Early origins of heart disease: Low birth weight and the role of the insulin-like growth factor system in cardiac hypertrophy

1. Epidemiological studies indicate that poor growth before birth is associated with left ventricular hypertrophy and an increased risk of death from heart disease later in life. 2. In fetal life, the insulin-like growth factor (IGF) system has been implicated in physiological growth of the heart, whereas in postnatal life IGFs can be involved in both physiological and pathological cardiac hypertrophy. 3. A reduction in substrate supply in fetal life, resulting in chronic hypoxaemia and intrauterine growth restriction, results in increased cardiac IGF-1R, IGF-2 and IGF-2R gene expression; and there is also evidence for a role of the IGF-2 receptor in the ensuing cardiac hypertrophy. 4. The persistent high level of cardiac IGF-2R gene expression from fetal to postnatal life may be due to epigenetic changes in key cardiac hypertrophy regulatory pathways.