Prenatal diagnosis of trisomy 9

Fetal trisomy 9, especially its nonmosaic form, is a rare chromosomal abnormality and there are only 8 cases reported to have been sonographically detected in the prenatal period. We report a case of nonmosaic fetal trisomy 9, mimicking trisomy 13 on sonographic findings at 32 weeks' gestation. Although the incidence of trisomy 9 is rare, diagnosing trisomy 9 is important because the sonographic features are similar to those of trisomies 13 and 18, and cannot to be identified by routine fluorescencein situ hybridization. Because nonmosaic trisomy 9 is universally lethal, correct diagnosis and appropriate counseling is essential in patient care and clinical management.     

Prenatal diagnosis of a fetus with distal 10q trisomy.

Distal 10q trisomy is a well-defined but rare syndrome. Most cases are diagnosed in infancy or in childhood and rarely include prenatal findings. We present a case of fetal distal 10q trisomy with abnormal prenatal sonographic findings. A 19-year-old primigravida was referred for genetic counselling at 18 gestational weeks because her husband had a familial history of congenital anomalies. Genetic amniocentesis was thus performed and showed fetal distal 10q trisomy (10q24.1-->qter), 46,XX,der(22)t(10;22)(q24.1;p11.2)pat, resulting from paternal t(10;22) reciprocal translocation. Level II ultrasonograms further demonstrated bilateral hydronephrosis, ventricular septal defect and facial dysmorphism ascertained by three-dimensional ultrasound. The pregnancy was terminated at 22 gestational weeks. Post-mortem autopsy confirmed the sonographic findings. We suggest that abnormal prenatal sonographic findings such as cardio-vascular, renal and facial malformations should alert cytogeneticists to search for subtle chromosomal abnormalities.     

Sonographic detection of fetuses with trisomies 13 and 18: accuracy and limitations

Nine fetuses having trisomy 13 and 15 fetuses with trisomy 18 were diagnosed by cytogenetic studies and also underwent a sonogram between 15 and 40 weeks. All nine fetuses with trisomy 13 had been prospectively identified as having sonographic findings suggestive of trisomy 13. Twelve of the 15 fetuses with trisomy 18 had sonographic abnormalities compatible with trisomy 18. Findings included abnormalities of the face and head, extremities, and diaphragmatic hernia. This report examines criteria for the ultrasound diagnosis of trisomies 13 and 18 and describes the accuracy of prenatal sonography for these diagnoses.     

Sonographic features of trisomy 18 at midpregnancy

OBJECTIVE: To evaluate the sonographic characteristics of the fetuses with trisomy 18 at 16-22 weeks of gestation. METHODS: The subjects were recruited from pregnant women undergoing prenatal sonographic examinations at 16-22 weeks of gestation and subsequently proven to be trisomy 18. The results of ultrasound findings were retrospectively reviewed in 25 cases with chromosomes which were confirmed as trisomy 18. RESULTS: All cases had at least one abnormal sonographic finding. There was only one case that had no structural abnormality, but fetal growth restriction was documented. The common sonographic findings included fetal growth restriction, choroid plexus cysts, cardiac anomalies, clenched hand, omphalocele and cleft lip. Fetal growth restriction was the most common finding demonstrated in nearly half of all cases. Other less common findings were diaphragmatic hernia, abnormal head shape, polyhydramnios, single umbilical artery. CONCLUSION: Nearly all fetuses with trisomy 18 had characteristic sonographic patterns of abnormalities demonstrated at midpregnancy. Detailed ultrasound at midpregnancy could effectively screen fetuses with trisomy 18 for further genetic testing.     

9例18三体综合征胎儿的产前诊断

目的探讨利用孕妇血清筛查和胎儿超声筛查进行18三体综合征胎儿产前诊断的有效性。方法对36例首诊主诉为产前筛查胎儿18三体高危、92例首诊主诉为胎儿超声有异常发现的孕18~32周孕妇共128例，进行羊膜腔穿刺羊水细胞培养、或脐血管穿刺脐血细胞培养染色体分析。结果128例胎儿核型中，9例为18三体综合征，2例为其它染色体异常，染色体异常发现率为8．59％（11／128）。首诊主诉为18三体高危发现18三体4例，异常发现率11．11％（4／36）；首诊主诉胎儿超声异常发现18三体5例，其它染色体异常2例，异常发现率7．61％，其中2例18三体合并有筛查高危和超声异常。结论孕妇血清生化指标筛查结合胎儿超声检查是产前检出18三体胎儿的有效筛查手段。     

Prenatal sonographic findings in 207 fetuses with trisomy 21

OBJECTIVE: The objective was to evaluate the contribution of second trimester ultrasound examination to the prenatal diagnosis of trisomy 21 in 207 fetuses with this aneuploidy. The type and frequency of abnormal sonographic findings were determined. Possible multiple malformation patterns, characteristic of trisomy 21 were sought. STUDY DESIGN: Singleton fetuses that had prenatal sonography during the second trimester, then underwent cytogenetic evaluation in our institution, made up the study population. The sonographic findings of 207 fetuses with trisomy 21 were analyzed. RESULTS: Between 1990 and 2004, fetal karyotyping was performed in 22,150 patients for different indications. An abnormal karyotype was diagnosed in 514 cases (2.3%); among them 207 fetuses with trisomy 21 were detected (40.3%). Abnormal sonography was seen in 63.8% of the cases. Structural anomalies were detected in 28.5% of the trisomy 21 fetuses, among them cardiac defects (15.9%), central nervous system anomalies (14.5%), and cystic hygromas (6.8%) were the most common. Of the minor markers, increased nuchal translucency (28%), pyelectasis (20.3%), and shorter extremities (8.7%) were common findings. CONCLUSIONS: Appropriate diagnosis of structural anomalies, looking for relatively easily detectable minor markers and incorporating fetal echocardiography into the second trimester sonographic protocol, may increase the contribution of mid-trimester ultrasound examination to diagnosing trisomy 21.     

Pseudocyst of the umbilical cord: prenatal sonographic appearance and clinical significance

OBJECTIVE: To assess the clinical significance of umbilical cord pseudocysts detected prenatally by sonography. METHODS: The prenatal sonographic findings, karyotype, and perinatal outcome in 13 fetuses with umbilical cord pseudocysts were reviewed retrospectively. RESULTS: Umbilical cord pseudocysts were diagnosed at a median gestation of 27 weeks (range 15-37). Pseudocysts were single in eight cases with cyst diameters ranging from 20 to 50 mm, and double in one case. In the remaining four cases, multiple small cystic masses measuring less than 8 mm were identified. Additional sonographic findings were noted in 11 cases; ten of these fetuses had prenatal karyotyping, which showed trisomy 18 in five cases, trisomy 13 in one case, and a 46,XX, inv ins(18;21) complement in one case. Among the seven chromosomally abnormal fetuses, umbilical cord pseudocysts were multiple in four fetuses and single in three. All chromosomally abnormal fetuses and two euploid fetuses with associated structural defects died in utero or in the neonatal period. There were no perinatal complications in either of the fetuses with isolated pseudocysts. CONCLUSION: The prenatal sonographic appearance of umbilical cord pseudocysts varied widely. These umbilical cord cystic masses were associated strongly with chromosomal disorders and structural defects, regardless of their sonographic appearance in utero.     

The prenatal diagnosis of Pierre-Robin sequence.

The purpose of this study was to evaluate the spectrum of prenatal sonographic and chromosomal findings, associated anomalies and perinatal and neonatal outcomes in cases with Pierre-Robin sequence. All cases (20) with Pierre Robin sequence, who were born at China Medical College Hospital between 1990 and 1997, were included and analysed in this series. 12 pregnancies (60 per cent) were complicated by polyhydramnios and 9 (45 per cent) were combined with cleft palate. Four cases (20 per cent) with cardiac anomalies were also observed. Two fetuses (10 per cent) had abnormal karyotyping (one trisomy 21, one trisomy 18). All fetuses were delivered at or near term. Male deviation was observed in cases with isolated Pierre-Robin sequence or combined mild anomalies (male female ratio: 13:3). Two neonatal mortalities and three with mental retardation were observed. This investigation provides a basis for counselling patients with fetal micrognathia or neonatal Pierre-Robin sequence. The main prenatal sonographic findings of Pierre-Robin sequence are micrognathia, polyhydramnios and cleft palate. In cases of polyhydramnios, sonographic examination of the facial profile and palate are recommended. After the finding of polyhydramnios, micrognathia, and even cleft palate, clinicians should be aware of the possibility of neonatal Pierre-Robin sequence. Cardiac evaluation and karyotyping is also recommended.     

超声在18-三体综合征产前诊断中的意义

目的 探讨超声在18-三体综合征产前诊断中的意义。方法 对我院1年来经羊水细胞或脐血细胞染色体核型分析确诊为18-三体综合征的5例胎儿超声影像资料进行回顾性分析，评估超声在产前对18-三体综合征胎儿检出的临床价值。结果 5例18-三体综合征患儿至少存在1种以上的超声异常声像。结论 妊娠期超声可检测到18-三体胎儿在形态结构上发生的异常，结合羊水或脐血染色体核型诊断，对于提高18-三体综合征胎儿的产前诊断率，降低严重染色体病缺陷患儿的出生率具有重要意义。     

Prenatal diagnosis and genetic analysis of double trisomy 48,XXX,+18

Prenatal diagnosis of simultaneous occurrence of double trisomy involving chromosomes 18 and X is extremely rare. We report on the prenatal diagnosis, genetic analysis and clinical manifestations of a fetus with both trisomy 18 and trisomy X. A 26-year-old, para 1 woman was referred for genetic counselling at 36 weeks' gestation with the sonographic findings of intrauterine growth retardation (IUGR), polyhydramnios, ventricular septal defect, and an enlarged cisterna magna. Both cordocentesis and amniocentesis revealed a consistent karyotype of 48,XXX,+18. Quantitative fluorescent polymerase chain reaction using polymorphic small tandem repeat markers specific for chromosomes 18 and X rapidly determined that both aneuploidies arose as a result of non-disjunction in maternal meiosis II. Our case shows that two non-disjunction events can occur not only in the same parent, but also in the same cell division. Our case also shows that double trisomy, 48,XXX,+18, can demonstrate an enlarged cisterna magna, IUGR and polyhydramnios in prenatal ultrasound.     

Prenatal diagnosis of the Dandy-Walker malformation and ventriculomegaly associated with partial trisomy 9p and distal 12p deletion

OBJECTIVES: To present the prenatal diagnosis and perinatal findings of partial trisomy 9p and distal 12p deletion. METHODS AND RESULTS: Amniocentesis was performed at 17 gestational weeks due to a balanced reciprocal translocation t(9;12)(p11.2;p13.3) in the mother. The father's karyotype was normal. The family had a 5-year-old daughter with a Dandy-Walker malformation and a trisomy 9p syndrome. Cytogenetic analysis of the cultured amniotic fluid cells revealed a 46,XY,der(12)t(9;12)(p11.2;p13.3)mat karyotype with partial monosomy 12p(12pter-->p13.3) and partial trisomy 9p(9pter-->p11.2). Sonographic examination of the fetal brain and skull showed bilateral ventriculomegaly, brachycephaly and a Dandy-Walker malformation with an enlarged cisterna magna and absence of the cerebellar vermis. The pregnancy was terminated subsequently. At autopsy, the proband manifested agenesis of the cerebellar vermis and a typical trisomy 9p phenotype. CONCLUSION: Fetuses with partial trisomy 9p(9pter-->p11.2) may present a Dandy-Walker malformation and ventriculomegaly on prenatal ultrasound in the second trimester. A dosage effect of genes located on 9pter-->p11.2 may be associated with the abnormal development of the central nervous system in patients with partial or complete trisomy 9.     

Trisomy 21. Second-trimester ultrasound

Not every aspect of sonographic examination reveals karyotypic abnormalities. Ultrasound examination of a fetus with trisomy 21 generally reveals normal amniotic fluid, normal placentation, and normal fetal growth. In addition, other chromosomal abnormalities have many of the same sonographic findings as Down syndrome, and many findings have a large overlap with phenotypically normal fetuses. The importance of second-trimester ultrasound screening for Down syndrome has remained great because of its ease of use and relative effectiveness. Trained sonographers can adjust the relative risk for trisomy 21 and alter the need for genetic amniocentesis. It is important that parents understand the limitations of a screening test and the risks and benefits of possible subsequent confirmatory testing. If a major structural abnormality is identified on ultrasound, karyotype determination should be considered. Nuchal thickness in the first or second trimester remains the most clinically useful marker for trisomy 21. The predictive value of all the markers depends on the population studied and can be modified by a host of biochemical markers and historical factors. If fetal karyotype analysis could be performed without sampling through the uterus, prenatal diagnosis could be offered to all pregnant women, and screening would be unnecessary. Despite its limitations, ultrasound will have an important role in prenatal diagnosis at least until isolating and testing fetal cells from maternal blood or other sources becomes practical and widely available. Whether used alone or in conjunction with additional biochemical or molecular serum markers, ultrasound is an important and powerful tool in prenatal genetic evaluation.     

Second-trimester diagnosis of complete trisomy 9 associated with abnormal maternal serum screen results, open sacral spina bifida and congenital diaphragmatic hernia, and review of the literature

OBJECTIVES: To present the prenatal diagnosis of complete trisomy 9 and to review the literature CASE: A 25-year-old primigravida woman was referred for amniocentesis at 19 weeks' gestation because of abnormal maternal screen results showing an elevated maternal serum alpha-fetoprotein (MSAFP) level and a low maternal serum free beta-human chorionic gonadotrophin (MSfreebeta-hCG) level. RESULTS: Genetic amniocentesis revealed a karyotype of 47,XX,+9 in the amniocytes and an elevated amniotic fluid AFP level. Ultrasonography demonstrated intrauterine growth restriction, left congenital diaphragmatic hernia, fetal ascites, a sacral spina bifida, a horseshoe kidney, and absence of amniotic fluid. Ultrafast magnetic resonance imaging scans further depicted detailed anatomical configurations of the major congenital malformations. The pregnancy was terminated subsequently. The proband postnatally manifested characteristic facial dysmorphism, limb deformities, and an open sacral spina bifida with myelomeningocele. Cytogenetic analysis of the skin fibroblasts revealed a karyotype of 47,XX,+9. Molecular studies of various uncultured fetal tissues using microsatellite markers confirmed a diagnosis of complete trisomy 9 resulting from a meiotic I nondisjunction error of maternal origin. CONCLUSION: Complete trisomy 9 can be identified prenatally with advanced maternal age, sonographically detected fetal structural abnormalities, and abnormal maternal serum screen results. Fetuses with complete trisomy 9 may be associated with congenital diaphragmatic hernia, an open sacral spina bifida, elevated MSAFP, and low MSfreebeta-hCG. We suggest detailed prenatal imaging investigations and genetic analyses of multiple fetal tissues when a prenatal diagnosis of trisomy 9 is made.     

Latent class analysis applied to patterns of fetal sonographic abnormalities: definition of phenotypes associated with aneuploidy.

The aim of the present study was to generate different latent variables that classify the major chromosome aneuploidies using frequency and patterns of fetal sonographic abnormalities in a large database. A total of 1867 fetuses with sonographic abnormalities recorded in a database at New England Medical Center from January 1995 to March 1998 were available for the statistical analysis. Included within this group were 61 aneuploid fetuses, including 11 with 45,X, 30 with trisomy 21, 14 with trisomy 18 and 6 with trisomy 13, 40 structural malformations and/or sonographic markers were detected in these 61 aneuploid fetuses. The ability of malformations and sonographic markers to generate different groups of phenotypes was evaluated by means of latent class analysis, using the 61 affected cases. Four different classes were generated with the hypothetical assumption that each of them could satisfactorily identify a respective fetal aneuploidy represented in the study group. Among 40 fetal malformations and/or sonographic markers, the most important findings in generating specific karyotypic groups were cystic hygroma (class 1), duodenal atresia (class 2), holoprosencephaly (class 3) and omphalocele (class 4), respectively. Accuracy of the classification was 72 per cent for Turner syndrome (class 1), 74 per cent for Down syndrome (classes 1 and 2), 88 per cent for trisomy 13 (class 3) and 93 per cent for trisomy 18. The frequency of associated malformations detected sonographically can help to define a phenotype that is likely to be representative of a specific aneuploidy. Before the definitive karyotype is available or, in cases in which patients refuse an invasive prenatal diagnostic procedure, this may improve antenatal clinical management.     

Partial trisomy 20p resulting from recombination of a maternal pericentric inversion: case report of a prenatal diagnosis by chorionic villus sampling

We report a case of prenatal diagnosis of trisomy 20p resulting from a maternal pericentric inversion. The diagnosis was confirmed on both chorionic villi and amniotic cells. This case underlines the fact that prenatal ultrasound diagnosis of this structural anomaly is difficult. The only early sonographic feature was increased nuchal translucency.     

Sonographic measurement of the fetal iliac angle in trisomy 21, 18 and 13

OBJECTIVE: To determine whether iliac wing angle measurement in second trimester fetuses is a useful sonographic marker for the detection of trisomy 21, 18 and 13. METHODS: During the period between September 1998 and September 2001, 406 fetal iliac angle measurements were performed in women in the second trimester of their pregnancies. The iliac angle measurements in fetuses with trisomy 21 (n = 25), trisomy 18 (n = 10) and trisomy 13 (n = 5) were compared with iliac angle measurement in fetuses with normal karyotypes (n = 333). RESULTS: The mean iliac wing angle in the fetuses with trisomy 21 was 92.67 and 79.35 degrees and 74 degrees in fetuses with trisomy 18 and 13 (the mean iliac wing angle in the healthy fetuses was 70.09 degrees ). CONCLUSION: The proven larger iliac wing angle in neonates with Down's syndrome can be demonstrated sonographically during the pregnancy, especially during the second trimester, and may be useful in prenatal screening of trisomy 21. The sonographic measurement of the fetal iliac angle cannot be used as a marker for trisomy 18 and 13. We have shown that fetuses with trisomy 18 and 13, on average, have iliac angles only a few degrees larger than healthy fetuses.     

Correlation of prenatal ultrasound diagnosis and pathologic findings in fetuses with trisomy 13

OBJECTIVES: This study was conducted to compare the prenatal ultrasound findings and postmortem pathologic findings of fetuses with trisomy 13. METHODS: Of 22 150 fetal chromosome analyses, 28 fetuses with trisomy 13 were diagnosed between 1990 and 2004. Findings of second-trimester sonography and subsequent fetal autopsy were compared by organ system, and their correlation was assigned to one of three categories based on the degree of agreement. RESULTS: Of the total of 79 abnormalities that were found on autopsy, prenatal sonography showed 48 (60.8%). The agreement was more than 75% of all abnormalities of these systems: central nervous system (CNS) (76.5%), facial abnormalities (76.5%), urinary system (81.8%) and fetal hydrops (100%), whereas the sensitivity of sonography was lower in these organ systems: heart (53.3%), extremities (12.5%) and abdominal abnormalities (33.3%). In 39.2% of the cases, autopsy findings were not detected by sonography. These additional findings at autopsy involved mainly three organ systems: heart, face and extremities. Some ultrasound findings (n = 17) were not verified at autopsy; most of them were quantitative markers (mild ventriculomegaly, mild pyelectasis). CONCLUSION: Our results indicate that thorough sonographic examination of the fetal face (including ears) and extremities (including hands and feet) with an extensive use of fetal echocardiography may increase the sensitivity of prenatal sonography in detecting trisomy 13.     

Prenatal diagnosis of complete sole trisomy 1q.

The prenatal diagnosis of a complete trisomy of the long arm of chromosome 1 is reported. Major ultrasound findings included: nuchal thickening, bi-temporal narrowing, a single choroid plexus cyst, and mild ventriculomegaly. There was a mass in the chest and abdomen, pleural effusion, ascites and a hyperechoic bowel. Skin edema was present. The fetus died at 26 weeks' gestation. A literature review is presented of 17 de novo and two inherited cases with only trisomy 1q. Of note is the fact that 3/5 prenatally detected 1q trisomies have teratomas. A review of the literature reveals a dismal outcome for trisomy 1q cases if the duplication involves bands 1q25-->q32.     

产前超声指标评分法对胎儿18三体综合征的诊断价值

目的 探讨产前超声指标评分法对胎儿18三体综合征的诊断价值.方法 采用前瞻性方法对2004年1月至2009年12月在中山大学附属第一医院行产前超声筛查孕妇中,发现胎儿结构或软指标异常者行胎儿染色体核型检查,根据胎儿染色体核型分析结果,分为18三体组和非18三体组.对两组胎儿任一异常超声指标进行单因素logistic回归分析,分别计算各超声指标的阳性似然比(+LR).+ LR≥200的超声指标赋值3分,100≤+LR ＜200的超声指标赋值2分,+LR＜100的超声指标赋值1分.根据受试者工作特性( ROC)曲线,确定最佳诊断界值.结果 (1)符合入选标准孕妇共26 545例,产前超声检查可疑胎儿畸形或有超声软指标异常并接受胎儿染色体检查者共4044例,其中21三体93例,18三体59例,13三体19例,其他类型染色体异常134例,正常核型3739例.22 501例胎儿产前超声检查无异常,3985例胎儿出生后随访其结局也无异常,共计26 486例胎儿为非18三体组,59例18三体胎儿为18三体组.(2)18三体组59例胎儿均有2种及以上超声提示的结构异常,其中最常见为肢体异常(85％,50/59),其次是心脏畸形(83％,49/59)和中枢神经系统异常(75％,44/59).肢体异常中以重叠指最常见,心脏畸形中室间隔缺损最多见,中枢神经系统畸形中最常见为“草莓头”型.(3)经logistic回归分析,所有超声异常指标中可进入回归方程的是脉络膜囊肿、“草莓头”型、后颅窝池增宽、前脑无裂畸形、耳低置、室间隔缺损、左心发育不良综合征等16项,按照此16项超声指标的+LR值分别得出不同分值.(4)18三体组和非18三体组产前超声评分1分值分别为2％ (1/59)和2.549％(675/26 486),4分值分别为9％( 5/59)和0.215％ (57/26486),9分值分别为10％( 6/59)和0.004％( 1/26 486),10～16分值分别为32％ (19/59)和0.(5)以不同总评分值为超声诊断18三体征的截断值,计算出各分值的敏感度和特异度,ROC曲线下面积为0.999.以总评分4分为最佳诊断值,诊断18三体征的敏感度为0.966,特异度为0.997.结论 超声指标评分法对18三体综合征具有较好的诊断价值,以4分作为诊断18三体综合征截断值其诊断效价最高.