Epistatic effects of ACE I/D and AGT gene variants on left ventricular mass in hypertensive patients: The HyperGEN Study

Identifying predictors of left ventricular hypertrophy has been an active study topic because of its association with cardiovascular morbidity and mortality. We examined the epistatic effect (gene-gene interaction) of two genes (ACE I/D; AGT -6G-A, M235T, -20A-C) in the renin-angiotension system (RAS) on left ventricular mass (LVM) among hypertensive participants in the HyperGEN study. Included were 2156 participants aged 20–87 years (60% women, 63% African American). We employed mixed linear regression models to assess main effects of four genetic variants on echocardigraphically determined LVM (indexed for height), and ACE-by-AGT epistatic effects. There was evidence that AGT -6G-A was associated with LVM among white participants: Adjusted mean LVM (g/m(2.7)) increased with ‘G’ allele copy number (‘AA’:41.2, ‘AG’:42.3, ‘GG’:44.0; p=0.03). There was also evidence of an ACE I/D-by-AGT -20A-C epistatic effect among white participants (interaction p=0.03): Among ACE ‘DD’ participants, AGT -20A-C ‘C’ allele carriers had lower mean LVM than ‘AA’ homozygotes (‘DD/CC’:39.2, ‘DD/AC’:39.9, ‘DD/AA’:43.9), with no similar significant effect among ACE ‘I’ allele carriers (‘ID/CC’:47.2, ‘ID/AC’:43.4, ‘ID/AA’:42.6; ‘II/CC’: NA, ‘II/AC’:41.3, ‘II/AA’:43.1). These findings indicate that RAS variants in at least two genes may interact to modulate LVM.