Characterization by fluorescence and electron microscopy in situ hybridization of a double Y isochromosome

✍ Scribed by Fetni, Raouf; Krabchi, Kada; Messier, Paul-Emil; Richer, Claude-Lise; Lemieux, Nicole

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 24 KB
• Volume: 63
• Category: Article
• ISSN: 0148-7299
• DOI: 10.1002/(sici)1096-8628(19960614)63:3<454::aid-ajmg7>3.0.co;2-r

✦ Synopsis

A patient with mixed gonadal dysgenesis and Y isochromosomes i(Y) is described. Lymphocyte cultures from peripheral blood contained a high proportion of 45,X cells and several other cell lines with two different marker chromosomes (mars). These markers had either a monocentric (mar1) or a dicentric appearance (mar2). Following high-resolution GTG, RBG, QFQ, and CBG bandings, five cell lines were identified; 45,X/46,X,+mar1/46,X,+mar2/47,X,+mar1x2/47,X,+mar2x 2. The percentages were 66/6/26/1/1%, respectively. Chromosome banding analyses were insufficient for characterization of the markers. In situ hybridization of specific probes for the Y centromere and its short arm showed, both in fluorescence and electron microscopy (EM), two different Y rearrangements. Mar1 is an isochromosome for the short arm i(Yp) and mar2 is a dicentric which was shown by EM to be a double isochromosome Yp, inv dup i(Yp). The breakpoint producing mar1 is within the centromere and the one producing mar2 is within one of the short arms of the Y isochromosome. The findings of different cell populations in peripheral blood lymphocytes indicate the postzygotic instability of this i(Yp).