Nuclear DNA content of the normal and hypertrophied myocardium in the pediatric age group

The DNA content of individual muscle cell nuclei in normal and hypertrophied children's hearts was studied by microspectrophotometric measurements of Feulgen-stained sections. Normal newborn myocardium was found to have a diploid DNA distribution. In four patients (ranging in age from 2 years, 10 months to 12 years) with cardiac hypertrophy, a polyploid distribution of DNA values was found. This finding is consistent with the findings in hypertrophied adult hearts. Polyploidization in both adults and children may occur in response to the demands of higher cellular activity in the heart. The mechanism by which increased functional requirements induce polyploidy in the human myocardium is unknown.