Unbalanced mosaic karyotypes with different structural abnormalities involving a common chromosome region: Report of two cases

Abstract

We report on 2 cases with different de novo unbalanced mosaic karyotypes in which each cell line had a different structural abnormality involving a common chromosome region: 46,XX,del(11)(q23.3)/46,XX.-11, + der(11)t(11;?)(q23.3;?) and 46,X,idic(Xq)/46,X,idic(Xq),-12, + der(12)t(X;12)(p11.2;p13.3). Molecular-cytogenetic analysis confirmed the origin of the derivative 12 chromosome in the latter. We present a literature review of reports with mosaic cell lines of structural chromosome abnormalities that share the same chromosome breakpoint.

Incidence and Significance of Chromosome Mosaicism Involving an Autosomal Structural Abnormality Diagnosed Prenatally Through Amniocentesis: A Collaborative Study

“…This possibility is especially entertainable in the two cases with de1(10)(q23) (one of which had a familial fragile site at 10q23) and in one case each of del(2)(qll) and de1(2)(q3 1). There are four reports of liveborns mosaic for deletions which involve the same bands as known fragile sites (1Oq23- Maltby and Higgins, 1987;1 lq23-Voullaire et al, 1987;and Pettenati et al, 1993). Familial fragile sites were noted in the 10q23 study and in the 1 lq23 study of Voullaire et al (1987).…”

Unique mosaicism of structural chromosomal rearrangement: Is chromosome 18 preferentially involved?

“…We have found 14 published cases involving chromosome 18; this chromosome appears to be most frequently involved in these structural rearrangements (Table II). As far as we know, only a few articles describe cases involving other chromosomes (chromosome 2 [Wyandt et al, 1982], chromosomes 2 and 14 [Engelen et al, 2000], chromosome 4 [Pescia et al, 1982; Smeets et al, 1998; Doco‐Fenzy et al, 1999; Schinzel, 2000; Syrrou et al, 2001], chromosome 5 [Perfumo et al, 2000], chromosome 8 [Van Balcom et al, 1992], chromosome 9 [Leung and Rudd, 1988], chromosome 11 [Pettenati et al, 1993; Tharapel et al, 1999], chromosome 13 [Fryns et al, 1979; Jalal et al, 1990; Duckett et al, 1992], chromosome 17 [Scriven and Docherty, 1992], and X chromosome [Pettenati et al, 1993]). The general “gene poverty” of chromosome 18 [International Human Genome Sequencing Consortium, 2001] could explain why this chromosome appears to be most frequently involved in structural rearrangement mosaicisms that are compatible with life.…”

“…There are few descriptions of mosaicisms of two unbalanced cell lines, and they mostly concern intra chromosomal duplication/deletion for the same chromosomal region. Inter chromosomal reciprocal translocations coexisting as two or more different (unbalanced) cell lines are even less frequent [Scriven and Docherty, 1992; Pettenati et al, 1993; Smeets et al, 1998; Doco‐Fenzy et al, 1999; Schinzel, 2000].…”

Incontinentia pigmenti versus hypomelanosis of Ito: The whys and wherefores of a confusing issue

“…In a recent issue of the AJMG, Jewett et al [1997] reconsider a case of a mosaic cell line showing a de novo unbalanced X;autosome translocation present in a girl with multiple developmental defects including mental retardation [Pettenati et al, 1993]. Because of a recently recognized interruption of the Xp11.2 region, and in view of the additional finding of swirling areas of alternating hyper-and hypopigmentation, they conclude that this case represents another confirmation of the association of incontinentia pigmenti with Xp11.…”