Aim: To compare the frequencies of the G1888A variant in the mitochondrial 16S rRNA gene between patients with Type 2 diabetes and non-diabetic control subjects from southern Brazil.
Methods: We analysed 520 Type 2 diabetic patients (389 Caucasian- and 131 African-Brazilians) and 530 control subjects (400 Caucasian- and 130 African-Brazilians). DNA samples were amplified by polymerase chain reaction and digested with the RsaI enzyme. Variant frequency in patients and control subjects was compared using chi2 test, Fisher's exact test or odds ratio test. We also investigated the frequency of the G1888A variant in a subgroup of the patients with a maternal history of Type 2 diabetes plus two or more features of maternally inherited diabetes and deafness.
Results: The 1888A allele does not seem to be associated with Type 2 diabetes in African-Brazilians (frequency of 3.8% in patients and 0.8% in control subjects; PFisher=0.213). However, in Caucasian-Brazilians, the 1888A allele was significantly associated with diabetes (12.3% in patients vs. 3.5% in control subjects; OR=3.881; 95% CI 2.106-7.164; P<0.001) and also with higher levels of insulin resistance. The majority of the patients carrying the 1888A allele did not have clinical features of maternally inherited diabetes and deafness.
Conclusion: The present study indicates the association of the mitochondrial G1888A variant with Type 2 diabetes and insulin resistance in Caucasian-Brazilian patients from southern Brazil. However, further studies are required to confirm its effects on mitochondrial function and the role of these effects on the pathogenesis of Type 2 diabetes.