[Molecular cytogenetic detection of minute chromosomal structural abnormality on the chromosomal terminal regions].

In order to identify those easily overlooked minute chromosomal structural abnormality on the chromosomal regions, and to provide a valuable guidance for pregnancy, fluorescence in situ hybridization (FISH) technique by whole chromosome 7 painting probe, Xq probe and subterminal probe of 7q36-->qter was performed to analyze two cases. Case 1 had a history of recurrence spontaneous abotion and with an uncertain minute translocation on the chromosomal terminal regions. Case 2 was a premature ovarian failure patient with a balanced translocation between chromosome X and chromosome 7 by G banding. The results showed that case 1 was a cryptic minute translocation on the chromosomal terminal regions, and the breakpoint of case 2 was accurately determined, that is, the breakpoint was not on 7q36 but on 7qter. Therefore FISH technique with whole chromosome painting probe and subterminal probe could be used to diagnose the minute chromosomal structural abnormality on the chromosomal regions. It could be used widely in the clinical genetics and was an effective tool for genetic counseling and reproductive guidance.