title: Weak or no association of TCF7L2 variants with Type 2 diabetes risk in an Arab population.
abstract: BACKGROUND
  The rs7903146 and rs12255372 variants of TCF7L2 have been strongly associated with type 2 diabetes (T2D) risk in most populations studied to date. Meta-analysis of 27 different studies has resulted in a global OR of 1.46 [1.42-1.51] (rs7903146 variant). Thus far, despite a high incidence of T2D, the role of this variant in Arabs has not been established.
  
  
  METHODS
  We performed a case-control association study using 522 Saudi T2D patients (WHO criteria), and 346 controls (age > 60; fasting plasma glucose < 7 mmol/L). Genotyping was performed by pyrosequencing. Statistical analyses were performed using SPSS version 13.0 for Windows (SPSS, Chicago, IL, USA).
  
  
  RESULTS
  For rs7903146, the T allele frequency of the cases (0.415) was not different from that observed in the controls (0.405). The crude odds ratio (OR) was 1.04 with a 95% CI of 0.86-1.27 (P = 0.675). For rs12255372, the T allele frequency of the cases (0.368) was not different from that observed in the controls (0.355). Retrospective power calculations based upon an OR of 1.46 reported in a comprehensive meta-analysis of TCF7L2 risk, indicated this study was sufficiently powered (96.92%; alpha = 0.05) to detect an effect of similar magnitude to that reported for rs7903146.
  
  
  CONCLUSIONS
  Our study is consistent with weak or no association of T2D in Arabs with the two TCF7L2 variants, however it cannot rule out an effect of other SNPs in this gene. Future studies in this population are required to confirm our findings and may indicate the presence of yet to be defined genetic risk factors for T2D.
authors.affiliation: Saudi Diagnostic Laboratory, Research Centre, King Faisal Specialist Hopital and Research Center, Riyadh, Kingdom of Saudi Arabia. oalsmadi@kfshrc.edu.sa
authors.forename: Osama
authors.initials: O
authors.lastname: Alsmadi
authors.forename: Khalid
authors.initials: K
authors.lastname: Al-Rubeaan
authors.forename: Gamal
authors.initials: G
authors.lastname: Mohamed
authors.forename: Fadi
authors.initials: F
authors.lastname: Alkayal
authors.forename: Haya
authors.initials: H
authors.lastname: Al-Saud
authors.forename: Nouran Abu
authors.initials: NA
authors.lastname: Al-Saud
authors.forename: Nasser
authors.initials: N
authors.lastname: Al-Daghri
authors.forename: Shahinaz
authors.initials: S
authors.lastname: Mohammad
authors.forename: Brian F
authors.initials: BF
authors.lastname: Meyer
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000483:Alleles; D018912:Arabs; D016022:Case-Control Studies; D015331:Cohort Studies; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics*; D005260:Female; D005787:Gene Frequency; D005819:Genetic Markers; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D012307:Risk Factors; D012529:Saudi Arabia; D017422:Sequence Analysis, DNA; D051820:TCF Transcription Factors / Q000235:genetics*; D058118:Transcription Factor 7-Like 2 Protein
chemical_list: D005819:Genetic Markers; D051820:TCF Transcription Factors; C544894:TCF7L2 protein, human; D058118:Transcription Factor 7-Like 2 Protein