Association between LTA, TNF and AGER polymorphisms and late diabetic complications.
BACKGROUND
Several candidate genes on the short arm of chromosome 6 including the HLA locus, TNF, LTA and AGER could be associated with late diabetic complications. The aim of our study was therefore to explore whether polymorphisms (TNF -308 G-->A, LTA T60N C-->A and AGER -374 T-->A) in these genes alone or together (as haplotypes) increased the risk for diabetic complications.


RESULTS
The studied polymorphisms were genotyped in 742 type 1 and 2957 type 2 diabetic patients as well as in 206 non-diabetic control subjects. The Haploview program was used to analyze putative linkage disequilibrium between studied polymorphisms. The TNF, LTA and AGER polymorphisms were associated with the HLA-DQB1 risk genotypes. The AGER -374 A allele was more common in type 1 diabetic patients with than without diabetic nephropathy (31.2 vs. 28.4%, p = 0.007). In a logistic regression analysis, the LTA but not the AGER polymorphism was associated with diabetic nephropathy (OR 2.55[1.11-5.86], p = 0.03). The AGER -374 A allele was associated with increased risk of sight threatening retinopathy in type 2 diabetic patients (1.65[1.11-2.45], p = 0.01) and also with increased risk for macrovascular disease in type 1 diabetic patients (OR 2.05[1.19-3.54], p = 0.01), but with decreased risk for macrovascular disease in type 2 diabetic patients (OR 0.66[0.49-0.90], p = 0.009). The TNF A allele was associated with increased risk for macrovascular complications in type 2 (OR 1.53 [1.04-2.25], p = 0.03, but not in type 1 diabetic patients.


CONCLUSIONS
The association between diabetic complications and LTA, TNF and AGER polymorphisms is complex, with partly different alleles conferring susceptibility in type 1 and type 2 diabetic patients. We can not exclude the possibility that the genes are part of a large haplotype block that also includes HLA-DQB1 risk genotypes.
Lindholm
Eero
E
Department of Clinical Sciences, University Hospital MAS, Lund University, Lund, Sweden. Eero.Lindholm@med.lu.se
Bakhtadze
Ekaterina
E
Cilio
Corrado
C
Agardh
Elisabet
E
Groop
Leif
L
Agardh
Carl-David
CD
D000368:Aged; D002896:Chromosomes, Human, Pair 6; D048909:Diabetes Complications / Q000235:genetics*; D005260:Female; D005838:Genotype; D006801:Humans; D008233:Lymphotoxin-alpha / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic / Q000235:genetics*; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics*
D008233:Lymphotoxin-alpha; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic; D014409:Tumor Necrosis Factor-alpha