[Detection of aneuploidies using in situ hybridization in cells of the oral mucosa]. / Detección de aneuploidías por hibridación in situ en células de mucosa oral.

Aneuploidies have been traditionally diagnosed by chromosome analysis, however this method may be difficult to perform in certain cellular types or in severely ill patients. With the fluorescence in situ hybridization (FISH) technique it is possible to identify the number of specific chromosomes in interphase cells. In the present study we analyzed exfoliated epithelial cells from the oral mucosa of 15 patients with trisomy 21, and in six patients with mosaicism; five normal subjects were included for comparison. To allow the probe to reach its target DNA we first treated the keratin-surrounded membrane with pepsin during 20 minutes. In the 15 cases of trisomy 21, the cells showed five fluorescent signals indicating the presence of three chromosomes 21 and two 13, while the normal subjects showed four signals. In one girl with Turner syndrome and a karyotype 46,X+mar, the FISH analysis in 1000 cells revealed that the marker derived from chromosome X and there was a mosaicism 45,X/46,X,r(X). In the other patients with mosaicisms, we observed variations in the proportions of cells but the differences were not significant. In conclusion, interphase FISH on buccal cells showed to be a rapid, effective and non-invasive method for the diagnosis of chromosome aberrations, particularly when the cytogenetic study on lymphocytes is difficult to perform.