Cytogenetic analyses of culture failures by comparative genomic hybridisation (CGH)–Re-evaluation of chromosome aberration rates in early spontaneous abortions

Abstract

Comparative genomic hybridisation (CGH) represents an alternative molecular-cytogenetic technique capable of detecting chromosomal imbalances by reverse fluorescence in situ hybridisation. As the technique uses genomic DNA for assessment it does not rely on metaphase chromosomes in the test material and thus circumvents technical problems associated with tissue culturing. In the present study, we applied CGH to identify chromosome anomalies in 60 spontaneous abortions of the first trimester, that had failed to grow in culture. In 57 out of 60 cases CGH analyses were successful. The overall aneuploidy rate detected was 72%. Trisomy was the predominant chromosome anomaly accounting for 68.0% of abnormal abortions, followed by triploidy (17.1%) and monosomy X (9.8%). An unbalanced structural rearrangement was found in one (2.4%) abortion. Most frequently involved in trisomies were chromosomes 16 (32.1%), 7 and 22 (10.7% each), 4, 13, 15, and 21 (7.2 % each). Three triploid cases and one complete mole were detected by microsatellite analysis as supplementary method. CGH data on culture failures were compared with data derived from 4693 successfully karyotyped first trimester spontaneous abortions, resulting in a chromosome aberration rate of 64.8%. The distribution of the different chromosome anomalies was similar with the exception of a higher rate of trisomies 7 and of XYY-triploidies in the culture failures. Based on our data we suggest that the genetic contribution to pregnancy loss is still underestimated. Investigating abortion tissues hitherto unassessed by conventional methods, we suggest that the contribution of chromosome aberrations to first trimester pregnancy loss is nearly 70%.

Array-CGH testing in spontaneous abortions with normal karyotypes

“…In an attempt to overcome these problems other techniques such as fluorescent polymerase chain reaction (Diego-Alvarez et al, 2005), interphase-FISH (Horiuchi et al, 1997;Lebedev et al, 2004, Vorsanova et al, 2005, chromosome-CGH (Daniely et al, 1998;Fritz et al, 2001), MLPA (Diego-Alvarez et al, 2006) and array-CGH have been introduced in the study of POCs.…”

“…Although the array-CGH technique is not a suitable tool for detecting ploidy changes, Ballif et al (2006) described the use of a control DNA of a Klinefelter individual as an approach to identify possible ploidy alterations. All papers in the literature on studies using complementary techniques to cytogenetic analysis showed that the contribution of chromosome anomalies to first-trimester fetal losses is much greater than found by conventional cytogenetic analysis, being estimated in up to 70% (Fritz et al, 2001). For instance, when Daniely et al (1998) used chromosome-CGH in cases in which the karyotype found by cytogenetics was normal or could not be obtained due to culture failure, they detected additional numerical and structural anomalies in 8% of the POC from couples with recurrent abortions.…”

“…Thus, in addition to being a time-consuming test, karyotyping does not always lead to a result; furthermore, in about 4.4% to 29% of cases the result does not correspond to the actual fetal karyotype, mainly due to maternal cell contamination as shown by other techniques such as fluorescence in situ hybridization (FISH) and others (Bell et al, 1999;Lomax et al, 2000;Diego-Alvarez et al, 2005;Karaoguz et al, 2005;Nikitina et al, 2005) DNA-based technologies do not require dividing cells thus, overcoming one of the main limitations associated with conventional cytogenetic analysis of spontaneous abortion material. Several of these methods have been used as diagnostic tools, including fluorescent polymerase chain reaction (Diego-Alvarez et al, 2005), interphase-FISH (Horiuchi et al, 1997;Lebedev et al, 2004, Vorsanova et al, 2005, chromosome-CGH (Daniely et al, 1998, Fritz et al, 2001, and multiplex ligation probe amplification (MLPA) (Diego-Alvarez et al, 2006). More recently, array-CGH has been considered as a particularly useful alternative to conventional karyotyping in the field of diagnosis (Schaeffer et al, 2004;Benkhalifa et al, 2005;Shimokawa et al, 2006), as it allows screening gains and losses in thousands of targets simultaneously.…”

Chromosomal disorders and male infertility

“…20 The impact of aneuploidy in early embryos is illustrated by the high prevalence of chromosomal abnormalities detected in spontaneous abortions, exceeding 70% in some studies. [21][22][23][24][25][26] Removal of aneuploid embryos during assisted reproductive techniques (PGD of aneuploidy or preimplantation genetic screening) has been proposed as a way to improve success rates. 27 To date, very little is known about the role that sperm aneuploidy plays in infertility or assisted reproduction.…”

Incidence and spectrum of chromosome abnormalities in spontaneous abortions: New insights from a 12-year study

“…The utilization of comparative genomic hybridization (CGH) and interphase fluorescence in situ hybridization (iFISH) has allowed cytogenetic laboratories to evaluate POC samples that have failed to grow. 24,25 In order to determine the impact of these new techniques, an accurate representation of current abnormality rates, which reflect current reproductive trends, is needed to serve as a comparison.…”