First prenatally detected small supernumerary neocentromeric derivative chromosome 13 resulting in a non-mosaic partial tetrasomy 13q

Abstract

Neocentromeres are functional centromeres located in non-centromeric euchromatic regions of chromosomes. The formation of neocentromeres results in conferring mitotic stability to chromosome fragments that do not contain centromeric alpha satellite DNA. We present a report of a prenatal diagnosis referred to cytogenetic studies due to ultrasound malformations such as large cisterna magna, no renal differentiation, hypotelorism and ventriculomegaly. Cytogenetic analysis of GTG-banded chromosomes from amniotic fluid cells and fetal blood cells revealed a de novo small supernumerary marker chromosome. Molecular cytogenetic studies using fluorescence in situ hybridization and comparative genomic hybridization showed this marker to be an inverted duplication of the distal portion of chromosome 13q which did not contain detectable alpha satellite DNA. The neocentromeric constriction was located at band 13q31. The presence of a functional neocentromere on this marker chromosome was confirmed by immunofluorescence with antibodies to centromere protein-C. The anatomopathologic study revealed a female fetus with facial dysmorphisms, low set ears and renal dysplasia. Ten small supernumerary neocentromeric chromosomes originating from the distal region of chromosome 13q have been reported to date. There are only three additional cases described with the location of the neocentromere in band 13q31. This is the first reported case detected prenatally.

Tetrasomy 13q31.1qter due to an inverted duplicated neocentric marker chromosome in a fetus with multiple malformations

“…In these neocentric sSMC 13q, four distinct regions have been found to contain neocentromeres: 13q21 (five cases) [Tohma et al, 1998; Morrissette et al, 2001; Li et al, 2002; Knegt et al, 2003; Dhar et al, 2009], 13q31 (five cases) [Tohma et al, 1998; Barwell et al, 2004; Tonnies et al, 2006; Liehr et al, 2007; Mascarenhas et al, 2008], 13q31/32 (one case) [Amor et al, 2005] and 13q32 (seven cases) [Depinet et al, 1997; Lozzio et al, 1997; Warburton et al, 1997; Govaerts et al, 1999; Rivera et al, 1999; Li et al, 2002] (Table I).…”

Neocentromeres and epigenetically inherited features of centromeres

“…Marker chromosomes are abnormal chromosomes formed by rearrangements or amplifications of specific genomic regions. Phenotypes associated with marker chromosomes stabilized by neocentromeres include: facial dysmorphisms, renal defects, short stature, and developmental delays (Mascarenhas et al, 2008, Burnside et al, 2011). Prenatal identification of neocentric marker chromosomes can be achieved by cytogenetic analysis of chromosomes from amniotic fluid and fetal blood cells (Mascarenhas et al, 2008).…”

Characterizing Small Supernumerary Marker Chromosomes with Combination of Multiple Techniques

“…More than 10 neocentromeric sSMCs originating from the distal region of chromosome 13q were summarized by some studies Mascarenhas et al, 2008;Ewers et al, 2010], with one of them, which showed a similar duplicated size as the sSMC in case 12, identified prenatally.…”