Cannabinoid receptor 1 gene polymorphism and irritable bowel syndrome in the Korean population: a hypothesis-generating study.
OBJECTIVE
The cannabinoids affect gastrointestinal function and are thought to be involved in the pathogenesis of irritable bowel syndrome (IBS). We hypothesized that genetic variants of the cannabinoid receptor 1 gene (CNR1) might be associated with IBS.


METHODS
One hundred sixty-two IBS patients, who met the Rome II criteria, and 423 healthy controls were subjected to genotyping of polymorphic triplet AAT repeats located in the 3-flanking region of the CNR1 gene.


RESULTS
Allele frequencies of AAT triplet repeats in the CNR1 gene differed markedly between the controls and IBS patients (P<0.01). Controls had a lower frequency of distribution of 10 alleles or more. We divided the alleles into 2 groups (≤ 10 and >10), and 3 genotypes ≤ 10/≤ 10, heterozygote, and >10/>10. The CNR1 having>10/>10 AAT triplet repeats occurred with greater frequency in IBS patients than in the controls (P<0.01). A strong genotype association was observed between the CNR1 >10/>10 genotype and all IBS subtypes compared with controls (P<0.01 for each). The allele frequencies and the CNR1 genotypes did not differ between the 3 IBS subtypes. Symptom scores for abdominal discomfort or pain were higher in patients with the CNR1 >10/>10 genotype than in patients with the other genotypes (P<0.05).


CONCLUSIONS
We found a different distribution of allelic frequency of AAT repeats in the CNR1 gene in healthy controls and IBS patients, and a significant association between the CNR1 >10/>10 genotype and IBS. These results suggest that the CNR1 gene is a potential candidate gene involved in IBS in Korea.
Park
Jae Myung
JM
Division of Gastroenterology, Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea.
Choi
Myung-Gyu
MG
Cho
Yu Kyung
YK
Lee
In Seok
IS
Kim
Sang Woo
SW
Choi
Kyu Yong
KY
Chung
In-Sik
IS
D015746:Abdominal Pain / Q000209:etiology / Q000235:genetics*; D000328:Adult; D000483:Alleles; D044466:Asian People; D016022:Case-Control Studies; D005260:Female; D020022:Genetic Predisposition to Disease; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D043183:Irritable Bowel Syndrome / Q000235:genetics* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic; D043884:Receptor, Cannabinoid, CB1 / Q000235:genetics*; D056910:Republic of Korea
D043884:Receptor, Cannabinoid, CB1