Studies on deoxyribonucleic acid polymerase from normal and down’s syndrome skin fibroblasts in vitro

Summary This investigation showed that: (a) hypotonic pH 5.0 extracts of normal and Down’s syndrome fibroblasts cells (DS) exhibit DNase activity which appears to be very similar in nature and extent; (b) DNA polymerase activity was generally increased in DS cells when compared with normal cells; (c) DNA polymerase activity was increased with increased passage age for both normal and DS fibroblasts, but the normal fibroblast was never found to overlap with DS cell activity; and (d) normal cells appear to have a similar DNA polymerase activity at all chronological ages, whereas DS cells exhibit a decrease in activity with increased age of the donor.