title: Case-control analysis of SNPs in GLUT4, RBP4 and STRA6: association of SNPs in STRA6 with type 2 diabetes in a South Indian population.
abstract: BACKGROUND
  The inverse relationship between GLUT4 and RBP4 expression is known to play a role in the pathogenesis of type 2 diabetes. Elevated levels of RBP4 were shown to cause insulin resistance in muscles and liver. Identification of STRA6 as a cell surface receptor for RBP4 provides further link in this axis and hence we analyzed SNPs in these three genes for association with type 2 diabetes in a South Indian population.
  
  
  RESULTS
  Selected SNPs in the three genes were analyzed in a total of 2002 individuals belonging to Dravidian ethnicity, South India, by Tetra Primer ARMS PCR or RFLP PCR. Allele frequencies and genotype distribution were calculated in cases and controls and were analyzed for association by Chi-squared test and Logistic regression. Haplotype analysis was carried out for each gene by including all the markers in a single block. We observed a significant association of three SNPs, rs974456, rs736118, and rs4886578 in STRA6 with type 2 diabetes (P = 0.001, OR 0.79[0.69-0.91], P = 0.003, OR 0.81[0.71-0.93], and P = 0.001, OR 0.74[0.62-0.89] respectively). None of the SNPs in RBP4 and GLUT4 showed any association with type 2 diabetes. Haplotype analysis revealed that two common haplotypes H1 (111, P = 0.001, OR 1.23[1.08-1.40]) and H2 (222, P = 0.002 OR 0.73[0.59-0.89]) in STRA6, H6 (2121, P = 0.006, OR 1.69[1.51-2.48]) in RBP4 and H4 (2121, P = 0.01 OR 1.41[1.07-1.85]) in GLUT4 were associated with type 2 diabetes.
  
  
  CONCLUSIONS
  SNPs in STRA6, gene coding the cell surface receptor for RBP4, were significantly associated with type 2 diabetes and further genetic and functional studies are required to understand and ascertain its role in the manifestation of type 2 diabetes.
authors.affiliation: Amrita School of Biotechnology, Amrita Vishwa Vidyapeetham, Kollam, Kerala, India.
authors.forename: Anup Kumar
authors.initials: AK
authors.lastname: Nair
authors.forename: Divya
authors.initials: D
authors.lastname: Sugunan
authors.forename: Harish
authors.initials: H
authors.lastname: Kumar
authors.forename: Gopalakrishnapillai
authors.initials: G
authors.lastname: Anilkumar
mesh_terms: D000368:Aged; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics*; D005260:Female; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease / Q000235:genetics; D005838:Genotype; D051275:Glucose Transporter Type 4 / Q000235:genetics*; D006239:Haplotypes; D006801:Humans; D007194:India; D008297:Male; D008565:Membrane Proteins / Q000235:genetics*; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D054839:Retinol-Binding Proteins, Plasma / Q000235:genetics*
chemical_list: D051275:Glucose Transporter Type 4; D008565:Membrane Proteins; C101326:RBP4 protein, human; D054839:Retinol-Binding Proteins, Plasma; C495692:SLC2A4 protein, human; C519685:STRA6 protein, human