Angelique J. A. Kooper

Identification of clinically significant, submicroscopic chromosome alterations and UPD in fetuses with ultrasound anomalies using genome-wide 250k SNP array analysis

Background The implementation of microarray analysis in prenatal diagnostics is a topic of discussion, as rare copy number variants with unknown/uncertain clinical consequences are likely to be found. The application of targeted microarrays limits such findings, but the potential disadvantage is that relevant, so far unknown, aberrations might be overlooked. Therefore, we explore the possibilities for the prenatal application of the genome-wide 250k single nucleotide polymorphism array platform. Methods Affymetrix 250k NspI single nucleotide polymorphism array analysis (Affymetrix, Inc., Santa Clara, California, USA) was performed on DNA from 38 prenatally karyotyped fetuses with ultrasound anomalies. Analyses were performed after termination of pregnancy, intrauterine fetal death or birth on DNA isolated from fetal or neonatal material. Results Aberrations were detected in 17 of 38 fetuses, 6 of whom with a previously identified chromosomal abnormality and 11 with previously normal or balanced karyotypes. Of the latter, the detected aberration occurred de novo and was considered of clinical relevance in five cases (16%), inherited from a healthy parent in four cases (12%), and de novo yet with unclear clinical relevance in two cases (6%). The clinically relevant abnormalities either were novel copy number variants (n=3) or concerned a uniparental disomy (n=2). Conclusion In at least 16% of fetuses with ultrasound anomalies and a normal or balanced karyotype, causal (submicroscopic) aberrations were detected, illustrating the importance of the (careful) implementation of microarray analysis in prenatal diagnosis. The fact that the identified, clinically relevant, aberrations would have gone undetected with most targeted approaches underscores the added value of a genome-wide approach.

Non‐targeted whole genome 250K SNP array analysis as replacement for karyotyping in fetuses with structural ultrasound anomalies: evaluation of a one‐year experience

We evaluated both clinical and laboratory aspects of our new strategy offering quantitative fluorescence (QF)‐PCR followed by non‐targeted whole genome 250K single‐nucleotide polymorphism array analysis instead of routine karyotyping for prenatal diagnosis of fetuses with structural anomalies.

Multiplex Ligation‐dependent Probe Amplification (MLPA) as a stand‐alone test for rapid aneuploidy detection in amniotic fluid cells

This study aimed to determine the diagnostic application of multiplex ligation‐dependent probe amplification (MLPA) as a stand‐alone test for targeted detection of common chromosomal aneuploidies (i.e. 13, 18, 21, X and Y) in amniotic fluid cells in routine prenatal clinical practice.

Incidental prenatal diagnosis of sex chromosome aneuploidies: health, behavior, and fertility.

Objective. To assess the diagnostic relevance of incidental prenatal findings of sex chromosome aneuploidies. Methods. We searched with medical subject headings (MeSHs) and keywords in Medline and the Cochrane Library and systematically screened publications on postnatally diagnosed sex chromosomal aneuploidies from 2006 to 2011 as well as publications on incidentally prenatally diagnosed sex chromosomal aneuploidies from 1980 to 2011. Results. Postnatally diagnosed sex chromosomal aneuploidies demonstrated three clinical relevant domains of abnormality: physical (22–100%), behavior (0–56%), and reproductive health (47–100%), while incidentally prenatally diagnosed sex chromosomal aneuploidies demonstrated, respectively, 0–33%, 0–40%, and 0–36%. Conclusion. In the literature incidental prenatal diagnosis of sex chromosomal aneuploidies is associated with normal to mildly affected phenotypes. This contrasts sharply with those of postnatally diagnosed sex chromosomal aneuploidies and highlights the importance of this ascertainment bias towards the prognostic value of diagnosis of fetal sex chromosomal aneuploidies. This observation should be taken into account, especially when considering excluding the sex chromosomes in invasive prenatal testing using Rapid Aneuploidy Detection.

Parents' perspectives on the unforeseen finding of a fetal sex chromosomal aneuploidy

To investigate the parental perspectives of being confronted with an unforeseen fetal sex chromosomal aneuploidy (SCA), in light of the fact that this accidental finding is avoidable by rapid aneuploidy detection (RAD).

Why Do Parents Prefer to Know the Fetal Sex as Part of Invasive Prenatal Testing

Objectives. The aim of this study was to determine whether prospective parents, primarily referred for prenatal diagnosis to exclude Down syndrome, prefer to know the fetal sex as part of invasive testing. Methods. In this prospective study 400 pregnant women undergoing amniocentesis were invited to answer a questionnaire, including information about demographic factors, current pregnancy, and previous children. In two open-ended questions they were asked why they wanted to know the fetal sex after amniocentesis or ultrasound investigation. Scores were given for reasons that could have played a role in the wish whether or not to know the sex of their unborn child. Results. A total of 210 (52.5%) questionnaires were completed. Overall, 69.0% was interested to know the fetal sex as part of the diagnostic test result. The most important reasons were curiosity (77.8%), “just want to know” (68.0%), and “because it is possible” (66.8%). The overall knowledge of sex chromosomal disorders appeared low and did not seem to affect the parents wish to know the fetal sex. Almost all women (96.6%) planned to have a 20-week ultrasound scan and 96.2% thought the scan to be reliable in detecting the fetal sex. A minority (28%) was willing to learn the fetal sex by ultrasound examination, whereas 65% preferred to learn the fetal sex only after the amniocentesis. Conclusion. Personal values affect the parental desire to know or not to know the fetal sex. This does not appear to be affected by invasive prenatal testing and/or genetic knowledge of sex chromosomal disorders.

Women's Attitudes towards the Option to Choose between Karyotyping and Rapid Targeted Testing during Pregnancy

Objectives. Pregnant women, referred because of an increased risk of fetal Down syndrome, who underwent an invasive prenatal procedure were offered a choice between karyotyping and rapid targeted testing. This study aims to assess womens attitudes and experiences towards what option to choose. Methods. A retrospective multicentre survey (2008–2010) was conducted among 1370 women. General questions were asked about decision making issues, followed by personal questions about their experiences in choice making, test preference, influence of others, and possible regrets. Results. In total, 90.1% of the respondents (N = 825) indicated that pregnant women are able to choose, although 33.1% stated that the choice can best be made by a professional. 18.4% indicated that making a choice places a burden on women. In 96.4%, respondents preferred to have the option to choose again in case of a next pregnancy, whereas 2.7% preferred the choice to be made by a professional. Regret was indicated by 1.2%. Decision making was influenced by others in 64.9%. A slightly higher preference for karyotyping was indicated by 52.7% of the respondents. Conclusions. Positive attitudes and experiences were expressed towards the option to choose. Respondents took decisions freely, although sometimes influenced by a partner or a professional, to follow their individual perspectives.

Is routine karyotyping required in prenatal samples with a molecular or metabolic referral

As a routine, karyotyping of invasive prenatal samples is performed as an adjunct to referrals for DNA mutation detection and metabolic testing. We performed a retrospective study on 500 samples to assess the diagnostic value of this procedure. These samples included 454 (90.8%) chorionic villus (CV) and 46 (9.2%) amniocenteses specimens. For CV samples karyotyping was based on analyses of both short-term culture (STC) and long-term culture (LTC) cells. Overall, 19 (3.8%) abnormal karyotypes were denoted: four with a common aneuploidy (trisomy 21, 18 and 13), two with a sex chromosomal aneuploidy (Klinefelter syndrome), one with a sex chromosome mosaicism and twelve with various autosome mosaicisms. In four cases a second invasive test was performed because of an abnormal finding in the STC. Taken together, we conclude that STC and LTC karyotyping has resulted in a diagnostic yield of 19 (3.8%) abnormal cases, including 12 cases (2.4%) with an uncertain significance. From a diagnostic point of view, it is desirable to limit uncertain test results as secondary test findings. Therefore, we recommend a more targeted assay, such as e.g. QF-PCR, as a replacement of the STC and to provide parents the autonomy to choose between karyotyping and QF-PCR.