Brazilian Journal of Medical and Biological Research
On-line version ISSN 1414-431X
ERRERA, F.I.V. et al. Effect of polymorphisms of the MTHFR and APOE genes on susceptibility to diabetes and severity of diabetic retinopathy in Brazilian patients. Braz J Med Biol Res [online]. 2006, vol.39, n.7, pp. 883-888. ISSN 1414-431X. http://dx.doi.org/10.1590/S0100-879X2006000700005.
Diabetes mellitus (DM) is a highly prevalent complex genetic disorder. There has been a worldwide effort in the identification of susceptibility genes for DM and its complications, and the 5-10-methylenetetrahydrofolate reductase (MTHFR) and apolipoprotein-E (APOE) genes have been considered good candidate susceptibility genes to this condition. The objectives of the present study were to determine if the 677T MTHFR and e2/e3/e4 APOE alleles are risk factors for DM and for severity of diabetic retinopathy (DR). A total of 248 individuals were studied: 107 healthy individuals and 141 diabetic patients (46 with type 1 diabetes and 95 with type 2 diabetes), who also had DR (81 with non-proliferative DR and 60 with proliferative DR). The polymorphisms were analyzed by PCR followed by digestion with restriction enzyme or the single-nucleotide primer extension method. No evidence of association between the 677TT genotype of MTHFR gene and DM [cases: TT = 10/95 (10.6%); controls: TT = 14/107 (13%)] or with severity of DR was observed [cases: TT = 5/60 (8.5%); controls: TT = 9/81 (11.1%); P > 0.05]. We also did not find evidence of an association between APOE alleles and proliferative DR (e2, e3 and e4 in cases: 9, 76, and 15%, and in controls: 5, 88, and 12%, respectively) but the carriers of e2 allele were more frequent among patients with type 2 DM and DR than in controls [cases: 15/95 (15.8%); controls: 7/107 (6.5%); P < 0.05]. Therefore, our results suggest that the e2 allele/APOE might be a risk factor for diabetes in the Brazilian population.
Keywords : APOE; MTHFR; Polymorphisms; Diabetes; Diabetic retinopathy.