title: Frequency and significance of the novel single nucleotide missense polymorphism Val109Asp in the human gene encoding omentin in Caucasian patients with type 2 diabetes mellitus or chronic inflammatory bowel diseases.
abstract: BACKGROUND
  The omental adipose tissue is pathogenetically involved in both type 2 diabetes mellitus (T2D) and chronic inflammatory bowel diseases (IBD) such as Ulcerative colitis (UC) and Crohn's Disease (CD). Thus, adipokines secreted from omental adipose tissue might play an important role in these diseases. Omentin represents a new adipokine expressed in and secreted by omental adipose tissue. Therefore, it was the aim to investigate the putative role of a newly described sequence missense variation in the human omentin gene.
  
  
  METHODS
  The Val109Asp single nucleotide miss-sense polymorphism and the His86His polymorphism in exon-4 of the omentin gene were newly identified by random sequencing. Only the miss-sense polymorphism was investigated further. Genotyping was performed by restriction fragment length polymorphism (RFLP) analysis of amplified DNA fragments. Three different cohorts of well-characterized individuals were included in the study. 114 patients suffering from T2D, 190 patients suffering from IBD (128 with CD and 62 with UC) and 276 non-diabetic healthy controls without any history for IBD were analyzed.
  
  
  RESULTS
  The following allelic frequencies were determined: controls: Val-allele: 0.26, Asp-allele: 0.74; T2D: Val-allele: 0.3, Asp-allele: 0.7; IBD: Val-allel: 0.31, Asp-allele: 0.69. UC and CD patients did not differ in regard to the allelic frequency. Similarly, controls, T2D patients and IBD patients did not show significant differences in genotype distribution among each other. Disease manifestation and pattern of infestation were not related to genotype subgroups, neither in CD nor in UC. Furthermore, there was no significant association between genotype subgroups and anthropometric or laboratory parameters in T2D patients.
  
  
  CONCLUSIONS
  Based on sequence comparisons and homology searches, the amino acid position 109 is conserved in the omentin gene of humans, mice and chimpanzee but is not completely conserved between other omentin homologous genes. Moreover, position 109 lies outside the fibrinogen domain. Due to these structural features and based on the present data, the Val109Asp sequence variation is more a single nucleotide polymorphism than a real disease-causing mutation.
authors.affiliation: Department of Internal Medicine I, Regensburg University Medical Center, Germany. andreas.schaeffler@klinik.uni-regensburg.de
authors.forename: Andreas
authors.initials: A
authors.lastname: Schäffler
authors.forename: Martina
authors.initials: M
authors.lastname: Zeitoun
authors.forename: Hella
authors.initials: H
authors.lastname: Wobser
authors.forename: Christa
authors.initials: C
authors.lastname: Buechler
authors.forename: Charalampos
authors.initials: C
authors.lastname: Aslanidis
authors.forename: Hans
authors.initials: H
authors.lastname: Herfarth
mesh_terms: D019943:Amino Acid Substitution; D001224:Aspartic Acid; D002908:Chronic Disease; D015331:Cohort Studies; D016207:Cytokines / Q000235:genetics*; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics*; D005260:Female; D058851:GPI-Linked Proteins; D005787:Gene Frequency; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000235:genetics*; D037102:Lectins / Q000235:genetics*; D008297:Male; D020125:Mutation, Missense; D012150:Polymorphism, Restriction Fragment Length; D020641:Polymorphism, Single Nucleotide; D012016:Reference Values; D014633:Valine; D044465:White People
chemical_list: D016207:Cytokines; D058851:GPI-Linked Proteins; C432397:ITLN1 protein, human; D037102:Lectins; D001224:Aspartic Acid; D014633:Valine