Chromosomal cryptic insertion of the terminal region and its formative mechanism determined by fluorescence in situ hybridization
Tan, Y.; Lu, G.
Chinese Medical Journal 115(7): 1039-1042
2002
ISSN/ISBN: 0366-6999 PMID: 12150739 Document Number: 544807
Objective To determine the karyotype of a cryptic structural abnormality and explore the mechanism of apparent chromosomal terminal deletion. Methods Fluorescence in situ hybridization (FISH) with a whole chromosome 7 painting probe and a 7q subterminal probe (7q36fwdarwqter), prepared by chromosome microdissection technique, was used to analyze a case with a history of spontaneous abortion and 7q terminal deletion detected by conventional G-banding technique. Results The case was a maternal cryptic insertional translocation between chromosome region 1p32 and 7q32fwdarwq35. The region of chromosome 7q36fwdarwqter was not inserted into chromosome 1, and the abnormal chromosome 7 was not a terminal deletion but an interstitial deletion. Conclusions Chromosome insertion of the terminal region retains its telomere, which is consistent with the concept of a three-break rearrangement. Interstitial deletion may be regarded as another mechanism for terminal deletion in the chromosome banding level. Combined with chromosome microdissection, FISH technique could be a powerful diagnostic tool for detecting chromosome structural abnormalities.