Characterization by fluorescence and electron microscopy in situ hybridization of a double Y isochromosome.
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).
Fetni
R
R
Département de Pathologie, Faculté de Médecine, Université de Montréal, Québec, Canada.
Krabchi
K
K
Messier
P E
PE
Richer
C L
CL
Lemieux
N
N
D000328:Adult; D002871:Chromosome Banding; D005260:Female; D005819:Genetic Markers; D006061:Gonadal Dysgenesis, 46,XY / Q000235:genetics*; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D018404:Isochromosomes; D008854:Microscopy, Electron; D014998:Y Chromosome
D005819:Genetic Markers