Resequencing of genes for transforming growth factor beta1 (TGFB1) type 1 and 2 receptors (TGFBR1, TGFBR2), and association analysis of variants with diabetic nephropathy.
BACKGROUND
Diabetic nephropathy is the leading cause of end stage renal failure in the western world. There is substantial epidemiological evidence supporting a genetic predisposition to diabetic nephropathy, however the exact molecular mechanisms remain unknown. Transforming growth factor (TGFbeta1) is a crucial mediator in the pathogenesis of diabetic nephropathy.


METHODS
We investigated the role of five known single nucleotide polymorphisms (SNPs) in the TGFB1 gene for their association with diabetic nephropathy in an Irish, type 1 diabetic case (n = 272) control (n = 367) collection. The activity of TGFbeta1 is facilitated by the action of type 1 and type 2 receptors, with both receptor genes (TGFBR1 and TGFBR2) shown to be upregulated in diabetic kidney disease. We therefore screened TGFBR1 and TGFBR2 genes for genomic variants using WAVEtrade mark (dHPLC) technology and confirmed variants by direct capillary sequencing. Allele frequencies were determined in forty-eight healthy individuals. Data for all SNPs was assessed for Hardy Weinberg equilibrium, with genotypes and allele frequencies compared using the chi2 test for contingency tables. Patterns of linkage disequilibrium were established and common haplotypes estimated.


RESULTS
Fifteen variants were identified in these genes, seven of which are novel, and putatively functional SNPs were subsequently genotyped using TaqMantrade mark, Invadertrade mark or Pyrosequencing(R) technology. No significant differences (p > 0.1) were found in genotype or allele distributions between cases and controls for any of the SNPs assessed.


CONCLUSIONS
Our results suggest common variants in TGFB1, TGFBR1 and TGFBR2 genes do not strongly influence genetic susceptibility to diabetic nephropathy in an Irish Caucasian population.
McKnight
Amy Jayne
AJ
Nephrology Research Group, Queen's University of Belfast, Belfast, UK. a.j.mcknight@lineone.net
Savage
David A
DA
Patterson
Chris C
CC
Sadlier
Denise
D
Maxwell
A Peter
AP
D030201:Activin Receptors, Type I / Q000235:genetics*; D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D004252:DNA Mutational Analysis; D003922:Diabetes Mellitus, Type 1 / Q000235:genetics*; D003928:Diabetic Nephropathies / Q000235:genetics*; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D016133:Polymerase Chain Reaction; D020641:Polymorphism, Single Nucleotide; D017346:Protein Serine-Threonine Kinases; D000077293:Receptor, Transforming Growth Factor-beta Type I; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta / Q000235:genetics*; D053773:Transforming Growth Factor beta1 / Q000235:genetics*
D018125:Receptors, Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D017346:Protein Serine-Threonine Kinases; D030201:Activin Receptors, Type I; D000077293:Receptor, Transforming Growth Factor-beta Type I; D000077294:Receptor, Transforming Growth Factor-beta Type II; C000625841:TGFBR1 protein, human