Condensed chromatin surface and NORs surface enhancement in mitogen-stimulated lymphocytes of Down syndrome patients

Demirtaş H., Imamoglu N. N., Donmez H., Cucer N., Yilmaz A., Candemir Z.

ANNALES DE GENETIQUE, vol.44, no.2, pp.77-82, 2001 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 44 Issue: 2
  • Publication Date: 2001
  • Doi Number: 10.1016/s0003-3995(01)01041-3
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.77-82
  • Erciyes University Affiliated: Yes


Mitogen-stimulated lymphocytes of 20 Down syndrome (DS) patients with regular trisomy 21 contain more condensed chromatin surface (11.28 +/- 2.64% of the total nuclear surface: mean SD) and more nucleolus organiser regions surface (13.21 +/- 3.45 %) than that of 12 healthy controls: (8.84 +/- 2.23 and 9.12 +/- 2.33 %, reciprocally). The source of this peculiarity has been investigated. A computer program was designed for the planimetric measurement of the condensed chromatin surface (CCs)/ total nuclear surface(TNs) and the nucleolus organiser regions surface (NORss) /TNs proportions in interphase nuclei. CCs/TNs and NORss/TNs of 100 maximally activated nuclei (MANS) were measured for each patient and control case. The difference was found highly significant (P < 0.01). Nuclei with a diameter of greater than or equal to 17 mum measured on the slide (in flattened state) were considered as maximally activated nuclei (MANS). NORss/TNs enhancement and fluorescent in situ hybridisation (FISH) studies in MANS of DS patients indicate that this phenomenon is due to the over-expression (or lack of downregulative mechanism) of NORs (rDNA) to some extent, including the NOR of the supernumerary chromosome 21. No statistical difference was observed between 12 healthy controls and 5 Robertsonian translocation type of DS Patients (where the two involved NORs are missing) when the two parameters were considered. (C) 2001 Editions scientifiques et medicales Elsevier SAS.