Effect of polymorphisms of the MTHFR and APOE genes on susceptibility to diabetes and severity of diabetic retinopathy in Brazilian patients.
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 epsilon2/epsilon3/epsilon4 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 (epsilon2, epsilon3 and epsilon4 in cases: 9, 76, and 15%, and in controls: 5, 88, and 12%, respectively) but the carriers of epsilon2 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 epsilon2 allele/APOE might be a risk factor for diabetes in the Brazilian population.
Errera
F I V
FI
Centro de Estudos do Genoma Humano, Instituto de Biociências, USP, São Paulo, SP, Brasil.
Silva
M E R
ME
Yeh
E
E
Maranduba
C M C
CM
Folco
B
B
Takahashi
W
W
Pereira
A C
AC
Krieger
J E
JE
Passos-Bueno
M R
MR
D000368:Aged; D000483:Alleles; D001057:Apolipoproteins E / Q000235:genetics*; D016022:Case-Control Studies; D003922:Diabetes Mellitus, Type 1 / Q000235:genetics*; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics*; D003930:Diabetic Retinopathy / Q000235:genetics*; D005260:Female; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D008297:Male; D042965:Methylenetetrahydrofolate Reductase (NADPH2) / Q000235:genetics*; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D012307:Risk Factors; D012720:Severity of Illness Index
D001057:Apolipoproteins E; D042965:Methylenetetrahydrofolate Reductase (NADPH2)