the data we had available to study the role of the lactase non-persistence in IBD.


The genotype of the single nucleotide polymorphism (SNP) rs4988235 was retrieved from 1427 individuals (492 IBD cases and 935 controls from the general population) studied previously in a Basque cohort. The G allele of that SNP is associated with the non-persistence of lactase and the individuals were classified as carriers and non-carriers of that allele.

The effect of the carriership of that allele in the risk of IBD was analysed through generalized linear models, adjusting by the first four principal components of the genetic distance between individuals. In addition, IBD subtypes and behaviour and location of Crohn’s Disease (CD) were analysed.


On the whole, 1089 individuals (76.31%) were carriers of the non-persistent lactase allele. This high prevalence is due to the effect of the mixture of modern European (where the 68.08% was carrier) and ancient European (87.45%) ancestries of the actual Basque population.

Although there is a trend, the carriers of the non-persistent lactase allele did not show a significantly higher risk of developing IBD (OR=1.5, 95%CI: 0.9-2.5, P=0.0749). When subtypes were analysed, there was no higher risk of developing Ulcerative Colitis (P=0.4261), while the risk of developing CD approached formal significance (OR=1.4, 95%CI: 0.99-1.9, P= 0.0584).

Considering this result, we further analysed the effect of the non-persistent lactase allele regarding the behaviour or location of CD. The carriers of the non-persistent lactase allele had a higher risk of penetrating CD (OR=2.7, 95%CI: 1.1-7.9, P=0.0437) and of colonic CD (OR=4.7, 95%CI: 1.4-29.4, P=0.0375).


Although the sample size was limited, the carriers of the non-persistent lactase allele were higher in penetrating CD and colonic CD than in the general population. Thus, lactose consumption could affect those cases of CD and, therefore, follow-up analyses are needed to validate these results.