Rapid detection of chromosome aneuploidies in fetal blood and chorionic villi by fluorescence in situ hybridisation

Abstract

Objective Evaluation of fluorescence in situ hybridisation in the detection of numerical aberrations involving chromosomes X, Y, 13, 18 and 21. Setting Harris Birthright Research Centre for Fetal Medicine. Subjects and methods Chorionic villi (n= 45) or fetal blood (n= 34) were obtained from 79 pregnancies undergoing fetal karyotyping at 10 to 39 weeks of gestation because of ultrasonographic markers of fetal chromosomal abnormality. Karyotyping was performed by both traditional cytogenetics and fluorescence in situ hybridisation, using commercially available kits which utilise a heterochromatic Y probe and the alpha satellite repeat probes for chromosomes X, 18, and 13/21. The frequency distributions of the number of signals obtained by fluorescence in situ hybridisation in the chromosomally normal and abnormal fetuses were compared. Results Traditional cytogenetic analysis demonstrated that the fetal karyotype was normal in 47 cases and abnormal in 32 (including 24 with trisomies 21, 18 or 13, three with triploidy, one with Turners syndrome and four with translocations, deletions or mosaicism). With fluorescence in situ hybridisation it was possible to obtain accurate diagnosis of trisomy 18, Turners or triploidy within six hours of sampling; signal distributions with these chromosomal abnormalities were very different from those of normals. However, for trisomies 21 and 13 there was an overlap in values with those from normals. Conclusions In detection of fetal numerical chromosomal abnormalities the use of the combined 13/21 probe cannot provide sufficiently accurate results to justify abandonment of traditional cytogenetics in favour of fluorescence in situ hybridisation.

Correlation of prenatal clinical findings with those observed in fetal autopsies: pathological approach

“…In utero recognition is observer and facility dependent as shown by the high number of unidenti®ed cases in our series. The role of interphase cytogenetic examination in perinatal cytogenetic diagnosis has been extensively studied (Pandya et al, 1994;Pergament et al, 2000). It can not replace metaphase examination, but it is a good alternative for the fetopathologist and can be used on formalin-®xed cells, even after paraf®n embedding (Cobben et al, 1994).…”

Review article

“…The combination of these techniques could yield a near ideal test for fetal aneuploidies. However, further work is needed before the sensitivity and specificity are sufficient for a routine screening program [112].…”

Identification and quantitation of human chromosomes by primedin situ synthesis

“…When the material to be analysed can be cultured to produce metaphase chromosomes, in situ hybridization probes derived from complete chromosomal DNA libraries have been extremely valuable (Bienz et aI. 1993;Pandya et al 1994). A recent publication claims to be able to analyse the complete human karyotype (23 chromosome pairs) in a single step by labelling the individual chromosome probes with differing ratios of haptens, and using a sophisticated fluorescence microscope and computer image analysis system to distinguish the different labels (Speicher et al 1996).…”