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

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

Essay on the nucleoli survey by the alpha- and beta-satellite DNA probes of the acrocentric chromosomes in mitogen-stimulated human lymphocytes

The two constitutive heterochromatin (alpha- and beta-satellite DNA) probes of human acrocentric chromosomes were essayed separately to label the nucleoli in the phytohemagglutinin (PHA)-stimulated human lymphocytes. Fluorescent in situ hybridisation (FISH) results have shown that: a) whole (100 %) signal-nucleoli overlapping was obtained with both heterochromatin probes in maximally activated nuclei (MANs); b) partial overlapping was observed in non activated or slightly activated nuclei; c) random signal-nucleolus overlapping (background level) was found to be similar to 6 % by the NOR-irrelevant euchromatic probe (D5S23); d) Yq-nucleolus association in the MANs was found to be similar to 97 % without the subtraction, of the background level. We concluded that: a) acrocentric alpha- or beta-satellite DNA probes may be used as nucleolar markers only in the MANs and not in slightly activated or non-activated nuclei; b) the distances between rDNA loci and alpha-/beta-satellite DNA on human acrocentrics are short enough to permit their observation on the same nucleolus. (C) 2000 Editions scientifiques et medicales Elsevier SAS

Female-to-male transsexual with 47,XXX karyotype

Background: There are few reports describing chromosomal abnormalities in transexuals. In rare cases, transsexualism and sexual chromosomal multiplicity coexist. Six cases of male-to-female transsexuals with 47,XYY chromosomal pattern have been previously reported, We have not encountered any female transsexual cases with 47,XXX karyotype in the literature

A case with Waardenburg syndrome presenting with two separate translocations - one reciprocal and one complex

A 2-month-old Turkish male with Waardenburg syndrome who has two de novo translocations is described. The translocations are a reciprocal translocation between chromosomes 1 and 8, and a more complex translocation involving chromosomes 4 and 7. Clin Dysmorphol 10: 65-66 (C) 2001 Lippincott Williams & Wilkins