Fluorescent in situ hybridization (FISH) with a 21q11-specific probe (CB21c1) consisting of three non-overlapping cosmids has been applied to interphase amniocytes of pregnancies at increased risk for fetal aneuploidy (N = 78) and to interphase lymphocytes, cultured and uncultured, of patients referred for Down syndrome (N = 19 and 28, respectively). In the uncultured amniocytes, six chromosome aberrations were detected: three cases of trisomy 21, a triploidy, a de novo 46,XX,t(21q21q), and a mosaic 46,XY/47,XY,+dic(21)(q11)/48,XY,+dic(21)(q11), +del(21)(q11). In 15 cultured and 20 uncultured blood samples, FISH correctly diagnosed trisomy 21 (full or mosaic) at the interphase level, which was confirmed in all cases by subsequent karyotyping. Because of specific and strong signals in interphase nuclei, CB21c1 appears to be a useful tool for the rapid detection of chromosome 21 abnormalities.

21q11 cosmids, Interphase cytogenetics, Mosaic trisomy 21, Translocation (21q21q), Uncultured amniocytes
dx.doi.org/10.1002/pd.1970150805, hdl.handle.net/1765/68350
Prenatal Diagnosis
Department of Clinical Genetics

Van Opstal, A.R.M, van Hmel, J.O, Eussen, H.J.F.M.M, van der Heide, A, van den Berg, C.D.F, in't Veld, P.A, & Los, F.J. (1995). A chromosome 21-specific cosmid cocktail for the detection of chromosome 21 aberrations in interphase nuclei. Prenatal Diagnosis, 15(8), 705–711. doi:10.1002/pd.1970150805