Analysis of marker or complex chromosomal rearrangements present in pre‐ and post‐natal karyotypes utilizing a combination of G‐banding, spectral karyotyping and fluorescence in situ hybridization

Abstract

The significance of complex chromosomal rearrangements presents a diagnostic dilemma. In the past, the use of G-banding coupled with fluorescence in situ hybridization (FISH) has been the standard approach. The recent development of spectral karyotyping (SKY) and multicolor FISH (M-FISH) has resulted in an increased accuracy of identification of marker or other complex chromosomal rearrangements. However, owing to the additional cost and time associated with SKY or M-FISH, and the restricted availability of such imaging facilities in many centers, it is not feasible to perform these procedures routinely on every sample. In addition, the identification of an aberration by SKY or M-FISH will often require confirmation by FISH. A practical approach is needed to take advantage of the complementary strengths of each method. In our center we utilize an algorithm that dictates the use of routine G-banding for the initial preliminary evaluation of a patient, followed by SKY characterization if marker chromosomes or complex translocations are detected by the G-banding analysis. According to this algorithm, FISH is used to verify the results once the origin of the abnormal chromosome has been determined by SKY. To demonstrate the effectiveness of this algorithm, we have analyzed both amniocyte and lymphocyte slides, using a combination of G-banding, SKY, and FISH. Our results confirm that an algorithm which selectively uses SKY or M-FISH will provide an efficient and improved method for pre- and post-natal chromosomal analysis.

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

“…A very rare de novo Y-autosome translocation consisting of chromosomal regions on chromosomes 5 and Y was found in association with a partial duplication of Yq in a male newborn patient with Cri-du-chat syndrome (karyotype 46,XY.ish der(5)t(Y; 5)(q11.2;p15.3)(SKY+,Xq/YqTEL+,5pTEL-)) . Other studies were performed with comparable results Phelan et al, 1998;Peschka et al, 1999;Heng et al, 2003). Surprisingly, a complex chromosomal rearrangement consisting of 16 fragments was reported in a boy with moderate mental retardation and very short stature.…”

Supernumerary marker chromosome 5 diagnosed by M-FISH in a child with congenital heart defect and unusual face

“…Liehr et al (2006) also report a female diagnosed prenatally with a very small marker (5p) and with mental retardation, VSD, facial dysmorphism and other clinical problems ( Table 1 ). Heng et al (2003) reported a case where SKY clarified an extra chromosomal material as being min(5) with no other available data. Kocarek et al (2004) also reported a developmentally abnormal case with 47 chromosomes and an extra sSMC, characterized with FISH as derived from chromosome 5 (abstract in English, article in Czech).…”

Mitotic Cell Death by Chromosome Fragmentation

“…SKY was done on mitotic spreads as described (25,26). Briefly, cytogenetic slides were denatured and hybridized with human painting probes.…”