Relationship between polymorphisms 804C/A and 252A/G of lymphotoxin-alpha gene and -308G/A of tumor necrosis factor alpha gene and diabetic retinopathy in Japanese patients with type 2 diabetes mellitus.

To clarify whether polymorphisms of the lymphotoxin-alpha (LTA) gene and tumor necrosis factor alpha (TNF-alpha) gene were related to diabetic retinopathy (DR), we performed a case-control study in 251 Japanese patients with type 2 diabetes mellitus participating in a multicenter research protocol. Genetic analyses were performed by using a fluorescent allele-specific DNA primer assay system. Diabetic retinopathy was diagnosed in a masked manner by an independent ophthalmologist using fundus photographs and was classified as nondiabetic retinopathy (NDR), nonproliferative retinopathy (NPDR), and proliferative retinopathy (PDR). The results showed that the genotype frequencies of 804C/A in exon 3 and 252A/G in intron 1 of the LTA gene were not significantly different among patients with NDR, NPDR, and PDR. A allelic frequency of the TNF-alpha gene (-302A/G in promoter) was also identical among NDR, NPDR, and PDR groups. Multivariate logistic regression analyses showed that significant associations with DR were glycosylated hemoglobin level and diabetes duration, but not polymorphisms of the LTA gene or TNF-alpha gene. In conclusion, the present study showed no association between polymorphisms 804C/A and 252A/G of the LTA gene and -302A/G of the TNF-alpha gene and DR in Japanese type 2 diabetic patients.