Association of aldose reductase gene Z+2 polymorphism with reduced susceptibility to diabetic nephropathy in Caucasian Type 1 diabetic patients.
OBJECTIVE
The Z-2 allele of the (AC)n polymorphism in the aldose reductase gene (ALR2) confers increased risk of microvascular diabetic complications, whereas the Z+2 allele has been proposed to be a marker of protection. However data are conflicting. Therefore, we investigated whether this polymorphism is associated with diabetic nephropathy and retinopathy in Type 1 diabetes mellitus in a large case-control study and a family-based analysis.


METHODS
A total of 431 Type 1 diabetic patients with diabetic nephropathy and 468 patients with longstanding Type 1 diabetes and persistent normoalbuminuria were genotyped for the case-control study. In addition, 102 case trios and 98 control trios were genotyped for a family-based study.


RESULTS
Thirteen different alleles were identified. In the case-control study, the Z+2 allele frequency was significantly higher in the normoalbuminuric diabetic than in patients with diabetic nephropathy (0.17 vs. 0.11, P = 0.008), suggesting a protective function of the Z+2 allele. No significant increase in the frequency of the putative risk allele Z-2 was found in patients with diabetic nephropathy vs. controls (0.39 vs. 0.36). No association with diabetic retinopathy was found. Although the results of the transmission of the Z-2 and Z+2 alleles in the independent family-based study were consistent with the association study, the number of informative families was limited and thus differences were not statistically significant.


CONCLUSIONS
The Z+2 allele of the ALR2 promoter polymorphism is associated with a reduced susceptibility to diabetic nephropathy in Danish Type 1 diabetic patients, suggesting a minor role for the polyol pathway in the pathogenesis of diabetic kidney disease. No association of the ALR2 polymorphism with diabetic retinopathy was found.
Lajer
M
M
Steno Diabetes Centre, Gentofte, Denmark. mlaj@novonordisk.com
Tarnow
L
L
Fleckner
J
J
Hansen
B V
BV
Edwards
D G
DG
Parving
H-H
HH
Boel
E
E
D000449:Aldehyde Reductase / Q000235:genetics*; D016022:Case-Control Studies; D003922:Diabetes Mellitus, Type 1 / Q000201:enzymology / Q000235:genetics*; D003928:Diabetic Nephropathies / Q000201:enzymology / Q000235:genetics*; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic / Q000235:genetics*
D000449:Aldehyde Reductase