C(-106)T polymorphism of the aldose reductase gene and the progression rate of diabetic retinopathy.

Purpose: To study the C(-106)T polymorphism in the promoter of the aldose reductase (ALR2) gene: (a) its local prevalence and (b) its modulation of the susceptibility for developing retinopathy.

Methods: DNAs of 96 control subjects and 53 long-standing (duration 17.9+/-5.4 years) type-2 diabetic patients were analyzed by PCR-RFLP with BfaI enzyme. Retinopathy was graded with 2-eye, 7-field fundus color photography. The IMF-HbA1c was the arithmetic mean of all HbA1c's of each patient.

Results: The genotypes in the controls were CC=57 (59.4%), CT=32 (33.3%) and TT=7 (7.3%), with Hardy-Weinberg chi(2)=0.793 (p>0.50). Among 53 diabetics, CC=24 (45.3%), CT=26 (49.0%) and TT=3 (5.7%). The correlation between IMF-HbA1c and retinopathy progression rate was significant on CC (r=0.6102, p=0.0072) but not in CT+TT genotypes (r=0.26, p=0.1811).

Conclusions: In Chilean adults, the frequency of the C(-106)T polymorphism of the ALR2 gene was similar to that reported by others. Type-2 diabetics with the CC genotype were more susceptible for developing retinopathy as a result of chronic hyperglycemia than those with the CT or TT genotype.