The association of uncoupling protein 2 (UCP2) exon 8 insertion/deletion polymorphism and ECG derived QRS duration: A cross-sectional study in an Australian rural population

Background Associations between inherited mitochondrial disease and cardiac conduction have been previously described. However, there are no available studies exploring the mitochondrial uncoupling protein 2 gene (UCP2) insertion/deletion (I/D) polymorphisms interaction on cardiac electrical conduction. Our aim was to determine if ECG-derived QRS duration is associated with UCP2 DD genotype in a cross-sectional Australian aging rural population. Methods A retrospective study design utilizing a rural health diabetic screening clinic data-base containing observational data from September 2011 to September 2014. Inclusion criteria included were having ECG parameters such as QRS duration measures and a DNA sample within the same subject. Genomic DNA was extracted and subjects were genotyped for the 45-bp I/D polymorphism in the 3′-untranslated region of UCP2. Results 281 individuals were available for analysis. On the basis of QRS duration > 140 ms we found an increased percentage of our population with DD homozygotes, compared to ID heterozygotes and II homozygotes (p = 0.047). For other ECG parameters; mean PQ duration, QTc across UCP2 genotypes was not significant (p = NS). QTc using a cut-off > 440 ms in contingency table analysis revealed no significant differences across UCP2 I/D genotypes. Mean QT dispersion (QTd) was paradoxically less in the UCP2 DD genotype compared to UCP2 II subgroup (p = 0.034). Discussion We have demonstrated an association between increasing ECG-derived QRS duration > 140 ms and the UCP2 DD polymorphism. The lack of association with ECG derived QTd and UCP2 DD may suggest that gene-related QRS duration prolongation is independent of cardiac hypertrophy.