Yueqiu Tan1, Guangxiu Lu. 1. Human Reproductive Engineering Laboratory, Xiangya School of Medicine, Central South University, Changsha 410078, China.
Abstract
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 (7q36-->qter), 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 7q32-->q35. The region of chromosome 7q36-->qter was not inserted in to 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.
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 (7q36-->qter), 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 7q32-->q35. The region of chromosome 7q36-->qter was not inserted in to 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.