Fluorescent in situ hybridization utilization for high-risk prenatal diagnosis: a trade-off among speed, expense, and inherent limitations of chromosome-specific probes
Evans, M.I.; Ebrahim, S.A.; Berry, S.M.; Holzgreve, W.; Isada, N.B.; Quintero, R.A.; Johnson, M.P.
American Journal of Obstetrics and Gynecology 171(4): 1055-1057
ISSN/ISBN: 0002-9378 PMID: 7943069 DOI: 10.1016/0002-9378(94)90034-5
OBJECTIVE: The development of fluorescent in situ hybridization chromosome-specific probes has allowed the use of new fetal tissue collection techniques, such as fetal cells in maternal blood and coelocentesis-both of which, with current techniques, cannot generate complete karyotypes. We evaluated chromosome-specific probes for additional potential limitations in the setting of a high-risk prenatal diagnosis center. STUDY DESIGN: The last 24 months of fetal karyotypes from our prenatal cytogenetics laboratory were analyzed for those abnormalities that should be detectable by chromosome-specific probes and those that would likely be missed. RESULTS: In 6006 karyotypes 207 (3.4%) abnormalities were found, of which 104 were common trisomies, 12 triploidies, and 19 monosomies that would have been detected with current probe combinations (13, 18, 21, X, and Y) (135/207, 65.2%). Seventy-two abnormalities (35%) represented other trisomies (16/207, 7.7% for 9, 12, 15, 16) and rearrangements (inversions, translocation markers were 56/207, 27.1%), which would have been missed. CONCLUSIONS: Use of current fluorescent in situ hybridization chromosome-specific probes protocols would have detected only 65% of chromosome abnormalities in our high-risk population. Incomplete ascertainment must be weighed against the cost and speed of fluorescent in situ hybridization chromosome-specific probes when comparing it with traditional karyotyping. Although this new technique may prove useful in low-risk screening programs (fetal cells in maternal blood), its current use in high-risk populations should be questioned until its sensitivity is expanded to identify more subtle and less common chromosomal abnormalities.