MICA, MICB and C1_4_1 polymorphism in Crohn's disease and ulcerative colitis.
MICA and MICB belong to a multicopy gene family located in the major histocompatibility complex (MHC) class I region near the HLA-B gene. They encode for MHC class I molecules, which are induced by stress factors like infection, heat shock or neoplastic transformation and which are mainly expressed on gastrointestinal epithelium. They are recognized by gammadelta T lymphocytes and natural killer (NK) cells. Additionally they are located within a linkage region on chromosome 6p around HLA-B and TNFalpha. Thus the polymorphic MICA and MICB genes are excellent candidate genes for providing the genetic background of inflammatory bowel disease. A strong association of allele A6 of the MICA exon 5 trinucleotide microsatellite polymorphism with ulcerative colitis has been found in Japanese patients. Therefore, we have analysed the MICA exon 5 polymorphism, the MICB intron 1 dinucleotide polymorphism and in addition the tetranucleotide polymorphism C1_4_1, which is located between the MICA gene and the HLA-B gene, in patients of Caucasoid origin with Crohn's disease (n=94) and ulcerative colitis (n=94). In this study we could not find any associations of particular alleles of the MICA, MICB and C1_4_1 polymorphisms with Crohn's disease or ulcerative colitis. We could also not discover any associations of specific two-point or three-point haplotypes with these diseases. Thus it is unlikely that the MICA and MICB genes are involved in causing susceptibility for inflammatory bowel disease, although it cannot be excluded that a weak association could be identified in a larger patient sample.
Glas
J
J
Institut für Anthropologie und Humangenetik, LMU München, Munich, Germany. lfi@lrz.uni-muenchen.de
Martin
K
K
Brünnler
G
G
Kopp
R
R
Folwaczny
C
C
Weiss
E H
EH
Albert
E D
ED
D003093:Colitis, Ulcerative / Q000235:genetics*; D003424:Crohn Disease / Q000235:genetics*; D005260:Female; D005787:Gene Frequency / Q000235:genetics; D020022:Genetic Predisposition to Disease; D006239:Haplotypes / Q000235:genetics; D015395:Histocompatibility Antigens Class I / Q000235:genetics*; D006801:Humans; D015810:Linkage Disequilibrium; D008297:Male; D011110:Polymorphism, Genetic; D044465:White People
D015395:Histocompatibility Antigens Class I; C099187:MHC class I-related chain A; C098080:MICB antigen