The clinical application of spectral karyotyping (SKY) in the analysis of prenatally diagnosed extra structurally abnormal chromosomes (ESACs).
OBJECTIVE
The prenatal detection of de novo extra structurally abnormal chromosomes (ESACs) presents a challenge because the associated risk for congenital anomaly ranges from 100% to practically none, depending on the chromosomal origin. Despite the use of standard cytogenetic techniques and even fluorescence in situ hybridization (FISH), the origin of some ESACs often remains elusive. Spectral karyotyping (SKY) is a molecular cytogenetic technique based on the simultaneous analysis of all chromosomes using a unique probe mix that allows the rapid identification of all chromosomes in 24 colors. The purpose of this study was to evaluate the use of SKY in the characterization of prenatally diagnosed de novo ESACs.


METHODS
This series includes five cases of de novo ESACs detected prenatally in routine amniocentesis samples performed for advanced maternal age. Cases of inherited ESACs or ESACs defined by standard cytogenetic techniques were excluded.


RESULTS
SKY analysis yielded valuable information, particularly in cases of nonsatellited ESACs: a der(18) and a ring(Y). In a case of a unisatellited der(15), SKY corroborated data obtained by standard cytogenetic techniques and FISH. Finally, in two cases of small bisatellited chromosomes, SKY was noncontributory.


CONCLUSIONS
While SKY may be a valuable tool in some cases, especially nonsatellited and ring ESACs, it does have limitations and should be used judiciously in conjunction with other cytogenetic techniques.
Yaron
Yuval
Y
Prenatal Diagnosis Unit & Genetic Institute, Sourasky Medical Center, Tel Aviv, Israel. yyaron@tasmc.health.gov.il
Carmon
Erez
E
Goldstein
Myriam
M
Voskoboinik
Nadia
N
Ochshorn
Yifat
Y
Gelman-Kohan
Zully
Z
Orr-Urtreger
Avi
A
D000328:Adult; D000649:Amniocentesis; D002869:Chromosome Aberrations; D025063:Chromosome Disorders / Q000175:diagnosis* / Q000235:genetics; D003657:Decision Making; D003661:Decision Support Techniques; D005260:Female; D005817:Genetic Counseling; D005819:Genetic Markers; D006801:Humans; D008423:Maternal Age; D008875:Middle Aged; D011247:Pregnancy; D018566:Pregnancy, High-Risk; D032681:Spectral Karyotyping
D005819:Genetic Markers