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Open Access Research article

Resequencing of genes for transforming growth factor β1 (TGFB1) type 1 and 2 receptors (TGFBR1, TGFBR2), and association analysis of variants with diabetic nephropathy

Amy Jayne McKnight13*, David A Savage1, Chris C Patterson2, Denise Sadlier4 and A Peter Maxwell1

Author Affiliations

1 Nephrology Research Group, Queen's University of Belfast, Belfast, UK

2 Epidemiology Research Groups, Queen's University of Belfast, Belfast, UK

3 Faculty of Life Sciences, University of Manchester, Manchester, UK

4 Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin, Ireland

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BMC Medical Genetics 2007, 8:5  doi:10.1186/1471-2350-8-5

Published: 23 February 2007

Abstract

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 (TGFβ1) 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 TGFβ1 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 WAVE™ (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 χ2 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 TaqMan™, Invader™ or Pyrosequencing® technology. No significant differences (p > 0.1) were found in genotype or allele distributions between cases and controls for any of the SNPs assessed.

Conclusion

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.