Trisomy 13 or 18 (mosaicism) in first trimester cytotrophoblast cells: false-positive results in 11 out of 51 cases

OBJECTIVE: The finding of full or mosaic trisomy 13 or 18 in first trimester chorionic villus sampling (CVS) may be a false-positive result. This report provides incidence and outcome information that may be helpful in counselling individual patients and in choosing adequate follow-up. STUDY DESIGN: From a series of 6820 CVS cases, we retrospectively collected data on all patients (n=51) with full (n=30) or mosaic (n=5) trisomy 18, and full (n=13) or mosaic (n=3) trisomy 13 in cytotrophoblast cells. RESULTS: Five false-positives were seen in patients with full trisomy 18 and three in the mosaic cases. One false-positive result was observed in full trisomy 13 and two false-positives in cases of mosaicism. No false-negative results were reported. CONCLUSION: The diagnosis of trisomy 13 or 18 in cytotrophoblasts should be confirmed in other tissues, unless fetal abnormalities are seen at ultrasound. In case of mosaicism, follow-up amniocentesis is advised.     

Second-trimester placental biopsy for rapid fetal karyotyping

Since January 1988 the technique of first-trimester chorionic villus sampling (placental biopsy) has been extended to include cases in the second trimester. To date, 40 procedures have been performed. The main indication for the late chorionic villus sampling was a low serum alpha-fetoprotein value in association with an increased risk for Down syndrome (n = 28), abnormal ultrasonographic finding (n = 7), and failed amniotic cell culture (n = 3). Successful karyotype results were achieved in all but two cases. Most results were obtained within 48 hours with direct cytogenetic techniques. No cases of mosaicism were found. The highest yield of abnormal karyotypes was obtained from the cases with abnormal ultrasonographic findings (one trisomy 21, two 45,X). One case of trisomy 21 was identified in the 28 cases of low serum alpha-fetoprotein. No spontaneous losses have occurred. The technique is easy to learn, does not differ from first-trimester procedures, and may have a lower complication rate than cordocentesis. The reporting of cases to the CVS Newsletter should help evaluate late chorionic villus sampling as another method for rapid fetal karyotyping.     

Management of prenatally detected trisomy 8 mosaicism.

We report on ten pregnancies with trisomy 8 mosaicism. Nine cases were prenatally detected in chorionic villi (n=6), amniotic fluid (AF) cells (n=2) or fetal blood (FB) lymphocytes (n=1). Follow-up laboratory investigations showed confined placental mosaicism (CPM) or pseudomosaicism in eight cases. In one case with ultrasound abnormalities, trisomy 8 mosaicism was detected in FB cells although cultured AF cells showed normal cells only. Another case of mosaic trisomy 8 was prenatally missed; cytogenetic analysis of short-term cultured villi revealed a normal male karyotype, while postnatally, trisomy 8 mosaicism was detected in peripheral blood lymphocytes and skin fibroblasts of the affected child. These findings indicate the difficulties in the prenatal diagnosis of trisomy 8 mosaicism. When found in chorionic villi, it mostly represented CPM, while in a case of true fetal trisomy 8 mosaicism, the cytotrophoblast cells showed a normal karyotype. So, the cytotrophoblast compartment of chorionic villi is a poor indicator of the presence or absence of fetal trisomy 8 mosaicism. Follow-up investigations including amniocentesis and especially fetal blood sampling are required to come to a definite prenatal diagnosis of trisomy 8 mosaicism.     

FISH analysis of fetal nucleated red blood cells from CVS washings in cases of aneuploidy.

OBJECTIVE: In chorionic villus sampling (CVS) the chromosome analysis is inconclusive in 1-2% of the samples. In many cases follow-up amniocentesis is performed. Fetal nucleated red blood cells (FNRBCs) are present in washings of chorionic villus samples. We wanted to establish whether analysis of these true fetal cells, using fluorescence in situ hybridization (FISH), could support the CVS karyotype. METHODS: We analysed washings of first trimester chorionic villi from non-mosaic 45,X (n=6) and full trisomy 18 cases (n=7). FNRBCs were identified by immunostaining and FISH was performed with chromosome-specific probes for X, Y and 18. RESULTS: In all 13 samples FNRBCs were present (between 4 and 30 cells per sample). Five cases of monosomy X showed one X signal in 89-100% of the nuclei; in the other case 50% of the nuclei displayed one signal. In the trisomy 18 cases three spots were seen in 60-100% of the cells. CONCLUSION: The CVS aneuploidy was confirmed in FNRBCs in all samples, so FISH on FNRBCs can be used in cases of non-mosaic numerical chromosomal abnormalities. This test can confirm a CVS diagnosis of monosomy X or trisomy 18 and thus minimize the risk for false-positive diagnoses. An additional invasive test may be prevented.     

Prenatal diagnosis of trisomy 18: report of 30 cases

OBJECTIVES: To review the detection rate of the prenatal screening tests used for the diagnosis of the trisomy 18. METHODS: From 1 October 1998 to 31 December 2001, we reviewed the database and medical records of 30 cases of trisomy 18. All were singletons and trisomy 18 was confirmed by amniocentesis in 19 cases, by cordocentesis in 6 cases, by chorionic villi sampling in 2 cases and by skin biopsy in 3 cases. RESULTS: Of the 30 study cases, 23 cases (77%) were offered genetic study due to abnormal ultrasound (US) findings. Twelve (40%) out of the 23 cases were due to abnormal US findings detected before the triple test and 11 (37%) were due to abnormal US findings after the normal triple test. Six cases (20%) were offered genetic study because of an abnormal triple test, and one case was offered genetic study due to advanced maternal age only. Including the second targeted ultrasonogram, one or more abnormal US findings were found in all 30 fetuses. CONCLUSIONS: Abnormal US finding is the most sensitive screening test for trisomy 18. The most sensitive ultrasonographic finding for trisomy 18 at under 16 weeks of gestation is increased nuchal translucency (75%) and, after 16 weeks, is cardiac defect (83%).     

Postnatal placental confirmation of trisomy 2 and trisomy 16 detected at chorionic villus sampling: a possible association with intrauterine growth retardation and elevated maternal serum alpha-fetoprotein.

Detection of trisomy 2 and trisomy 16 mosaicism through chorionic villus sampling (CVS) is not an infrequent finding. We describe here two cases, one of non-mosaic trisomy 2 and the other of high level mosaicism for trisomy 16. Amniocentesis in both cases demonstrated non-mosaic 46,XY karyotypes. Each pregnancy continued to delivery of liveborn, normal-appearing boys; both pregnancies were complicated by severe intrauterine growth retardation (IUGR). Postnatal studies of placental biopsies in both cases confirmed the original CVS findings, whereas cord blood karyotypes were normal in both boys. Both children have demonstrated adequate catch-up growth.     

Chorionic Villus Sampling: Cytogenetic Experience in Preliminary Investigations and in 50 Diagnostic Cases

The results of preliminary cytogenetic investigations of chorionic villus sampling (CVS) and its diagnostic application in 50 cases are reported. Preliminary investigations included the effect of short delays between biopsy and processing, levels of mitotic activity related to variations in processing, the incidence of tetraploidy, correlation of the karyotype of the chorionic villi with that of the fetus, and the results of banding studies. A protocol was then designed for application to diagnostic CVS. The 50 diagnostic cases included 4 with male karyotypes which were terminated due to a family history of an X-linked disorder, 1 trisomy 21, 1 trisomy 18, the finding of 1 aberrant cell out of 50 in an otherwise normal analysis, a 45, XY, t (13;21) karyotype, 2 fragile X negative karyotypes and in one case the presence of mosaicism was detected in chorionic villi and subsequently not confirmed at amniocentesis. The karyotype on the chorionic villi was 46XY/47XY +3.     

Introduction of the QF-PCR analysis for the purposes of prenatal diagnosis in Bulgaria--estimation of applicability of 6 STR markers on chromosomes 21 and 18

OBJECTIVE: The aim of our study was to estimate the observed heterozygosity and informativeness of 6 STR markers on chromosomes 18 and 21 in the Bulgarian population. We have evaluated the applicability of these markers used from other investigators for QF-PCR prenatal diagnosis of the most common autosomal aneuploidies in Bulgaria. METHODS: DNA samples (n = 486) were extracted from different fetal tissues (amniotic fluid cells, chorionic villus samples, and fetal tissue after abortions). PCR amplifications of 4 STR markers located on chromosome 21 (D21S11, D21S1411, D21S1270, and D21S1440) and 2 on chromosome 18 (D18S535 and D18S51) were performed. They were analysed on an automated sequencer, and the allele dosage ratios were calculated. RESULTS: The results indicate the selected markers as highly informative for our population and suitable for QF-PCR prenatal diagnosis in Bulgaria. All samples with trisomy 21 (n = 8), trisomy 18 (n = 4) and triploidy (n = 1) were correctly detected by our analysis. Thus, no false-negative results were observed. CONCLUSION: QF-PCR analysis could be an applicable alternative in prenatal and postnatal diagnosis in cases with a strong suspicion for particular autosomal aneuploidies (including chromosomes 21, 18, and 13) in small countries with limited resources like Bulgaria.     

The triple-marker test in predicting fetal aneuploidy: a compromise between sensitivity and specificity

OBJECTIVE: to review the contribution of unconjugated estriol in Down's syndrome detection, and influence of maternal age, cut-off choice, and population specificity on the balance between triple-marker test sensitivity and specificity. STUDY DESIGN: Prenatal karyotyping was performed in 2833 pregnant women, 73% of them over the age of 34. Duration of gestation was determined by ultrasound in 98% of women. Prior to amniocentesis, the serum levels of alpha-fetoprotein, human chorionic gonadotropin and unconjugated estriol were evaluated and corrected for weight. The risk of trisomy 21 was calculated for the first 986 subjects using default medians, and for 1847 by our population-specific medians. The cut-off was initially 1:300 at term, but the 1:100 and 1:200 risks were also tested. Down syndrome risk was calculated with alpha-fetoprotein and human chorionic gonadotropin combination as well. Linear logistic regression model was performed to test the ability of aneuploidy markers to classify patients into normal and trisomic groups. RESULTS: There were twelve cases of Down's syndrome, seven of trisomy 18, four of trisomy 13, and one trisomy 22. Four cases of aneuploidy (16.7%) referred to women younger than 35. With the cut-off risk of 1:300, detection rate was 87.5% and specificity 63.3%, and with 1:100, 66.7% and 79.5%, respectively. The sensitivity for Down's syndrome was from 75% for cut-off=1:100 to 92% for cut-off=1:300, while detection of other trisomies was less successful (58% and 83%, respectively). Exclusion of unconjugated estriol MoM from the risk calculations reduced detection rate by 33% and improved specificity by 4% independently of cut-off choice. Linear logistic regression analysis showed that only unconjugated estriol was able to correctly classify patients between normal and trisomy 21 (p=0.011, odds ratio=1.445), and normal and trisomy 18 (p=0.0023, odds ratio=1.96) groups. CONCLUSIONS: The unconjugated estriol significantly contributes in Down's syndrome detection with cost of slightly reduced specificity. The 1:300 risk caused an unfavorable compromise between sensitivity and specificity. A higher cut-off, 1:100, would indicate performance of amniocentesis in women aged 39 years and older, and in those aged 35-39 only after the screen-positive result.     

Confirmation rates of array-CGH in day-3 embryo and blastocyst biopsies for preimplantation genetic screening

Purpose

The purpose of this study was to compare the confirmation rate of day-3 embryo biopsy (blastomere) and trophectoderm biopsy using array-comparative genomic hybridization (array-CGH) technology.

Methods

A blinded study was conducted to re-analyse 109 embryos previously diagnosed as chromosomally abnormal by array-CGH. Preimplantation genetic screening (PGS) was performed using array-CGH on day 3 (n = 50) or day 5 (n = 59). Partial chromosome gains or losses were excluded (n=6), and only whole chromosome aneuploidies were considered. Re-analysis of whole blastocysts was carried out following the same array-CGH protocol used for PGS.

Results

The PGS result was confirmed in the whole blastocyst in (a) 49/50 (98 %) abnormal embryos after day-3 biopsy and (b) 57/59 (96.6 %) abnormal embryos after trophectoderm biopsy. One embryo (1/50; 2 %) was diagnosed as abnormal, with monosomy 18, on day 3, and software analysis of the whole blastocyst gave a euploid result; however, a mosaic pattern was observed for monosomy 18 in the whole blastocyst. Two trophectoderm biopsy cases (3.4 %) did not have the abnormalities (trisomy 7, and trisomy 1 and 4, respectively) verified in the whole embryo. Concordance rates for both biopsy strategies and for individual chromosomes were evaluated by Fisher’s exact test and showed no significant differences.

Conclusions

Both types of biopsies showed similar high concordance rates with whole blastocyst results. Therefore, regarding the confirmation rates shown in this work, day-3 embryo biopsies can be representative of the whole embryo and both types of biopsy can be used for clinical analysis in PGS following the described array-CGH protocol.     

Chorionic villus sampling for first-trimester prenatal diagnosis: Northwestern University program

We present our initial experience in developing a chorionic villus sampling program at Northwestern University. In phase 1, we performed chorionic villus sampling in 58 patients prior to elective first-trimester abortion, assessing the reliability and reproducibility of obtaining adequate villus samples and performing cytogenetic analysis by means of both the direct and culture methods. Specimens were categorized according to quality: class I, multiple identifiable villi (n = 20); class II, few villi or villi mixed with decidua (n = 15); class III, no villi (n = 23). There was a positive trend between operator experience, amount of villi obtained, and quality of cytogenetic preparations. In March, 1984, we received Institutional Review Board approval to perform chorionic villus sampling in continuing pregnancies (phase 2). Among the first 20 cases we found two abnormalities (47,XY, + 13; 45,X). The remaining 18 pregnancies were continuing. Recommendations are made for developing a chorionic villus sampling program.     

Prenatally detected trisomy 20 mosaicism

BACKGROUND: Trisomy 20 is one of the more common mosaic trisomies detected on amniocentesis and presents with a normal outcome in over 90% of reported cases. Trisomic cells are almost never confirmed in newborn blood and are only rarely found in other fetal or placental samples. Nonetheless, some abnormal outcomes have been reported, including unexplained fetal demise, intrauterine growth restriction, and multiple congenital anomalies. Because of the lack of molecular studies on such cases, it is unknown whether the origin of trisomy or presence of uniparental disomy (UPD) could have some influence on outcome. METHODS: We present data on six cases of trisomy mosaicism, two detected by chorionic villous sampling (CVS) and four by amniocentesis (AF), submitted to our laboratory for molecular studies. RESULTS AND CONCLUSIONS: A meiotic origin of the trisomy could be confirmed in only one of these cases. In addition, uniparental disomy was excluded in all four cases for which parents were available for testing. The four cases with low levels of trisomy in amniotic fluid (0%, 10%, 11%, and 12%) were associated with a normal outcome. The remaining two cases of trisomy 20 had high levels of trisomy in amniotic fluid (96% and 58%) and had abnormal outcomes (developmental delay in one and stillbirth with IUGR and severe oligohydramnios in the other). Including previously published cases, there is a clear association with the level of trisomy and outcome, with only 4% abnormal outcomes when <40% trisomic cells were detected. Higher levels of trisomy were also observed in male fetuses as compared to female fetuses (p = 0.01); however, there were no sex differences in frequency of abnormal outcomes.     

A comparison of prenatal versus postnatal karyotyping for the investigation of intrauterine fetal death after the first trimester of pregnancy

INTRODUCTION: Aneuploidy is an important cause of intrauterine fetal death (IUFD) after the first trimester. Determination of the fetal karyotype of these pregnancies is commonly done in most units from solid tissues. Results from such techniques are disappointing. The aim of this audit was to compare the results of karyotyping IUFD by invasive testing (amniocentesis or chorionic villus sampling) and solid tissues (skin biopsy). SUBJECTS AND METHODS: Women with IUFD managed in our unit between 1 January 1998 and 31 December 2002 (inclusive) were offered either invasive testing before medical induction of labour or solid tissue biopsy after delivery. The amniotic fluid, chorionic villi and biopsies were processed following standard laboratory procedures. RESULTS: During the 60 months, 230 samples from cases of IUFD were received by the laboratory in our unit; 126 had skin biopsies and 104 underwent invasive testing (81 amniocenteses and 23 chorionic villus sampling). Successful karyotyping was possible in 90% of those who underwent amniocentesis, 100% of those who had chorionic villus sampling and 13.5% of those who had skin biopsies. 50% of skin biopsies were unsuitable for analysis compared to none in the CVS and amniocentesis group. The difference in successful karyotyping between invasive testing and solid tissue testing was statistically significant (P < 0.0001). There were 12 (10.6%) abnormal karyotypes from the 113 successful samples (11/96 in the invasive group versus 1/17 in the solid tissue group). CONCLUSION: Invasive testing has a much higher success rate of karyotyping in cases of IUFD and should, therefore, be offered to women presenting with this complication irrespective of gestational age.     

Seven cases of trisomy 3 mosaicism in chorionic villi

This paper describes seven cases of confined chorionic mosaicism with trisomy 3. The chromosomally abnormal cell line in chorionic villi was revealed in three cases at diagnostic CVS and in four cases at the evacuation of the uterine cavity after a missed abortion had been diagnosed by ultrasound. In two of these cases, the abortion occurred after apparently normal development of the fetus during the second trimester of pregnancy. An evaluation of the effect of confined chorionic mosaicism with trisomy 3 on the viability of the conceptus has been attempted.     

Trisomy 7 in chorionic villi: follow-up studies of pregnancy, normal child, and placental clonal anomalies

Cytogenetic study of chorionic villi sampled because of advanced maternal age revealed, after overnight culture, an apparently non-mosaic trisomy 7. Amniocentesis showed exclusively normal mitoses, and the pregnancy continued normally. One hundred mitoses from cord blood of the normal newborn revealed a non-mosaic 46,XX complement. No cells with a proven trisomy 7 were found in cultures from either of two biopsies of the morphologically normal placenta, but the peripheral biopsy showed in multiple cultures an abnormal clone: 47,XX, +20, -2, -21, +t(2;21)(p13;q22). To our knowledge, this is the first case of non-mosaic trisomy 7 detected on CVS which has had follow-up studies of amniotic fluid, cord blood, and term placenta.     

基因芯片技术对流产胚胎组织遗传学诊断的研究

目的:探讨基因芯片技术在早期自然流产胚胎组织遗传学诊断中的临床应用价值。方法:选取第四军医大学第一附属医院自然流产就诊的孕妇58例,获取流产胚胎组织,提取组织DNA,进行基因芯片检测。结果:基因芯片检测的成功率为100.0%,检测结果正常14例,异常44例,检出率为75.9%(44/58)。检出的异常结果中染色体数目异常共26例,包括三倍体4例,非整倍体22例;结构异常共18例,包括微缺失和微重复12例,多条染色体异常及部分单亲二倍体(UPD)6例。结论:基因芯片技术能准确检出染色体异常,可以建立一种非培养、快速、准确的流产胚胎染色体异常的检测方法,在流产组织遗传学诊断中具有较强的临床应用价值。     

无阴道镜条件下宫颈病变随机点活检位置研究

目的:通过回顾分析阴道镜引导下活检诊断宫颈高级别鳞状上皮内病变(HSIL)患者的活检位置,寻找宫颈最易发生病变的位置,探讨肉眼引导下宫颈随机取材检查的循证方法。方法:回顾分析复旦大学附属妇产科医院2015年1月1日至2015年12月31日阴道镜引导下宫颈点活检诊断HSIL者活检的位置和个数。结果:阴道镜引导下点活检诊断宫颈HSIL 1096例,共活检3563个点,平均3.25点/例。按每个位置点活检比例从高到低排列,依次为12点(16.0%)、6点(15.5%)、1点(10.2%)、7点(10.0%)、11点(9.6%)、5点(9.0%)、9点(8.6%)、3点(8.1%)、10点(4.0%)、4点(3.2%)、8点(3.0%)、2点(2.8%)。点活检数选择方面,按比例从高到低排列,依次为四点活检(42.2%)、三点活检(30.5%)、两点活检(19.7%)、五点活检(3.7%)、单点活检(3.3%)、六点活检(0.5%)。单点活检、两点活检、三点活检和四点活检中,最常见的两个活检位置均为12点和6点。结论:12点、6点、1点、7点可能是最易首先发生宫颈病变的位置。在无阴道镜的条件下,选择这四个点位检查可能对提高宫颈病变的检出率和正确性具有重要意义。     

Abortion risk in chorionic villus sampling. Evaluation in elective termination of pregnancy

100 patients were examined to evaluate the risk of abortion of chorionic villus sampling. In the 8th-10th week of pregnancy a catheter with a mandrin was introduced into the chorion frondosum under ultrasound guidance. The mandrin was then removed and trophoblast tissue obtained by aspiration. The patients agreed to postpone elective termination of pregnancy for 2 weeks. Another ultrasound was performed before suction curettage. With increasing experience, the abortion rate dropped to 4%, whereas the rate of successful biopsies and analyses rose to more than 90%. Based on these results, chorionic villi sampling was made available at the 1st Department of Obstetrics and Gynecology, University of Vienna, as an alternative method to amniocentesis. Out of 38 biopsies, 25 karyotypes were normal, two biopsies revealed pathological results (trisomy 21, 22), 11 samples showed no results (insufficient tissue or no mitoses). One patient had a spontaneous abortion (trisomy 22) and one an abortion due to infection. Chorionic villus sampling could replace amniocentesis because chromosomal anomalies may be detected already in the 1st trimester of pregnancy.     

Four years' cytogenetic experience with the culture of chorionic villi

In 1958 chorionic villus samples, investigated by culture method, we found 137 (7%) abnormalities. The abnormal results were classified in certain abnormal (generalised abnormal at high probability) and uncertain abnormal (potentially confined to the placenta) results. Certain abnormal were 73 cases (3.7%). Uncertain abnormal were 64 cases (3.3%), in which confirmation studies were done in 47 cases. In 12 cases of these 47, the abnormality was confirmed and in 35 cases (1.8%) the abnormality was confined to the placenta. Among the latter cases, poor pregnancy outcome [16% intrauterine death (IUD), 6% intrauterine growth retardation (IUGR)] was increased. Total maternal cell contamination was not seen. The positive predictive value of all confirmed abnormal cases was 66%. The positive predictive value was 100% for indications 'ultrasound abnormalities' and 'carrier' and between 50 and 60% for all other indications. Predictive value among uncertain abnormal cases was low (26%). However, the positive predictive value depends of the type of abnormality. Therefore we conclude that the culture method for chorionic villi is a good test for indications 'ultrasound abnormalities' and 'carrier' and reliable for all other indications. Whether or not follow-up investigations should be offered to the parents depends of the type of abnormality. We conclude that the culture method is reliable for prenatal diagnosis and can be used as the sole investigative method.     

Fetal nuchal cystic hygromata: associated malformations and chromosomal defects.

During a 6-year period (1985-1990), blood karyotyping was performed in 44 fetuses with septated, bilateral, dorsal, cervical cystic hygromata. This condition constitutes a different entity from nuchal oedema. There were 33 (75%) chromosomal abnormalities, including Turner's syndrome (n = 31), trisomy 18 (n = 1) and trisomy 21 (n = 1). Congenital heart defects (CHD), mainly coarctation of the aorta, were present in 15 of the fetuses with Turner's and in 1 of the chromosomally normal fetuses. The incidence of CHD was higher in the fetuses with ultrasonographic evidence of moderate/severe hydrops (41%; 13 of 32 cases) than in those with mild or no hydrops (25%; 3 of 12 cases). Although both the biparietal diameter (BPD) and femur length (FL) were reduced in all fetuses, the FL to BPD ratio was below the 5th percentile in 29 of the 33 (88%) chromosomally abnormal fetuses, but in only 4 of the 11 (36%) chromosomally normal ones. In the chromosomally normal group, 3 of the fetuses had multiple pterygium syndromes, and in such cases the risk of recurrence may be high. In contrast, in the group of mutant chromosomal disorders with monosomy or trisomy, the risk of recurrence is in the order of 1%.