G/T substitution in intron 1 of the UNC13B gene is associated with increased risk of nephropathy in patients with type 1 diabetes.
OBJECTIVE
Genetic and environmental factors modulate the susceptibility to diabetic nephropathy, as initiating and/or progression factors. The objective of the European Rational Approach for the Genetics of Diabetic Complications (EURAGEDIC) study is to identify nephropathy susceptibility genes. We report molecular genetic studies for 127 candidate genes for nephropathy.


METHODS
Polymorphisms were identified through sequencing of promoter, exon, and flanking intron gene regions and a database search. A total of 344 nonredundant SNPs and nonsynonymous variants were tested for association with diabetic nephropathy (persistent albuminuria >/=300 mg/24 h) in a large type 1 diabetes case/control (1,176/1,323) study from three European populations.


RESULTS
Only one SNP, rs2281999, located in the UNC13B gene, was significantly associated with nephropathy after correction for multiple testing. Analyses of 21 additional markers fully characterizing the haplotypic variability of the UNC13B gene showed consistent association of SNP rs13293564 (G/T) located in intron 1 of the gene with nephropathy in the three populations. The odds ratio (OR) for nephropathy associated with the TT genotype was 1.68 (95% CI 1.29-2.19) (P = 1.0 x 10(-4)). This association was replicated in an independent population of 412 case subjects and 614 control subjects (combined OR of 1.63 [95% CI 1.30-2.05], P = 2.3 x 10(-5)).


CONCLUSIONS
We identified a polymorphism in the UNC13B gene associated with nephropathy. UNC13B mediates apopotosis in glomerular cells in the presence of hyperglycemia, an event occurring early in the development of nephropathy. We propose that this polymorphism could be a marker for the initiation of nephropathy. However, further studies are needed to clarify the role of UNC13B in nephropathy.
Trégouet
David-Alexandre
DA
INSERM, Paris, France, and Pierre and Marie Curie-Paris VI University, Paris, France.
Groop
Per-Henrik
PH
McGinn
Steven
S
Forsblom
Carol
C
Hadjadj
Samy
S
Marre
Michel
M
Parving
Hans-Henrik
HH
Tarnow
Lise
L
Telgmann
Ralph
R
Godefroy
Tiphaine
T
Nicaud
Viviane
V
Rousseau
Rachel
R
Parkkonen
Maikki
M
Hoverfält
Anna
A
Gut
Ivo
I
Heath
Simon
S
Matsuda
Fumihiko
F
Cox
Roger
R
Kazeem
Gbenga
G
Farrall
Martin
M
Gauguier
Dominique
D
Brand-Herrmann
Stefan-Martin
SM
Cambien
François
F
Lathrop
Mark
M
Vionnet
Nathalie
N
D000818:Animals; D002460:Cell Line; D045744:Cell Line, Tumor; D003922:Diabetes Mellitus, Type 1 / Q000150:complications / Q000235:genetics*; D003928:Diabetic Nephropathies / Q000209:etiology / Q000235:genetics*; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006239:Haplotypes; D006367:HeLa Cells; D006801:Humans; D007438:Introns / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000235:genetics*; D016017:Odds Ratio; D020641:Polymorphism, Single Nucleotide; D051381:Rats; D012307:Risk Factors
D009419:Nerve Tissue Proteins; C485548:UNC13B protein, human