Frequencies of chromosomal abnormalities at amniocentesis: Over 20 years of cytogenetic analyses in one laboratory

Prenatal diagnosis of chromosomal disorders has been performed for more than 20 years, mainly for advanced maternal age. Chromosomal abnormality rates derived from second trimester amniocentesis have mainly come from a collection of small-scale studies from North America and Western Europe. Accurate risk estimates for chromosomal abnormalities are important tools for the physician or obstetrician who would need to make referrals to a prenatal genetic center. This paper presents amniocentesis rates of clinically significant cytogenetic abnormalities for various indications, including advanced maternal age, previous chromosomal abnormality, parental structural rearrangement and a family history of aneuploidy as defined in the text. These data come from a Canadian prenatal diagnosis laboratory with more than 20 years experience in second trimester cytogenetic analysis. They show that the overall frequency of chromosomal abnormalities for advanced maternal age (⩾35 years) is 1.79%. In this group, 21% of all abnormalities are structural rearrangements (including markers) and less than half of all abnormalities are trisomy 21. The advanced maternal age specific risk of aneuploidies at second trimester is 1.24%. Recurrence risk for aneuploidy after a previous one is 1.29%. However, it is much higher (4.84%) for women of ⩾35 years. When a parent's brother, sister, nephew or niece is affected, the risk of occurrence of aneuploidies (0.24%) is not elevated. When there is a balanced translocation in one of the parents, the overall risk is 10.2% for unbalanced translocations and 37.3% for balanced translocations. Am. J. Med. Genet. 82:149–154, 1999. © 1999 Wiley-Liss, Inc.     

Do parental perceptions and motivations towards genetic testing and prenatal diagnosis for deafness vary in different cultures?

Surveys of attitudes of individuals with deafness and their families towards genetic testing or prenatal diagnosis have mostly been carried out in the West. It is expected that the perceptions and attitudes would vary amongst persons of different cultures and economic background. There is little information on the prevailing attitudes for genetic testing and prenatal diagnosis for deafness in developing countries. Therefore, this study evaluates the motivations of Indian people with inherited hearing loss towards such testing. Twenty‐eight families with history of congenital hearing loss (23 hearing parents with child/family member with deafness, 4 couples with both partners having deafness and 1 parent and child with deafness) participated in a semi‐structured survey investigating their interest, attitudes, and intentions for using genetic and prenatal testing for deafness. Participants opinioned that proper management and care of individuals with deafness were handicapped by limited rehabilitation facilities with significant financial and social burden. Nineteen (68%) opted for genetic testing. Twenty‐six (93%) expressed high interest in prenatal diagnosis, while 19 (73%) would consider termination of an affected fetus. Three hearing couples, in whom the causative mutations were identified, opted for prenatal diagnosis. On testing, all the three fetuses were affected and the hearing parents elected to terminate the pregnancies. This study provides an insight into the contrasting perceptions towards hearing disability in India and its influence on the desirability of genetic testing and prenatal diagnosis. © 2012 Wiley Periodicals, Inc.     

Prenatal ultrasonographic findings of dominant polycystic kidney disease and postnatal renal evolution

Autosomal dominant polycystic kidney disease (ADPKD) is a relatively common genetic disorder, and its prenatal diagnosis has been reported with increasing frequency. Nevertheless, no data are available on the significance of prenatal ultrasound (US) patterns in predicting postnatal renal function and outcome. We report on one case of ADPKD diagnosed prenatally by US, and on two cases diagnosed immediately after birth, with different prenatal US and renal outcomes. Data on prenatal US findings and postnatal renal evolution are scanty and largely incomplete. Apparently, none of the prenatal findings are consistently different in cases with and without normal postnatal renal function and blood pressure. More complete information on prenatal US findings and postnatal renal evolution is urgently needed. © 1996 Wiley-Liss, Inc.     

Routine prenatal diagnosis of aneuploidy by FISH studies in high‐risk pregnancies

This study is a prospective clinical trial with fluorescent in situ hybridization (FISH) as a “routine” test for prenatal detection of the most common aneuploidies in high‐risk pregnancies. Since April 1996, FISH studies with multicolor, commercially available, specific probes for chromosomes 13, 18, 21, X, and Y have been routinely performed in our cytogenetic laboratory on uncultured chorionic villous samplings (CVS), amniotic fluid samples, or fetal blood obtained by cordocentesis from patients with major or minor fetal anomalies detected by ultrasonography. Among the 4,193 prenatal samples analyzed between April 1996 and June 1998, routine FISH studies were ordered by the referring physicians on 301 (7.2%) cases. Aneuploidies were detected in 32 (10.6%) samples. Fourteen trisomy‐21, 10 trisomy‐18, 3 trisomy‐13, 4 monosomies of X, and 1 case of triploidy were diagnosed by FISH. All 1,505 hybridizations were informative, and all 301 results were available and reported to the referring physicians in 24–48 hr. All relevant FISH results were confirmed by subsequent cytogenetic analysis. In 10 (3.8%) cases with normal FISH results, the final cytogenetic analysis revealed abnormal chromosomal rearrangements that could not be detected by the routine FISH studies. We conclude that rapid FISH analysis of interphase, uncultured fetal cells is an accurate and very sensitive method for routine prenatal diagnosis of the most common aneuploidies in high‐risk pregnancies. Am. J. Med. Genet. 90:233–238, 2000. © 2000 Wiley‐Liss, Inc.     

Prenatal phenotyping: A community effort to enhance the Human Phenotype Ontology

Technological advances in both genome sequencing and prenatal imaging are increasing our ability to accurately recognize and diagnose Mendelian conditions prenatally. Phenotype-driven early genetic diagnosis of fetal genetic disease can help to strategize treatment options and clinical preventive measures during the perinatal period, to plan in utero therapies, and to inform parental decision-making. Fetal phenotypes of genetic diseases are often unique and at present are not well understood; more comprehensive knowledge about prenatal phenotypes and computational resources have an enormous potential to improve diagnostics and translational research. The Human Phenotype Ontology (HPO) has been widely used to support diagnostics and translational research in human genetics. To better support prenatal usage, the HPO consortium conducted a series of workshops with a group of domain experts in a variety of medical specialties, diagnostic techniques, as well as diseases and phenotypes related to prenatal medicine, including perinatal pathology, musculoskeletal anomalies, neurology, medical genetics, hydrops fetalis, craniofacial malformations, cardiology, neonatal-perinatal medicine, fetal medicine, placental pathology, prenatal imaging, and bioinformatics. We expanded the representation of prenatal phenotypes in HPO by adding 95 new phenotype terms under the Abnormality of prenatal development or birth (HP:0001197) grouping term, and revised definitions, synonyms, and disease annotations for most of the 152 terms that existed before the beginning of this effort. The expansion of prenatal phenotypes in HPO will support phenotype-driven prenatal exome and genome sequencing for precision genetic diagnostics of rare diseases to support prenatal care.     

应用多重连接依赖探针扩增技术快速检测胎儿染色体非整倍体异常

目的 探讨多重连接依赖探针扩增(multiplex ligation-dependent probe amplification,MLPA)技术在常见染色体非整倍体异常检测及其在产前诊断中的应用价值.方法 应用MLPA技术检测561份产前诊断样本和20例已知染色体异倍体标本,所有样本均进行常规染色体核型分析,比较MLPA结果和染色体核型分析结果,评价MLPA技术的临床符合率.结果 MLPA技术能够在48 h内出具检测结果,共检测出38例染色体异倍体,包括20例21-三体,10例18-三体,1例13-三体,4例Turner综合征,1例Klinefelter综合征,1例超雄综合征,1例48,XYY,+18双三体综合征.MLPA结果与染色体核型结果一致,检测结果100％准确.在561份产前诊断样本中,有550份样本的MLPA分析结果和细胞染色体核型的结果一致,临床符合率达到98.04％.结论 MLPA技术具有快速、简单、稳定等优点,可检测常见非整倍体异常,能作为产前诊断的可靠方法,具有临床实际应用价值.     

Prenatal course of metaphyseal anadysplasia associated with homozygous mutation in MMP9 identified by exome sequencing

Metaphyseal anadysplasia (MANDP) is a rare autosomal recessive form of skeletal dysplasia characterized by normal length at birth and transitory bowing of the legs. Although several families with MANDP have been reported, homozygous mutations in the matrix metalloproteinase type 9 (MMP9) gene have been described in only one consanguineous family, and thus the pre and postnatal phenotypic spectrum is still obscure. A clinically similar but more severe type is caused by autosomal‐dominant inheritance and is caused by mutations in matrix metalloproteinase type 13 gene (MMP13). Here, we report the prenatal and early postnatal course of two affected sib fetuses with early sonographic evidence of long bone shortening and postnatally no metaphyseal changes. Whole‐exome sequencing revealed homozygous mutation in MMP9 in both fetuses suggesting a diagnosis of MANDP. We propose that MANDP should be considered in pregnancies with early prenatal shortening of the long bones without associated finding of lethal skeletal dysplasias. In addition, the finding of homozygous mutation in non‐consanguineous parents of Jewish‐Caucasus ancestry may suggest unawareness of such relation or the occurrence of a founder mutation in this gene.     

Prenatal diagnosis of micrognathia in 41 fetuses: Retrospective analysis of outcome and genetic etiologies

Fetal micrognathia can be detected early in pregnancy. Prognosis of micrognathia depends on the risk of respiratory distress at birth and on the long‐term risk of intellectual disability. The purpose of this study was to evaluate the long‐term prognosis of fetuses with prenatal diagnosis of micrognathia by estimating the prevalence and the severity of confirmed genetic diagnosis in our cohort. Our retrospective study included 41 fetuses with prenatal diagnosis of micrognathia referred to the multidisciplinary centers for prenatal diagnosis in Nice and Marseille, France, between 2006 and 2016. Fetal micrognathia was associated with cleft palate in 27 cases. A genetic cause was confirmed in 21 cases (67%). A chromosomal abnormality was present in 12 cases, including three copy‐number variations diagnosed by array CGH. Monogenic disorders were identified in nine cases, most often after birth. Fetuses with family history of micrognathia or Pierre Robin sequence had a favorable outcome. Prognosis was good for the fetuses without associated findings and normal chromosomal analysis, with the exception of one case with a postnatal diagnosis of mandibulofacial dysostosis with microcephaly. Prognostic was poor for the fetuses with additional ultrasound anomalies, as only 5 out of 28 children had a good outcome. Prenatal diagnosis of micrognathia is an indicator of a possible fetal pathology justifying multidisciplinary management. Our study confirms the necessity of performing prenatal array CGH. Use of high‐throughput gene sequencing in prenatal period could improve diagnostic performance, prenatal counseling, and adequate postnatal care.     

应用优化荧光原位杂交技术诊断110例羊水间期细胞常见非整倍体

目的 优化现有荧光原位杂交(fluorescence in situ hybridization,FISH)技术,探讨FISH快速产前诊断多种染色体异常的临床应用.方法 改良FISH操作过程中的滴片和杂交液用量,对110例孕妇羊水样本同时进行FISH快速产前诊断和常规细胞培养核型分析.结果 110例羊水样本中,FISH检测出了4例21三体、1例18三体、58例46,XX、47例46,XY,与染色体核型分析的结果一致,符合率100%.结论 国产FISH试剂能快速、准确检测常见的5种染色体数日异常,使用样本量少、价廉.FISH技术可作为经典染色体核型分析的辅助方法,能应用于唐氏血清学高风险孕妇的快速产前诊断.     

Loss‐of‐Function FANCL Mutations Associate with Severe Fanconi Anemia Overlapping the VACTERL Association

The diagnosis of VACTERL syndrome can be elusive, especially in the prenatal life, due to the presence of malformations that overlap those present in other genetic conditions, including the Fanconi anemia (FA). We report on three VACTERL cases within two families, where the two who arrived to be born died shortly after birth due to severe organs’ malformations. The suspicion of VACTERL association was based on prenatal ultrasound assessment and postnatal features. Subsequent chromosome breakage analysis suggested the diagnosis of FA. Finally, by next‐generation sequencing based on the analysis of the exome in one family and of a panel of Fanconi genes in the second one, we identified novel FANCL truncating mutations in both families. We used ectopic expression of wild‐type FANCL to functionally correct the cellular FA phenotype for both mutations. Our study emphasizes that the diagnosis of FA should be considered when VACTERL association is suspected. Furthermore, we show that loss‐of‐function mutations in FANCL result in a severe clinical phenotype characterized by early postnatal death.     

应用变性高效液相色谱技术进行肝豆状核变性的基因突变筛查及产前诊断

目的 探讨变性高效液相色谱(denature high performance liquid chromatography,DHPLC)技术在肝豆状核变性(Wilson's disease,WD)的突变筛查及产前诊断中的临床应用.方法 以6个WD家系中的患者及其父母的DNA为模板,采用PCR技术扩增ATP7B基因的21个外显子及5'非翻译区,PCR产物经DHPLC技术进行突变筛查,对峰型有改变者进行测序验证.在确定了先证者突变类型的基础上,采用相同方法对其中4个家系(1个双胎和3个单胎)进行产前诊断.结果 6例患者中检测出5种已知的致病突变及8种多态类型.患者的父母均为相应突变类型的携带者.产前诊断结果显示,两例妊娠为异常胎儿,其中1例双胎为Arg778Leu/IVS4-1G>C双重杂合子,1例单胎为Ser975Tyr/Pro992Leu双重杂合子,这两对妊娠夫妇选择了终止妊娠.另两例妊娠中,1例为Ser975Tyr杂合子,1例完全正常,他们选择了继续妊娠,出生了表型正常儿.结论 DHPLC在Wilson病的突变检测和产前诊断中有良好的应用前景.     

未培养羊水荧光原位杂交快速检测60例胎儿常见染色体数目异常

目的 应用细菌人工染色体(bacterial artificial chromosome,BAC)克隆自行制备荧光探针,对胎儿常见染色体数目异常(13,18,21,X,Y)行快速产前诊断.方法 利用中国医学遗传学国家重点实验室BAC库中相应染色体特异位点克隆,自行制备荧光探针.经外周血淋巴细胞染色体杂交验证后,用于胎儿未培养羊水的快速荧光原位杂交fluorescence in situ hybridization,FISH)检测,已检测60例羊水标本.结果 所有探针特异性均为100%,杂交成功率为97.86%;FISH结果与常规核型分析一致,检出21三体2例,18三体1例.有两例涉及其它染色体的结构异常未能检出.结论 自制探针用于未培养羊水快速FISH,使用标本量少、快速、简便,可有效检出上述5种染色体的数目异常,但本法不能检出其他染色体的数目异常和结构异常,其应用仍有一定局限性.     

Implementation of high‐resolution SNP arrays in the investigation of fetuses with ultrasound malformations: 5 years of clinical experience

Chromosome microarray analysis (CMA) has proven to be a powerful tool in postnatal patients with intellectual disabilities, and it is increasingly used in prenatal diagnosis. However, its diagnostic capabilities in prenatal diagnosis vary, and clinical experiences have failed to establish a consensus regarding CMA indications, the design and resolution of microarrays, and the notification and interpretation of copy number variations (CNVs). We present our 5 years of clinical experience using whole‐genome high‐resolution single nucleotide polymorphism (SNP) arrays to investigate 446 fetuses that had structural malformations detected with ultrasound but for which standard karyotyping analysis showed normal karyotypes. CMA revealed genomic CNVs in 323 (72.4%) cases and clinically significant CNVs in 11.4% of the fetuses (51/446), including 2 cases of uniparental disomy (UPD) as well as 1 case of cryptic mosaic monosomy of chromosome X. Variants of unknown significance (VOUS) existed in 2.0% of the tested fetuses (9/446). Our results demonstrate the value of whole‐genome high‐resolution SNP arrays in fetuses with congenital malformations and give a higher detection rate of clinically significant genomic imbalance, especially for detecting UPD. Sufficient communication between technicians and genetic counselors, along with parental testing and comparison with data from in‐house or international sources, can significantly reduce VOUS.     

Application of a target array Comparative Genomic Hybridization to prenatal diagnosis

Background  

While conventional G-banded karyotyping still remains a gold standard in prenatal genetic diagnoses, the widespread adoption of array Comparative Genomic Hybridization (array CGH) technology for postnatal genetic diagnoses has led to increasing interest in the use of this same technology for prenatal diagnosis. We have investigated the value of our own designed DNA chip as a prenatal diagnostic tool for detecting submicroscopic deletions/duplications and chromosome aneuploidies.     

荧光原位杂交技术在遗传病诊断中的应用

目的探讨荧光原位杂交(fluorescenceinsituhybridization,FISH)技术在遗传病和产前诊断中的应用价值。方法应用着丝粒探针、特异性序列探针及染色体涂染探针等对36例常规核型分析疑有染色体异常患者的外周血和45例进行产前诊断的孕妇羊水间期细胞或中期分裂相进行FISH检测。结果检出的染色体异常类型有45,X、45,X/46,XX、45,X/46,Xr(X)、46,X,i(Xq)、47,XXY、46,XX,t(4;7)、47,XYY、47,XXX、47,XXY,inv(7)、46,XY,inv(7)、47,XX, 21,同时产前诊断出两例异常胎儿,分别是47,XX, 18和46,XY,der(15)t(Y;15)。结论FISH技术可以准确、快速地诊断各种染色体异常,是传统细胞遗传学的必要补充,可广泛用于遗传病诊断及产前诊断。     

792例血清学高危行无创产前基因检测研究

目的探讨无创产前基因检测联合血清学产前筛查在产前诊断胎儿染色体非整倍体中的应用价值。方法选择2013年5月至2013年12月血清学筛查高危单胎孕妇792例,采用无创产前基因检测的方法评估胎儿染色体非整倍体的患病风险率,对患病风险率提示高危的孕妇进行核型分析以确诊结果。结果检出高风险14例,占调查资料总数1.77%,其中21-三体6例,18-三体3例,性染色体5例,染色体核型分析确认6例21-三体,3例18-三体,1例47,XXY。结论无创产前基因检测的方法能早期、快速、准确、无创地检测21-三体、18-三体,可避免很多不必要的介入性有创检查。无创产前基因检测联合血清学筛查是目前产前筛查最为实用和有效的方法之一。     

Evaluation of prenatal diagnosis of congenital anomalies diagnosable by prenatal ultrasound in patients in neonatal intensive care units of Cali,Colombia

Introduction:

The study aim was to determine the frequency of prenatal ultrasound diagnosis of congenital anomalies in Newborns (NB) with birth defects hospitalized in two Neonatal Intensive Care Units (NICU) of Cali (Colombia) and to identify socio-demographic factors associated with lack of such diagnosis.

Patients and methods:

It was an observational cross-sectional study. NB with congenital defects diagnosable by prenatal ultrasound (CDDPU), who were hospitalized in two neonatal intensive care units (NICU), were included in this study. A format of data collection for mothers, about prenatal ultra-sonographies, socio-demographic data and information on prenatal and definitive diagnosis of their conditions was applied. Multiple logistic and Cox regressions analyses were done.

Results:

173 NB were included, 42.8% of cases had no prenatal diagnosis of CDDPU; among them, 59.5% had no prenatal ultrasound (PNUS). Lack of PNUS was associated with maternal age, 25 to 34 years (Odds Ratio [OR]: 4.41) and 35 to 47 years (OR: 5.24), with low levels of maternal education (OR: 8.70) and with only a PNUS compared to having two or more PNUS (OR: 4.00). Mothers without health insurance tend to be delayed twice the time to access the first PNUS in comparison to mothers with payment health insurance (Hazard Ratio [HR]: 0.51). Among mothers who had PNUS, screening sensitivity of CDDPU after the 19^th gestational week was 79.2%.

Conclusions:

The frequency of prenatal diagnosis is low and is explained by lack of PNUS, or by lack of diagnostic in the PNUS. An association between lack of PNUS and late age pregnancy and low level of maternal education was found. In addition, uninsured mothers tend to delay twice in accessing to the first PNUS in comparison to mothers with health insurance. It is necessary to establish national policies which ensure access to appropriate, timely and good quality prenatal care for all pregnant women in Colombia.     

Counselling following diagnosis of a fetal abnormality: Comparison of different clinical specialists in Mexico

Most geneticists agree that counselling should be nondirective, and studies report that genetic counselling by geneticists is performed largely in a neutral style. However, couples at risk of having a child with a genetic condition may seek the advice of other physicians. The purpose of the present study was to describe the answers of four groups of specialists from Mexico City (internists, pediatricians, obstetricians, and neurologists) regarding how they would counsel a couple when prenatal diagnosis has shown that a fetus is affected by one of 17 different genetic disorders and to analyze the role of several variables in the development of their opinion. Our results show that physicians in these specialties are more likely to counsel directively than neutrally. Other variables did not influence the directiveness. With respect to direction of influence, internists, pediatricians, and neurologists are more likely to counsel terminating affected pregnancies than are obstetricians (P = 0.0002). Similarly, clinicians older than 37 years of age and those reporting that religion is not important to them counsel terminating affected pregnancies (P = 0.005 and P = 0.003, respectively). Physicians' gender and clinical experience with genetic diseases did not show statistically significant differences. Strong consensus among specialists was reached only on terminating pregnancies in anencephaly. A lowered and moderate consensus (51–75% agreement) was reached on continuing pregnancies with cleft lip and plate. A moderate measure of consensus for nondirective counselling was found among obstetricians regarding 14 of the 17 diseases in the study, whereas neurologists expressed a moderate measure of consensus on counselling the termination of pregnancies when the fetus was affected by neurological disorders. Hence, the approach to counselling was related in part to the fetal condition and in part to the clinician's specialty and age and the self-reported importance of religion. The data presented herein may not be representative of all Mexican physicians within the selected specialties; however, it is important to gather their opinions because they are involved in the care and treatment of genetic diseases and may have an important influence on the demand and availability of prenatal diagnosis and abortion. Am. J. Med. Genet. 69:23–28, 1997. © 1997 Wiley-Liss, Inc.     

Hearing from parents: The impact of receiving the diagnosis of Williams syndrome in their child

Healthcare providers often share difficult or life‐altering news with their patients yet this challenging and delicate process is frequently met with dissatisfaction by those receiving this news. Articles and guidelines exist to aid providers in sharing diagnoses such as Down syndrome, but relatively few have focused on rare genetic conditions often diagnosed years after birth. For this reason, we sought to learn about the experience of receiving a diagnosis from parents of children with Williams syndrome. We asked members of the Williams Syndrome Association to complete an anonymous online survey about recollections related to the diagnostic process. Responses, both close‐ended and open‐ended, were received from 600 families across the United States. Analysis revealed a high proportion of families (59.91%) with at least some negative recollections about the experience (and nearly half of those with negative recollections denied recalling anything positive). Factors influencing a more positive overall perception of the experience included receiving written information about Williams syndrome and seeing a genetic counselor. Analysis of open‐ended responses identified additional positive and negative themes; for example, nearly one quarter of respondents expressed a desire to be given hope when receiving the diagnosis. Based on these analyses, we offer several specific recommendations for improving the diagnostic process in the future. © 2013 Wiley Periodicals, Inc.     

160例孕妇羊水地中海贫血基因诊断结果和临床分析

目的回顾性分析160例羊水地中海贫血基因诊断结果及孕妇围产期超声结果,探讨较为合理的产前诊断与干预处理方案。方法在160例有重型地中海贫血遗传风险的胎儿的羊水分别运用gag—PCR法和PCR—RDB法进行产前基因诊断。结果117例夫妇同为α地贫基因携带者孕妇的胎儿中检出正常胎儿38例32．5％（38／117）,α地贫基因携带者57例48．7％（57／117）,地中海贫血水肿胎（Bartg水肿胎）22例18．8％（22／117）。43例夫妇同为β地贫基因携带者孕妇的胎儿中检出正常胎儿16例37．2％（16／43）,13地贫基因携带者15例34．9％（15／43）,B重型胎儿12例27．9％（12／43）。34例重型地贫胎儿均已引产。结论gag—PCR与PCR—RDB在产前羊水基因诊断中占据重要地位,对于无创性超声产前诊断的应用,也起到了重要的诊断和补充作用。