Mosaic tetrasomy 9p at amniocentesis: Prenatal diagnosis,molecular cytogenetic characterization,and literature review

ObjectiveThis study was aimed at prenatal diagnosis of mosaic tetrasomy 9p and reviewing the literature.Materials and methodsA 37-year-old woman underwent amniocentesis at 20 weeks' gestation because of advanced maternal age and fetal ascites. Cytogenetic analysis of cultured amniocytes revealed 21.4% (6/28 colonies) mosaicism for a supernumerary i(9p). Repeat amniocentesis was performed at 23 weeks' gestation. Array comparative genomic hybridization, interphase fluorescence in situ hybridization, and quantitative fluorescent polymerase chain reaction were applied to uncultured amniocytes, and conventional cytogenetic analysis was applied to cultured amniocytes.ResultsArray comparative genomic hybridization analysis of uncultured amniocytes detected a genomic gain at 9p24.3–9q21.11. Interphase fluorescence in situ hybridization analysis of uncultured amniocytes using a 9p24.3-specific probe RP11-31F19 (spectrum red) showed four red signals in 47.1% (49/104 cells) in uncultured amniocytes. Cytogenetic analysis of cultured amniocytes revealed a karyotype of 47,XX, +idic(9)(pter→q21.11::q21.11→pter)[4]/46,XX[20] and 16.7% (4/24 colonies) mosaicism for tetrasomy 9p. Quantitative fluorescent polymerase chain reaction confirmed a maternal origin of tetrasomy 9p. The pregnancy was terminated, and a malformed fetus was delivered with hydrops fetalis and facial dysmorphism. The fetal blood cells had 32.5% (13/40 cells) mosaicism for tetrasomy 9p.ConclusionMosaic tetrasomy 9p at amniocentesis can be associated with fetal ascites and hydrops fetalis. The mosaic level of tetrasomy 9p may decrease after long-term tissue culture in amniocytes in case of mosaic tetrasomy 9p.     

Prenatal diagnosis of a familial 9p12 amplification inherited from a father carrier

ObjectiveWe present prenatal diagnosis of a familial 9p12 amplification inherited from a father carrier.Case reportA 38-year-old, gravida 3, para 2, woman underwent amniocentesis at 17 weeks of gestation because of advanced maternal age. Amniocentesis revealed a heteromorphic variant of chromosome 9 with a 9p12 amplification on G-band preparations, but it was negative on C-band preparations. Cytogenetic analysis of the parents revealed that the phenotypically normal father carried the same euchromatic 9p + polymorphism. Array comparative genomic hybridization analysis on the DNA extracted from the father's blood revealed no genomic imbalance. At 37 weeks of gestation, a healthy 2760-g female baby was delivered with no phenotypic abnormality. She was doing well at age one year during follow-up.ConclusionPrenatal diagnosis of a 9p + variant can be a euchromatic chromosome variant of a familial 9p12 amplification without phenotypic consequences.     

Prenatal diagnosis of de novo isochromosome 4p with an unbalanced t(4;9) translocation in a fetus with congenital anomalies: A case report and literature review

ObjectiveWe present the first case of prenatally diagnosed isochromosome 4p with whole 4q arm translocating to chromosome 9p23 and review the literature.Case ReportA 26-year-old woman underwent amniocentesis at 25 weeks of gestation because of an abnormal ultrasound examination. Routine chromosome analysis on cultured amniocytes showed a karyotype of 46,XX, ?idic(4)(q11),der(9)t(4;9)(q11;p23). Single nucleotide polymorphism (SNP) array analysis on uncultured amniocytes detected two copy number variations (CNVs): arr [GRCh37] 4p16.3p11(68345-49089361) × 3; arr [GRCh37] 9p24.3p23(208454-10039391) × 1. The karyotypes of the parents were normal, indicating that the chromosomal rearrangement was de novo. According to the fetal-parent trios SNP analysis, both the abnormal chromosomes were originated from the father. The pregnancy was terminated at 30 weeks of gestation, and a malformed fetus was delivered with dysmorphic craniofacial, short neck, wide-spaced nipples and rocker-bottom feet.ConclusionThe combined application of traditional cytogenetic technology and molecular diagnosis technology in prenatal diagnosis helps identify genetic components and the origin of isochromosome, which enable clinicians to precisely predict the fetal prognosis and provide accurate genetic counselling and fertility guidance.     

Prenatal diagnosis of a case of tetrasomy 9p

A male fetus with tetrasomy 9p [47,XY, + i(9p)] is presented. The cytogenetic interpretation of the marker chromosome was confirmed by assessing the activity of the enzyme galactose I-phosphate uridyl transferase. The clinical findings of the case show features in common with previously reported cases.     

Prenatal diagnosis and molecular cytogenetic characterization of low-level mosaicism for tetrasomy 18p at amniocentesis in a pregnancy with a favorable outcome

Objective

We present prenatal diagnosis of low-level mosaicism for tetrasomy 18p at amniocentesis in a pregnancy with a favorable outcome.

Prenatal diagnosis of a fetus with mosaic ring chromosome 13: Case report and review of the literature

ObjectiveTo diagnose the ring chromosome 13 (r(13)) in a fetus, and analyze the genotype–phenotype correlation.Case reportA 26-year-old woman who was second pregnancy, underwent amniocentesis at 18 weeks of gestation because of the increased nuchal translucency (NT). Prenatal ultrasound showed the NT thickness was 3.5 mm at 12⁺¹ weeks of gestation and nuchal fold (NF) was 6.1 mm at 18 weeks of gestation, and amniotic fluid karyotype analysis revealed mosaic r(13). CMA detected a 16.293 Mb duplication at 13q21.32q31.1 and 31.303 Mb deletion at 13q31.1q34.ConclusionR(13) is a very rare chromosomal abnormality. Cytogenetic examination combined with CMA can provide accurate diagnosis and effective information for genetic counseling.     

Prenatal diagnosis and genetic counseling of uniparental disomy

Uniparental disomy (UPD) is the inheritance of both homologous chromosomes from a single parent. Most chromosomes involving UPD have no pathogenic effects. However, abnormal phenotypes in cases with UPD can be mainly caused by disrupting genetic imprinting and by uncovering harmful autosomal recessive mutations. The documented phenotypes of UPD associated with imprinted genes include maternal UPD for chromosomes 7, 11, 14, 15, 16, and 20, and paternal UPD for chromosomes 6, 11, 14, 15, and 20. Prenatal awareness of UPD is important to provide accurate genetic counseling and prenatal UPD test is suggested when abnormal fetal ultrasound with suspicious phenotypes for UPD syndromes caused by genetic imprinting disorders or presence of chromosomal aberrations involving the imprinted chromosomes.     

Partial tetrasomy 18 mosaicism: Pre and postnatal diagnosis of a unique pattern

ObjectiveTo present prenatal diagnosis and cytogenetic characterization of a unique pattern of partial tetrasomy 18 mosaicism.Case reportA 34-year-old woman underwent amniocentesis at 25 weeks of gestation due to anomalies detected in obstetric ultrasound. It revealed a de novo supernumerary partial isochromosome 18 in 11 of 37 metaphases of cultured amniocytes. The karyotype was 47,XX,+idic(18) (q12.3)[11]/46,XX[26]. Elective cesarean section was performed at 33 weeks of gestational age due to anhydramnios. A female symmetric small for gestational age baby with dysmorphic features and an Apgar score of 9/10/10 was born. She had a good clinical outcome during hospitalization. Postnatal peripheral blood karyotype was normal. Interphase fluorescence in situ hybridization in a sample of the oral mucosa confirmed the prenatal diagnosis. At three months of corrected age she had a normal psychomotor development.ConclusionTo the best of our knowledge, this is the first reported case of mosaic partial tetrasomy 18 including segments of the long arm. This newborn's relatively mild phenotype highlights the challenges of prenatal genetic counselling in mosaic cases with fetal anomalies.     

Prenatal diagnosis of a de novo 9p terminal chromosomal deletion in a fetus with major congenital anomalies

ObjectiveWe describe a prenatal ultrasonography diagnosis of omphalocele and symbrachydactyly in a fetus and review the literature on prenatal diagnosis of 9p terminal chromosomal deletions.Case reportA 31-year-old woman (gravida 3, para 1) was referred for genetic counseling because a fetal omphalocele had been detected. Prenatal ultrasonography at 17+ weeks of gestational age revealed a singleton female fetus with biometry equivalent to 18 weeks with an omphalocele. In addition, symbrachydactyly was also noted in the right arm; the wrist bones as well as the metacarpals were missing. A chromosomal study was arranged for a congenital anomaly involving omphalocele. We obtained Giemsa-banded chromosomes from fetal tissue cells, and an abnormal male karyotype with a terminal deletion of the short arm of chromosome 9 at band 9p13 was noted. After delivery, the fetus showed omphalocele, symbrachydactyly, trigonocephaly, sex reversal, a long philtrum, low-set ears, telecanthus, and a frontal prominence.ConclusionPrenatal diagnosis of abnormal ultrasound findings with omphalocele and symbrachydactyly should include the differential diagnosis of a chromosome 9p deletion.     

Chromosomal microarray analysis in fetuses with high-risk prenatal indications: A retrospective study in China

ObjectiveThe present study aimed to determine the diagnostic value of prenatal chromosomal microarray analysis (CMA) for fetuses with several indications of being at high risk for various conditions.Materials and methodsThis retrospective analysis included 1256 pregnancies that were prenatally evaluated due to high-risk indications using invasive CMA. The indications for invasive prenatal diagnosis mainly included ultrasound anomalies, high-risk for maternal serum screening (MSS), high-risk for non-invasive prenatal tests (NIPT), family history of genetic disorders or birth defects, and advanced maternal age (AMA). The rate of clinically significant genomic imbalances between the different groups was compared.ResultsThe overall prenatal diagnostic yield was 98 (7.8%) of 1256 pregnancies. Clinically significant genomic aberrations were identified in 2 (1.5%) of 132 patients with non-structural ultrasound anomalies, 36 (12.7%) of 283 with structural ultrasound anomalies, 2 (4.5%) of 44 at high-risk for MSS, 38 (26.6%) of 143 at high-risk for NIPT, 11 (3.8%) of 288 with a family history, and 7 (2.1%) of 328 with AMA. Submicroscopic findings were identified in 29 fetuses, 19 of whom showed structural ultrasound anomalies.ConclusionThe diagnostic yields of CMA for pregnancies with different indications greatly varied. CMA could serve as a first-tier test for structural anomalies, especially multiple anomalies, craniofacial dysplasia, urinary defects, and cardiac dysplasia. Our results have important implications for genetic counseling.     

染色体核型分析联合染色体微阵列分析在平衡易位/倒位携带者产前诊断中的应用价值

目的:探讨染色体核型分析与染色体微阵列分析（chromosomal microarray analysis,CMA）技术在染色体平衡易位/倒位携带者产前诊断中的应用价值。方法:本研究为回顾性研究。纳入既往因自然流产（≥2次）、死胎、胎儿多发畸形或染色体异常患儿生育史,夫妇双方行外周血染色体核型分析和荧光原位杂交检测确诊...     

6例9p24区微缺失胎儿的产前诊断与遗传学分析

目的:对6例9p24区微缺失的胎儿进行产前诊断与遗传学分析。方法:回顾性分析2018年1月至2020年1月因血清学唐氏综合征筛查高风险/临界高风险就诊于河南省人民医院遗传咨询门诊6例孕妇的遗传学检测资料。采用常规G显带和微阵列比较基因组杂交（array comparative genomic hybridization...     

圆锥动脉干畸形胎儿297例的产前诊断和临床结局分析

目的:分析圆锥动脉干畸形（CTD）胎儿的产前诊断结果及临床结局,探讨CTD与染色体异常的相关性。方法:收集2011年1月1日至2019年12月31日在广州市妇女儿童医疗中心产前诊断中心因CTD进行介入性产前诊断及染色体分析的胎儿297例。根据超声诊断将CTD胎儿分为法洛四联症（109例）、肺动脉（干）闭锁（30例）、大...     

Prenatal diagnosis of tetrasomy 9p in a 19-week-old fetus with Dandy-Walker malformation: a case report

OBJECTIVE: The presentation of sonographic and perinatal findings of tetrasomy 9p. METHODS AND RESULTS: Chorionic villus sampling and amniocentesis were performed at 19 weeks of gestation because of the sonographic findings of Dandy-Walker malformation with bilateral ventriculomegaly. Cytogenetic analysis showed 47,XX,+i psu dic(9)(pter->q12::q12>-pter). The pregnancy was terminated at 20 weeks of gestation at the request of the parents. At post-mortem examination, the presumed hypoplasia of the vermis could not be confirmed for technical reasons. No other pathological findings were seen. CONCLUSION: From our experience and from the literature, we conclude that Dandy-Walker malformation is an important finding in tetrasomy 9p. Chromosomal studies should be carried out in fetuses with sonographically detected Dandy-Walker malformation, even in the absence of other abnormalities.     

单纯性染色体18p部分三体综合征患儿的产前遗传学诊断和文献回顾

目的探讨单纯性染色体18P部分三体综合征患者的产前诊断特点。方法联合运用传统染色体核型分析和染色体微阵列(chromosome microarray analysis,CMA)基因芯片技术对家系成员行染色体核型分析和基因组拷贝数变异检测。结果胎儿羊水染色体核型结果为46,XY,der(18),父母双方染色体核型均未见异常;胎儿基因芯片检测结果为arr[hg19]18p11.31p11.21(3,521,718-15,099,116)×3,即胎儿基因组18号染色体短臂p11.31p11.21区域存在11.58 Mb的片段重复,父母双方基因芯片结果均为阴性,提示该胎儿的18号染色体结构重排为新发生的。结论在一个有不良生育史家系的胎儿中检出一个罕见新发的单纯性染色体18p部分三体变异,这是世界少见的单纯性染色体18p部分三体综合征的产前病例报道。联合运用传统染色体核型分析和C M A基因芯片技术在预防不良产史家系中胎儿出生缺陷的产前诊断中具有重要的临床应用价值。     

Prenatal diagnosis of scrotal-inguinal hernia: two case reports and review of the English literature

We present two cases of a prenatal diagnosis of inguinal hernia and the fetal outcome. Initial differential diagnosis included sacrococcygeal teratoma and testicular termatoma, while the final diagnosis was scrotal-inguinal hernia based on sonographic visualization of bowel loop movement in the scrotal mass.     

Prenatal diagnosis of a familial 5p14.3-p14.1 deletion encompassing CDH18, CDH12, PMCHL1, PRDM9 and CDH10 in a fetus with congenital heart disease on prenatal ultrasound

Objective

We present prenatal diagnosis of a familial 5p14.3-p14.1 deletion in a fetus with congenital heart disease on prenatal ultrasound.

Prenatal diagnosis of tetrasomy 47,XY,+i(12p) confirmed by in situ hybridization

A case of tetrasomy i(12p) detected prenatally is reported. The patient, a black, 32-year-old G3P2002 at 24 weeks' gestation with an unremarkable family history presented herself for prenatal care. Ultrasound examination showed a fetus with diminished femoral and humeral lengths, and hydramnios. A level II scan confirmed the presence of an omphalocele. Amniocentesis at 31 weeks showed 47,XY,+i(12p) karyotype. An infant with multiple congenital anomalies was delivered at 34 weeks. The infant died after 5 h. Genetic and ultrasonographic examinations in the third trimester were helpful in the investigation of this fetus with multiple congenital anomalies. The careful, complete team counselling afforded by this approach enabled the mother and family to be well adjusted to the strong possibility (and subsequent reality) of an abnormal infant.     

Prenatal diagnosis and molecular cytogenetic characterization of de novo distal 5p deletion and distal 22q duplication

ObjectiveWe present prenatal diagnosis and molecular cytogenetic characterization of de novo distal 5p deletion and distal 22q duplication.Case reportA 34-year-old woman was underwent amniocentesis at 17 weeks of gestation because of advanced maternal age. Amniocentesis revealed a derivative chromosome 5 [der(5)] with an abnormal distal 5p segment of unknown origin. The parental karyotypes were normal. Array comparative genomic hybridization (aCGH) analysis was performed on the cultured amniocytes, and the result was arr 5p15.33p13.3 (22,149–29,760,922) × 1.0, arr 22q13.2q13.33 (42, 192, 065–51,178,264) × 3.0 [GRCh37 (hg19)] with a 29.739-Mb deletion of 5p15.33-p13.3 encompassing 55 [Online Mendelian Inheritance in Man (OMIM)] genes including TPPP, TERT, SRD5A1, SEMA5A and CTNND2, and an 8.986-Mb duplication of 22q13.2-q13.33 encompassing 82 OMIM genes including TRMU, SCO2, TYMP, CPT1B and SHANK3. The fetal karyotype was 46,XY,der(5)t(5; 22)(p13.3; q13.2)dn. The pregnancy was subsequently terminated, and a malformed fetus was delivered with facial dysmorphism. Postnatal polymorphic DNA marker analysis confirmed a maternal origin of the aberrant chromosome 5.ConclusionaCGH and polymorphic DNA marker analyses can determine the nature and parental origin of the de novo chromosome aberration, and the information acquired is useful for genetic counseling.