A variant of the IGF-I gene is associated with blood pressure but not with left heart dimensions at the age of 2 years: the Generation R Study

Abstract

A common variant of the IGF-I gene has been shown to be associated with cardiovascular disease in adulthood. The objective of this study was to examine whether this variant of the IGF-I gene is associated with blood pressure and left heart dimensions in early childhood. This study was embedded in the Generation R Study, a population-based prospective cohort study from foetal life onwards. IGF-I promoter region was genotyped in DNA obtained from cord blood. Blood pressure (systolic and diastolic) and echocardiography (left ventricular mass, left atrial diameter and aortic root diameter) measurements were performed at the age of 2 years. Analyses were performed in 538 subjects. Eight alleles of the IGF-I promoter region were identified. In total, 43% of the subjects were homozygous for the 192 bp allele (wild type), 46% were heterozygous and 11% were non-carriers. Significantly lower systolic and diastolic blood pressures were found in non-carrier subjects (difference compared with homozygous subjects: -4.4 (95% confidence interval (CI) -7.8 to -1.1) mmHg and -3.5 (95% CI: -6.9 to -0.1) mm respectively). No significant differences were found for left heart dimensions at the age of 2 years. No association was found when we used a previously proposed alternative classification of the IGF-I gene. The variant type of the IGF-I promoter region is associated with lower blood pressure but not with left heart dimensions at the age of 2 years. Follow-up studies are needed to examine whether these differences persist in later life.