Identification of 14 rare marker chromosomes and derivatives by spectral karyotyping in prenatal and postnatal diagnosis

Abstract

Extra structurally abnormal chromosomes (ESACs) and cryptic rearrangements are often associated with mental retardation and phenotypic abnormalities. In some cases their characterisation, using standard cytogenetic techniques and fluorescence in situ hybridization (FISH), is difficult and time consuming, where a fast and accurate identification is essential, especially when such chromosomal aberrations are found in prenatal diagnosis. A recent molecular technique, spectral karyotyping (SKY), based on the spectral signature of 24 chromosome-specific painting probes labelled with different combinations of five fluorochromes, allows the simultaneous visualisation of all human chromosomes in different colours. We used SKY analysis on 14 cases with rare ESACs or cryptic unbalanced rearrangements found at pre- or postnatal diagnosis. SKY analysis permitted the classification of chromosome rearrangements in all 14 cases analysed in combination with FISH analysis.

Chromosome abnormalities without phenotypic consequences

“…Therefore more sophisticated approaches have been developed. The application of micro-FISH (Anderlid et al 2001;Engelen et al 2003;Trimborn et al 2005) and multicolor karyotyping technologies, such as multiplex-FISH (M-FISH), including centromere-specific multicolor FISH (cenM-FISH; Nietzel et al 2001) or spectral karyotyping (SKY) (Guanciali-Franchi et al 2004) in analysis of marker chromosomes, was demonstrated in the literature. Taking into account that approximately 80% of all SMCs derive from acrocentric chromosomes, Langer et al (2001) described a new strategy for their rapid and detailed identification.…”

Spectral karyotyping of human, mouse, rat and ape chromosomes – applications for genetic diagnostics and research

“…SKY analysis permitted the classification of marker chromosomes and chromosome rearrangements and the results were confirmed by using locus/gene-specific probes with FISH analysis (Haddad et al, 1998;Huang et al, 1998;Ning et al, 1999;Yaron et al, 2003;Guanciali-Franchi et al, 2004;Tabet et al, 2004). However, in two cases of small bisatellited chromosomes, SKY was noncontributory (Yaron et al, 2003).…”

A de novo Complex Chromosome Rearrangement Involving Chromosomes 2, 3, 5, 9 and 11 Detected Prenatally and Studied Postnatally by Conventional Cytogenetics and Molecular Cytogenetic Analyses

“…To our knowledge, prenatally ascertained de novo apparently balanced complex and multiple chromosomal rearrangements have been reported in 19 cases [3,9,15,16] . Here, we describe a new case of a de novo CCR de- tected prenatally by conventional cytogenetics and fluorescence in situ hybridization (FISH).…”

“…Accurate identification of CCRs is a challenge to cytogeneticists, especially when they are found in prenatal diagnosis posing problems in counseling couples [3,9] . The application of molecular cytogenetics has greatly improved the accuracy of cytogenetic diagnosis and uncovered a number of cryptic aberrations in cases previously studied by conventional cytogenetics [8,[10][11][12][13][14] .…”

“…CCRs of type II are rare; most are de novo events [4,5] . Individuals with congenital CCR have been ascertained because of mental retardation, multiple congenital anomalies, recurrent pregnancy loss, or infertility, even in the cytogenetic balanced form [6][7][8][9] .…”