Correlation between rare chromosomal abnormalities and prenatal ultrasound findings.

Our objective was to examine ultrasound findings with outcomes in cases of rare chromosomal abnormalities diagnosed during pregnancy. Results of cytogenetic studies obtained from amniocenteses and chorionic villus samplings (CVS) from 1994-2000 were reviewed. Only those examples of rare chromosomal abnormalities with little information on the associated outcome were included. Cases of autosomal trisomy (13, 18, and 21), sex chromosome aneuploidy, and reciprocal or Robertsonian translocations were excluded. Ultrasound findings and outcomes were reviewed. In all, 8,642 procedures of amniocenteses and 557 of CVS were performed; 21 cases met the inclusion criteria. Parental karyotypes were obtained for 19 couples and the karyotypic abnormalities were de novo in 13. Abnormal ultrasound findings were present in 14 pregnancies, with the following outcomes: seven underwent dilatation and evacuation (D&E), with abnormal findings in two (although examination was limited by fragmentation); one medical termination with micrognathia and low-set ears; one fetal demise; one neonatal demise; three surviving neonates with abnormalities (one each with congenital kyphosis, hydronephrosis, and hypotonia), and one newborn was normal. There were seven patients without abnormal ultrasound findings with the following outcomes: three underwent D&E, with abnormal findings in two, one child with a colobomatous optic nerve, and two apparently normal infants. Follow-up was not available in one patient. We conclude that when rare karyotypes and ultrasound abnormalities are present, poor outcomes are likely. Even with normal ultrasound findings, abnormalities may be present. These data may assist in counseling patients when testing reveals such chromosomal abnormalities.     

产前诊断中胎儿新发生染色体异常的临床结局与遗传咨询

目的 分析在产前诊断中胎儿新发生染色体异常的检测结果和临床结局,为胎儿新发生染色体异常的遗传咨询积累有价值的临床资料.方法 2006年1月至2009年12月,在2583例产前诊断的细胞染色体核型分析中,共发现12例新发生的胎儿染色体异常,回顾性分析这12例胎儿的细胞和(或)分子细胞遗传学检测结果、产前超声检查结果、妊娠结局和出生后的随访结果.结果 12例新发生染色体异常的胎儿有10例是非平衡性染色体异常,2例平衡性染色体异常.10例非平衡染色体异常的胎儿中有8例引产终止妊娠,有2例足月顺娩,其中1例是标记染色体异常出生后随访未见异常,另1例出生后随访至2周岁发现语言功能发育迟缓.2例平衡性染色体异常的胎儿均足月顺娩,出生后随访未发现异常.结论 新发生染色体异常的胎儿表型可通过详细的染色体核型分析以及进一步的分子细胞遗传学检测所提供的染色体成分进行预测,产前超声结构畸形检查可为妊娠结局的评估提供有力的参考依据.

Abstract：

Objective To analyze the chromosome rearrangements and clinical outcome in fetus detected at prenatal diagnosis, and provide information for genetic counseling about de novo chromosomal aberrations. Methods From January 2006 to December 2009, we found 12 cases of de novo chromosomal aberrations in 2 583 cases of prenatal cytogenetic analyses and reviewed the karyotypes, other experimental analyses data, fetal ultrasound findings and clinical outcomes. Results Out of the 12 de novo chromosomal aberrations, 10 had unbalanced translocations and 2 had balanced reciprocal translocations. Eight of the 10unbalanced translocation cases were terminated therapeutically, and 2 were delivered with full term.Neonates were phenotypically normal in the 2 cases with unbalanced translocations, but 1 had language retardation when followed up. The two balanced translocation cases were delivered with full term, and the neonates were phenotypically normal and clinical examinations were normal too. Conclusion Detailed cytogenetic and molecular study will be adjunctive tools for predicting the phenotype of fetus with de novo chromosomal aberrations. Fetal ultrasound examination will provide convincible demonstration to determine the outcome of pregnancy.     

Fetal ultrasound abnormalities: Correlation with fetal karyotype,autopsy findings,and postnatal outcome—five-year prospective study

A 5-year prospective prenatal study in 151 pregnancies with 152 malformed fetuses detected by ultrasound was evaluated cytogenetically. Thirty-five fetuses (23%) had abnormal karyotypes. Specific anatomical fetal malformations identified by ultrasound increase the risk for fetal chromosome abnormalities. Risks of abnormal chromosomes in the fetus are present with both single and multiple anomalies including amniotic fluid volume although the risk is increased with specific anatomical systems and multiple malformations. An abnormal fetal karyotype was present in 17% with a single anatomical abnormality and 30% when two or more anatomical systems were involved. Fetal hydrops, duodenal atresia, and omphalocele were the most specific single ultrasound anomalies; fetal hydrops, IUGR, holoprosencephaly, congenital heart disease, diaphragmatic hernia, duodenal atresia, and omphalocele were the most specific multiple anomalies with abnormal amniotic fluid volume. Termination of pregnancy occurred in 32/58 patients diagnosed prior to the 20th week of pregnancy with most (31/32) having a chromosomal anomaly or severe fetal anomaly. Fetuses terminated after the 20th week had chromosomal (7/18) or lethal fetal anomalies (11/18). The most common aneuploidies were trisomy 21, trisomy 18, and 45,X. The decision to terminate the pregnancy was based in most cases on the fetal ultrasound findings. Correlation of ultrasound and clinical findings is important for accurate genetic counselling. © 1992 Wiley-Liss, Inc.     

The centralized prenatal genetics screening program of New York City: I. Developmental phase

The increasing demand in New York City for prenatal diagnosis of genetic disorders has necessitated the development of a large-scale, centralized prenatal genetic screening program. The objective of this program is eventually to serve 3,000 to 4,000 at-risk New York City pregnant women annually. Through the teamwork of a task force comprising representatives from the New York Scientists' Committee for Public Information (SCPI), the Medical and Health Research Association of New York City, Inc. (MHRA), the New York State and New York City Departments of Health, and five different advisory committees, the centralized Prenatal Diagnosis Laboratory of New York City (PDL) was designed and established. While this program aims to provide high quality, centralized laboratory service for the prenatal detection of chromosome abnormalities and open neural tube defects, it also emphasizes quality-controlled services in genetic counseling, amniocentesis, ultrasound monitoring, obstetric care, and patient follow-up. Genetic counseling by PDL-employed counselors is made available to patients whenever the participating hospital lacks such service or cannot handle their patient load. In addition, PDL has launched a vigorous public health education program. A detailed guideline for the program was prepared describing the highest standards of quality for each component. The initial step was the developmental phase that included establishing the advisory committees, searching for sponsors, preparing guidelines, developing the health education program, renovating the laboratory site, purchasing and installing equipment, and recruiting of staff. The experience gained from this endeavor will be value in the development of similar large-scale prenatal diagnosis programs.     

荧光原位杂交技术在复杂染色体异常产前诊断中的应用

目的 探讨荧光原位杂交技术(fluorescence in situ hybridization,FISH)在复杂染色体异常产前诊断中的应用价值.方法 对8例羊水、3例脐血常规G显带具有复杂染色体异常的产前诊断孕妇,应用FISH技术确定其复杂染色体重排及标记染色体的组成.结果 FISH技术证实了G-显带平衡易位的结果,同时明确了3例羊水中衍生染色体的组成、2例脐血中标记染色体的来源.结论 FISH技术具很高的敏感性和特异性,是明确染色体异常重要的分子细胞遗传学工具,其在产前诊断中的应用,可为临床提供更准确全面的实验依据.     

Rare chromosome abnormalities, prevalence and prenatal diagnosis rates from population-based congenital anomaly registers in Europe

The aim of this study is to quantify the prevalence and types of rare chromosome abnormalities (RCAs) in Europe for 2000-2006 inclusive, and to describe prenatal diagnosis rates and pregnancy outcome. Data held by the European Surveillance of Congenital Anomalies database were analysed on all the cases from 16 population-based registries in 11 European countries diagnosed prenatally or before 1 year of age, and delivered between 2000 and 2006. Cases were all unbalanced chromosome abnormalities and included live births, fetal deaths from 20 weeks gestation and terminations of pregnancy for fetal anomaly. There were 10,323 cases with a chromosome abnormality, giving a total birth prevalence rate of 43.8/10,000 births. Of these, 7335 cases had trisomy 21,18 or 13, giving individual prevalence rates of 23.0, 5.9 and 2.3/10,000 births, respectively (53, 13 and 5% of all reported chromosome errors, respectively). In all, 473 cases (5%) had a sex chromosome trisomy, and 778 (8%) had 45,X, giving prevalence rates of 2.0 and 3.3/10,000 births, respectively. There were 1,737 RCA cases (17%), giving a prevalence of 7.4/10,000 births. These included triploidy, other trisomies, marker chromosomes, unbalanced translocations, deletions and duplications. There was a wide variation between the registers in both the overall prenatal diagnosis rate of RCA, an average of 65% (range 5-92%) and the prevalence of RCA (range 2.4-12.9/10,000 births). In all, 49% were liveborn. The data provide the prevalence of families currently requiring specialised genetic counselling services in the perinatal period for these conditions and, for some, long-term care.     

评价羊水染色体检测在产前诊断中的作用

目的评价羊水细胞染色体检测在产前诊断中的作用。方法对妊娠16∽24w的孕妇939例进行羊膜腔穿刺术,对羊水细胞染色体分析。结果检测出染色体异常共54例,其中21-三体13例,18-三体1例,13-三体1例,性染色体异常9例,平衡易位14例,其他染色体结构异常16例。结论羊水染色体检测可安全、有效的检测胎儿染色体异常,具有重要意义,值得进一步推广。     

孕妇产前诊断指征与胎儿染色体异常的关系

目的探讨产前诊断指征和产前诊断胎儿染色体异常间的关系。方法选择2018年6月至2018年12月于贵港市人民医院就诊的孕妇100例,收集所有孕妇产前诊断指征的资料,同时收集羊膜腔穿刺术检测胎儿染色体核型分析的结果。结果胎儿染色体异常共9例,总异常率占9.00%,其中无创基因检测异常组的胎儿染色体异常检出率为60.00%,明显高于高龄组的3.03%、唐氏筛查高危组的5.26%及胎儿超声异常组的7.69%,差异均有统计学意义(P<0.05);夫妇染色体异常组的胎儿染色体异常检出率为50.00%,明显高于高龄组,差异均有统计学意义(P<0.05);高龄组、唐氏筛查高危组、胎儿超声异常组间异常检出率无明显差异(P>0.05)。结论产前诊断指征与胎儿染色体异常密切相关,羊膜腔穿刺行染色体核型分析,能够有效检出胎儿染色体异常,对于有产前诊断指征的孕妇应尽早接受产前诊断,以降低新生儿出生缺陷的发生率。     

Application of chromosomal microarray in the evaluation of abnormal prenatal findings

We performed karyotype and array comparative genomic hybridization (aCGH) analyses on 177 prenatal samples, including 162 (92%) samples from fetuses with sonographic anomalies. Overall 12 fetuses (6.8%) had abnormal karyotype and 42 (23.7%) fetuses had abnormal microarray results: 20 (11.3%) with pathogenic copy number variations (CNVs), 16 with CNVs of uncertain clinical significance, 4 with CNVs establishing carrier status for recessive, X‐linked, or susceptibility to late onset dominant disease, and two CNVs with pseudomosaicism due to in vitro cultural artifacts. For 23 pregnancies (13%), aCGH contributed important new information. Our results highlight the interpretation challenges associated with CNVs of unclear significance, incidental findings, as well as technical aspects. Array CGH analysis significantly improved the detection of genomic imbalances in prenatal diagnosis of pregnancies with structural birth defects.     

An evaluation of maternal cell contamination in cultures of chorionic villi for the prenatal diagnosis of chromosome abnormalities

Culture of chorionic villus cells provides a method of obtaining chromosomes of excellent quality for first trimester prenatal diagnosis. Concern exists that maternal cells present in the biopsy may contaminate the culture and lead to misdiagnosis. This study has confirmed that karyotypes obtained from female villus cultures were non-maternal by establishing the presence of paternal markers using Q- and C-banding. Male cultures were harvested serially to investigate the possibility of maternal cell overgrowth. Of 82 successful cultures investigated, 37 were male and 45 female and of the males 4 contained a mixture of male and female cells. Thorough dissection of the material is essential if maternal cell contamination is to be mininimised. The use of heteromorphic chromosome markers to establish that fetal cells have grown provides valuable reassurance.     

妊娠孕妇产前超声检查胎儿心脏异常表现与染色体异常的相关性

目的探究妊娠孕妇产前超声检查胎儿心脏异常表现与染色体异常的相关性。方法回顾性分析我院2016年2月-2018年2月产前检查的500例胎儿心脏超声检查及染色体核型分析结果,分析心脏异常与染色体核型分析结果的相关性。结果本研究中共有26例发生胎儿心脏异常,37例存在染色体异常,26例胎儿心脏异常中共有19例发生染色体异常,发生率为73.08%。26例发生心脏异常的胎儿主要为室间隔缺损、卵圆孔未闭、三尖瓣轻度反流、左室功能异常,其中室间隔缺损发生率最高,其染色体异常率占总异常率的18.92%,三尖瓣轻度反流最低,占5.41%。将上述数据代入Spearman检验后发现,胎儿心脏异常表现与染色体异常成正相关(P<0.05)。结论妊娠孕妇产前超声检查胎儿心脏异常表现与染色体异常存在正相关,当胎儿出现心脏结构畸形时,胎儿染色体异常发生率较高,临床在超声检查应尤为注意。     

Usefulness of a registry of congenital malformations for genetic counseling and prenatal diagnosis

During three years, 39,924 infants born consecutively in the area covered by our registry of congenital malformations were surveyed; 775 had major congenital malformations. Recurrence risks for the major malformation was estimated and classified as high (greater than 10%, 5.3% of the cases), low (1 to 10%, 85.3% of the cases) or occasional (less than 1%, 9.4% of the malformed). Feasibility of prenatal diagnosis was considered. On the basis of the recurrence risk of 1% or higher and the feasibility of prenatal diagnosis, such a procedure should be considered in future pregnancies in 64.1% of the mothers. Genetic counseling has to be given to couples at risk of having a malformed child. For this purpose, as is shown in our study, the best way is the possibility of using a registry of congenital malformations.     

Rates of Down syndrome at livebirth by one-year maternal age intervals in studies with apparent close to complete ascertainment in populations of European origin: A proposed revised rate schedule for use in genetic and prenatal screening

Precision and accuracy in determining rates of Down syndrome at livebirth are indispensible to algorithms which determine eligibility for prenatal cytogenetic diagnostic services. We derived Down syndrome rates by single year of maternal age which we propose as a revised rate schedule for background risk. Data on European-origin populations were obtained from 5 sources judged most likely to have complete ascertainment of cases. A “constant plus exponent” regression model and variants extending the analysis to higher powers of maternal age were applied to several ranges of maternal age. Confidence intervals about the rates were calculated. This analysis results in rates significantly higher than those in widespread use though the confidence intervals show a need for caution in assuming precision. Sources of variation in rates are also considered. © 1996 Wiley-Liss, Inc.     

Chromosome abnormalities and rare fragile sites detected in azoospermia patients

Summary We have examined constitutional chromosome abnormalities and fragile sites in 40 patients with azoospermia. Chromosome abnormalities were found in four cases. Three cases showed a deletion of the long arm of the Y chromosome 46,X,del(Yq) and the other case had a ring of G group chromosome 46,XY,r(G). In a rare fragile sites test, four fragile site carriers were detected and three rare autosomal fragile sites were identified; fra(8)(q24.1), fra(11)(p15.1), and fra(17)(p12). The expression of these fragile sites were induced specifically by AT-specific DNA ligands, such as distamycin A and Hoechst 33258. In addition, one patient was found to be the case of double ascertainment of fragile sites, fra(8)(q24.1) and fra(17)(p12). The overall frequency of distamycin A-inducible fragile sites in azoospermia patients appeared to be higher than those reported for Japanese healthy subjects and cancer patients. However, no significant relation among fragile sites, clinical and histological findings has been detected so far.     

Properties and significance of a small marker chromosome in amniotic fluid cells

We report the presence of a small supernumerary metacentric chromosome in an amniotic fluid cell culture. The extra chromosome was inherited from the mosaic mother, and was characterized by the presence of four satellite regions, two on each side of the centromere. The pregnancy proceeded to term, and our findings were confirmed in the clinically normal offspring. The problems posed by the presence of the marker chromosome, in terms of both cytogenetic diagnosis and genetic counseling, are discussed in the light of similar cases from the literature.     

胎儿脑中线结构异常的产前超声诊断简

目的探讨产前常规超声检查对胎儿脑中线结构异常的临床应用价值。方法回顾性分析经常规超声检查怀疑有脑中线结构异常的胎儿178例,孕妇年龄19-43岁,平均年龄30．7岁,孕周14-38周。平均孕周28．4周。所有胎儿均经腹扫查．应用二维或三维超声扫查模式．总结并归纳其声像图特征。超声怀疑有脑中线结构异常的胎儿可行MRI检查或染色体检查,经生后随访或尸检证实超声检查结果。计算超声和MRI诊断胎儿脑中线结构异常的阳性预测值,采用卡方检验进行统计学分析。结果产前超声诊断胎儿脑中线结构异常178例,其中前脑无裂畸形27例,胼胝体发育不全53例,单纯透明隔腔缺如2例．Dandy-Walker畸形9例,小脑蚓部发育不良14例,巨大枕大池73例。178例胎儿失访9例．经生后随访或尸检证实的169例胎儿中,真阳性数为145例;178例胎儿中共有73例接受MRI检查,阳性60例,其中真阳性数为53例;超声和MRI诊断胎儿脑中线结构异常的阳性预测值分别为85．8％及88-3％．二者间差异无统计学意义（P〉0．05）。结论超声检查安全有效．方便省时,对胎儿脑中线结构异常确诊率较高．是产前筛查胎儿脑中线结构异常的可靠方法。     

Germline mosaicism in Rett syndrome identified by prenatal diagnosis

Rett syndrome is an X-linked neurodevelopmental dominant disorder that affects almost exclusively girls. The vast majority of cases are sporadic and are caused by de novo mutations in the MECP2 gene, located in Xq28. Only few familial cases have been reported: in four cases, the mother was an asymptomatic carrier and in other four cases, the germline mosaicism in the mother was postulated. Owing to the above reported cases of germline mosaicism, we decided to offer prenatal diagnosis to all expectant mothers with a Rett daughter despite the absence of the causative mutation in parents' blood. We describe here the outcome of the first nine cases of prenatal diagnosis followed by our center. In eight cases, the fetus did not carry the mutation. In one case, the female fetus did carry the same mutation of the affected sister. The couple decided to interrupt the pregnancy and to devolve fetal tissues for research purposes. Our results indicate that prenatal diagnosis should be proposed to all couples with a Rett daughter, even when the mutation is apparently de novo. Moreover, one positive prenatal test among the first nine cases indicates that germline mosaicism may be seriously considered for the assessment of recurrence risk during genetic counseling.     

光谱核型分析技术在染色体异常诊断中的应用

目的建立稳定的光谱核型分析技术,并评价其在染色体异常诊断中的应用价值。方法应用光谱核型分析技术对16例外周血和1例羊水细胞染色体样本进行诊断,并与G-显带诊断结果进行比较。结果所建立的光谱核型分析技术不但成功地对全部15例G-显带诊断结果为正常或平衡易位的样本进行了正确诊断,而且对G-显带无法识别的1例外周血样本的衍生染色体片段和1例羊水样本的标记染色体亦明确了来源。结论光谱核型分析技术对染色体异常的诊断具有很高的敏感性和特异性,并且在明确传统核型分析技术不能分析的标记染色体或衍生染色体片段的来源方面具有重要应用价值。     

20-year experience on prenatal diagnosis in a reference university medical genetics center in Turkey

Background/aimAlthough cutting edge procedures such as cell-free fetal DNA isolation from maternal blood are now available, invasive prenatal tests are still being used extensively for prenatal diagnosis. The study aims to evaluate the demographic data, indications, and cytogenetic results of 9297 results of patients who underwent prenatal invasive testing for genetic analysis that were referred for the last 20 years in a University Medical Genetics Center.Materials and methodsThe records of 8363 amniocenteses, 626 chorionic villus, and 308 cordocenteses samples were retrospectively evaluated and analyzed regarding referral reasons, indications and their cytogenetic results. The total numbers and the percentages of each group were recorded; Chi-square and logistic regression analyses were performed to give the statistical likelihood of different events. ResultsThe number of referrals decreased significantly after 2009. Risk of having trisomy 21 as well as trisomy 13 and 18 significantly increased in parallel with advanced maternal age. When the 21–25 age group was compared to the older age groups in terms of having a trisomy 21 pregnancy, the risk doubled in the 36–40, 5 times higher in 41–45 and 10-fold in 46–50 age groups. No significant linear correlation between maternal serum screening test results and trisomy 21 was found, however the difference between the pregnancies whom cut-off value above and below 1/250 in maternal serum screening test were significant.ConclusionThese data have provided useful information on the frequency of referrals to the reference genetics department, and the feasibility of genetic services. By reviewing the indications and their corresponding results, we can offer invaluable insights that will be useful in genetic counseling and also in the development of more effective genetic strategies.     

Non-mosaic trisomy 20 in amniotic fluid cultures with minor anomalies in the fetus

A non-mosaic trisomy 20 was discovered in all cells in two separate cultures from an age-related genetic amniocentesis. Karyotypes of cells obtained via amniocentesis at the time of termination and of cells cultured from the placenta gave the same unambiguous results. However, the fetus, under macro- and microscopic analysis, showed only two minor anomalies: left simian crease and low-set ears. These findings are more suggestive of a normal or at most mosaic trisomy 20 state. The significance of this finding for prenatal diagnosis is discussed.