| Abstrakt: |
In peripheral blood lymphocytes taken from 7 patients with Down syndrome (DS) and 2 normal donors, using DNA fiber autoradiography, we estimated the rate of DNA-chain growth, which depends oil the number of simultaneously replicating adjacent replicon clusters, but not on the rate of fork movement. No difference was found in the rate of fork movement in these cells. 6 of 7 DS patients showed a significant reduction in the rate of DNA-chain growth as compared to that in normal control. Thus, a new molecular defect in DS lymphocytes has ben first revealed. Besides, new arguments have been provided in favour of genetic heterogeneity of this genetic disorder belonging to premature ageing diseases. Relation of molecular DNA replication defects with ageing is discussed. |
