Prenatal diagnosis of partial monosomy 2q (2q37.3→qter) and partial trisomy 10q (10q24.31→qter) of paternal origin associated with increased nuchal translucency and abnormal maternal serum screening results

ObjectiveWe present prenatal diagnosis of terminal 2q deletion and distal 10q duplication of paternal origin in a fetus associated with increased nuchal translucency and abnormal maternal serum screening results.Case reportA 26-year-old woman who had experienced spontaneous abortion twice underwent amniocentesis at 16 weeks of gestation because of an increased nuchal translucency thickness of 3.5 mm at 12 weeks of gestation and abnormal maternal serum screening results of 2.573 multiples of the median (MoM) of free β-human chorionic gonadotrophin (β-hCG) and 1.536 MoM of pregnancy-associated plasma protein-A (PAPP-A) resulting in a trisomy 21 risk of 1:64. Amniocentesis revealed a derivative chromosome 2. Simultaneous array comparative genomic hybridization (aCGH) analysis on the DNA extracted from uncultured amniocytes revealed arr [hg19] 2q37.3 (238,294,223–242,782,258) × 1, 10q24.31q26.3 (102,018,246–135,426,386) × 3. Cytogenetic analysis of parental bloods revealed a karyotype of 46,XX in the mother and a karyotype of 46,XY,t(2;10)(q37.3;q24.3) in the father. The fetal karyotype was 46,XX,der(2)t(2;10)(q37.3;q24.3)pat. The pregnancy was terminated at 20 weeks of gestation, and a malformed fetus was delivered with facial dysmorphism. Postnatal analysis of the cord blood confirmed the results of prenatal diagnosis. The fetus had a 4.693-Mb deletion of 2q37.3 encompassing the genes of HDAC4, KIF1A, PASK, HDLBP, FARP2 and D2HGDH, and a 33.34-Mb duplication of 10q24.31-q26.3 encompassing the gene of NFκB2.ConclusionFirst-trimester ultrasound and maternal serum biochemistry screening may help to identify an unexpected unbalanced familial translocation at prenatal diagnosis.     

Mosaic deletion-duplication syndrome of chromosome 3: prenatal molecular cytogenetic diagnosis using cultured and uncultured amniocytes and association with fetoplacental discrepancy

ObjectiveTo present prenatal molecular cytogenetic diagnosis of mosaicism for terminal 3p deletion and distal 3q duplication using cultured and uncultured amniocytes, and the association with fetoplacental discrepancy.Materials, Methods, and ResultsA 35-year-old primigravid woman was referred for genetic counseling at 21 weeks of gestation because of 20% (5/25 colonies) mosaicism for add(3)(p26) detected by amniocentesis. Repeated amniocenteses were performed. Array comparative genomic hybridization (aCGH) and interphase fluorescence in situ hybridization (FISH) were applied in the uncultured amniocytes. aCGH analysis detected 0.15-Mb microdeletion of 3p26.3 with CHL1 haploinsufficiency and a 49.42-Mb duplication of 3q24-q29 in the uncultured amniocytes. Interphase FISH analysis revealed 27.3% mosaicism (12/44 cells) in the uncultured amniocytes. Metaphase FISH analysis revealed 23.3% mosaicism (7/30 cells) in the cultured amniocytes. Conventional cytogenetic analysis showed a karyotype of 46,XX,der(3)(qter → q24::p26.3 → qter)[10]/46,XX[20] (33% mosaicism). Subsequent fetal blood sampling showed a karyotype of 46,XX,der(3) (qter → q24::p26.3 → qter)[5]/46,XX[35] (12.5% mosaicism). The parents elected to terminate the pregnancy, and a malformed fetus was delivered at 24 weeks of gestation with characteristic facial dysmorphism and clinodactyly of the hands. Cytogenetic analysis of the extraembryonic tissues revealed the results of 46,XX (40 cells) in placenta, 25% mosaicism (10/40 cells) in amniotic membrane and 50% mosaicism (20/40 cells) in umbilical cord.ConclusionOur presentation highlights the utility of molecular cytogenetic technologies in prenatal diagnosis of rare mosaic chromosome rearrangements and provides evidence for fetoplacental discrepancy under such circumstances.     

Molecular cytogenetic characterization of a duplication of 15q24.2-q26.2 associated with anencephaly and neural tube defect

Objective

We present molecular cytogenetic characterization of a duplication of 15q24.2-q26.2 associated with anencephaly and neural tube defect (NTD).

Prenatal diagnosis of concomitant distal 5q duplication and terminal 10q deletion in a fetus with intrauterine growth restriction,congenital diaphragmatic hernia and congenital heart defects

ObjectiveWe present prenatal diagnosis of concomitant distal 5q duplication and terminal 10q deletion in a fetus with intrauterine growth restriction (IUGR), congenital diaphragmatic hernia (CDH) and congenital heart defects (CHD).Case reportA 34-year-old, gravida 4, para 2, woman was referred for amniocentesis at 21 weeks of gestation because of advanced maternal age and IUGR. There was no congenital malformation in the family. Amniocentesis revealed a derivative chromosome 10 with an additional maternal on the terminal region of 10q. Array comparative genomic hybridization (aCGH) analysis on the DNA extracted from the cultured amniocytes revealed a result of arr 5q31.3q35.5 (142, 548, 354–180,696,806) × 3.0, arr 10q26.3 (132, 932, 808–135,434,178) × 1.0 [GRCh37 (hg19)] with a 2.50-Mb deletion of 10q26.3 encompassing 19 [Online Mendelian Inheritance in Man (OMIM)] genes and a 38.15-Mb duplication of 5q31.3-q35.5 encompassing 195 OMIM genes including four CDH candidate genes of NDST1, ADAM19, NSD1 and MAML1. The mother was found to have a karyotype of 46,XX,t(5; 10) (q31.3; q26.3). Therefore, the fetal karyotype was 46,XX,der(10)t(5; 10)(q31.3; q26.3)mat. Prenatal ultrasound showed IUGR, right CDH, transposition of great artery, double outlet of right ventricle and right atrial isomerism. The pregnancy was terminated, and a malformed fetus was delivered with facial dysmorphism.ConclusionFetuses with concomitant distal 5q duplication and terminal 10q deletion may present IUGR, CDH and CHD on prenatal ultrasound.     

Prenatal diagnosis of low-level mosaicism for a small supernumerary marker chromosome derived from chromosome 9q (9q13-q21.33) in a pregnancy with a favorable outcome,and cytogenetic discrepancy between cultured amniocytes and uncultured amniocytes

ObjectiveWe present prenatal diagnosis of low-level mosaicism for a small supernumerary marker chromosome (sSMC) derived from chromosome 9q (9q13-q21.33) in a pregnancy with a favorable outcome, and cytogenetic discrepancy between cultured amniocytes and uncultured amniocytes.Case reportA 36-year-old, primigravid woman underwent amniocentesis at 17 weeks of gestation because of advanced maternal age. Cytogenetic analysis on cultured amniocytes revealed a karyotype of 46,XY in 20/20 colonies. Simultaneous array comparative genomic hybridization (aCGH) on the DNA extracted from uncultured amniocytes revealed 30% mosaicism for a de novo 20.3-Mb gene dosage increase at 9q13-q21.33. Repeat amniocentesis and cordocentesis were performed at 21 weeks of gestation. Cytogenetic analysis on cord blood revealed a karyotype of 47,XY,+mar [3]/46,XY [37]. aCGH analysis of cord blood revealed 7.5% mosaicism for a 17.15-Mb gene dosage increase at 9q21.11-q21.33. aCGH analysis of uncultured amniocytes revealed 11.7% mosaicism for a 17.15-Mb gene dosage increase at 9q21.11-q21.33. Polymorphic DNA marker analysis excluded uniparental disomy 9. The parental karyotypes were normal. The pregnancy was carried to 37 weeks of gestation, and a 2955-g phenotypically normal male baby was delivered. At birth, the cord blood had a karyotype of 47,XY,+mar [3]/46,XY [37], the placenta had a karyotype of 47,XY,+mar [10]/46,XY [30], and the umbilical cord had a karyotype of 47,XY,+mar [14]/46,XY [36]. aCGH analysis on the DNA extracted from cord blood at birth revealed no genomic imbalance. Interphase fluorescence in situ hybridization analysis on buccal mucosal cells at age two months detected 3.8% (4/106 cells) mosaicism for the sSMC, compared with 2% (2/100 cells) in the normal control. The neonate had normal physical development at age two months.ConclusionCytogenetic discrepancy between cultured amniocytes and uncultured amniocytes may exist in the pregnancy with fetal mosaic sSMC. Low-level mosaicism for an sSMC derived from chromosome 9q13-q21.33 at prenatal diagnosis can be associated with a favorable outcome in the fetus.     

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.     

Molecular cytogenetic characterization of 1q42.3q44 deletion and 8q24.3 duplication in a fetus with single umbilical artery and ventricular septal defects

ObjectiveWe present prenatal diagnosis and molecular cytogenetic characterization of a chromosome 1q42.3q44 deletion and 8q24.3 duplication in a fetus with single umbilical artery and ventricular septal defects, and we discuss the genotype–phenotype correlation.Case reportHere, we describe a fetus with abnormal sonography findings showing a single umbilical artery and ventricular septal defects. Conventional karyotyping initially described the fetus as 46,XX,1q? and molecular cytogenetic analysis (CMA) revealed a 13-Mb deletion and 4.6-Mb duplication of regions 1q42.3q44 and 8q24.3, respectively. The father's karyotype was 46,XY. The mother's karyotype was 46,XX,t(1;8)(q42;q24). Therefore, the karyotype of the fetus was identified as 46,XX,der(1)t(1;8)(q42;q24) mat. After genetic counseling, the couple chose to terminate the pregnancy. We suggest that the ACTN2, RYR2 and PUF60 genes may be responsible for the ultrasound abnormalities observed in the fetus.ConclusionTo the best of our knowledge, this is the first report of a 1q deletion and 8q duplication identified by prenatal detection. The application of karyotype analysis and CMA provides more accurate characterization for unidentified chromosomal anomalies, and benefits appropriate genetic counseling in the clinic.     

Chromosome 15q overgrowth syndrome: prenatal diagnosis, molecular cytogenetic characterization, and perinatal findings in a fetus with dup(15)(q26.2q26.3)

ObjectiveTo present molecular cytogenetic characterization of a prenatally detected duplication of 15q26.2 → q26.3 in a fetus with overgrowth.Case ReportA 34-year-old para 0 woman underwent amniocentesis at 18 weeks of gestation because of advanced maternal age. Amniocentesis revealed a derivative chromosome 15, or der(15), with additional material at the end of the long arm of one chromosome 15. Parental karyotypes were normal. Fetal overgrowth was first noted at 21 weeks of gestation. Repeated amniocentesis was performed at 22 weeks of gestation. Array comparative genomic hybridization revealed a 4.71-Mb duplication from 15q26.2 to 15q26.3 encompassing the IGF1R gene. Fluorescence in situ hybridization analysis using the bacterial artificial chromosome clone probes specific for 15q26.2-q26.3 and the subtelomeric region of 15q showed a direct duplication and no terminal deletion in the der(15). Polymorphic DNA marker analysis determined a paternal origin of the duplication of 15q. Level II ultrasound at 23 weeks of gestation revealed a fetal biometry equivalent to 26 weeks. The pregnancy was subsequently terminated, and a 1062-g (>99^th centile) malformed fetus was delivered at 24 weeks of gestation with craniofacial dysmorphism, craniosynostosis, and overgrowth.ConclusionThe present case provides evidence for prenatal overgrowth, craniosynostosis, and characteristic facial dysmorphism in association with a duplication of 15q26.2 → q26.3 and a duplication of the IGF1R gene. Prenatal diagnosis of fetal overgrowth should include a differential diagnosis of the chromosome 15q overgrowth syndrome.     

Detection of de novo del(18)(q22.2) and a familial of 15q13.2-q13.3 microduplication in a fetus with congenital heart defects

ObjectiveWe present detection of de novo del(18)(q22.2) and a familial 15q13.2-q13.3 microduplication in a fetus with congenital heart defects (CHD).Case reportA 27-year-old, primigravid woman was referred for genetic counseling because of fetal CHD. Prenatal ultrasound at 17 weeks of gestation revealed pericardial effusion, cardiomegaly and a large ventricular septal defect. The pregnancy was subsequently terminated at 18 weeks of gestation, and a 192-g female fetus was delivered with facial dysmorphism. Cytogenetic analysis of the umbilical cord revealed a karyotype of 46,XX,del(18)(q22.2). The parental karyotypes were normal. Array comparative genomic hybridization (aCGH) of the placental tissue revealed a 2.08-Mb 15q13.2-q13.3 microduplication encompassing KLF13 and CHRNA7, and a 10.74-Mb 18q22.2-q23 deletion encompassing NFATC1. The phenotypically normal father carried the same 2.08-Mb 15q13.2-q13.3 microduplication. Polymorphic DNA marker analysis confirmed a paternal origin of the distal 18q deletion.ConclusionPrenatal diagnosis of CHD should include a complete genetic study of the embryonic tissues, and the acquired information is useful for genetic counseling.     

Prenatal diagnosis and molecular cytogenetic characterization of a chromosome 1q42.3-q44 deletion in a fetus associated with ventriculomegaly on prenatal ultrasound

ObjectiveWe present prenatal diagnosis and molecular cytogenetic characterization of a chromosome 1q42.3-q44 deletion in a fetus associated with ventriculomegaly on prenatal ultrasound, and we discuss the genotype–phenotype correlation.Case reportA 36-year-old woman underwent amniocentesis at 17 weeks of gestation because of advanced maternal age. Amniocentesis revealed a karyotype of 46,XX,del(1) (q42.3q44). Simultaneous array comparative genomic hybridization analysis on uncultured amniocytes revealed arr 1q42.3q44 (234,747,397–246,081,267) × 1 [GRCh37 (hg19)] with an 11.33-Mb 1q42.3-q44 deletion encompassing RGS7, FH, CEP170, AKT3, ZBTB18 and HNRNPU. The parental karyotypes were normal. Prenatal ultrasound at 20 weeks of gestation revealed bilateral ventriculomegaly and dilation of the third ventricle. The pregnancy was subsequently terminated, and a malformed female fetus was delivered with characteristic facial dysmorphism. Postnatal conventional and molecular cytogenetic analyses confirmed the prenatal diagnosis. Polymorphic DNA marker analysis showed a paternal origin of the distal 1q deletion in the fetus.ConclusionFetuses with a chromosome 1q42.3-q44 deletion may present ventriculomegaly on prenatal ultrasound. Prenatal diagnosis of ventriculomegaly should include a differential diagnosis of chromosome 1q distal deletions, and aCGH is useful under such a circumstance.     

Molecular genetic characterization of a prenatally detected 1.484-Mb Xq13.3-q21.1 duplication encompassing ATRX and a literature review of syndromic intellectual disability and congenital abnormalities in males with a duplication at Xq13.3-q21.1

Objective

We present prenatal diagnosis of dup(X)(q13.3q21.1) in a male fetus and molecular genetic analysis in three generations and a literature review of syndromic intellectual disability and congenital abnormalities in males with a duplication at Xq13.3-q21.1.

Molecular cytogenetic characterization of Jacobsen syndrome (11q23.3-q25 deletion) in a fetus associated with double outlet right ventricle,hypoplastic left heart syndrome and ductus venosus agenesis on prenatal ultrasound

Objective

We present molecular cytogenetic characterization of Jacobsen syndrome (11q23.3-q25 deletion) in a fetus associated with double outlet right ventricle (DORV), hypoplastic left heart syndrome (HLHS), and ductus venosus (DV) agenesis on prenatal ultrasound.

Molecular cytogenetic characterization of 2q deletion and Xq duplication associated with nasal bone dysplasia in prenatal diagnosis: A case report and literature review

ObjectiveWe report a prenatal case of male fetus with a 2q13 deletion and an Xq27.3q28 duplication, presenting nasal bone dysplasia by ultrasound examination. And we compare the similarities of clinical features of cases consisting of similar 2q deletion and Xq duplication.Case reportA 30-year-old woman was referred for prenatal diagnosis and genetic counseling at 24 weeks of gestation. Prenatal ultrasound showed nasal bone dysplasia of the fetus. Amniocentesis revealed the karyotype of the fetus as 46, XY and the results of chromosomal microarray analysis was arr[GRCh37] 2q13(110467258–111370025)x1, arr[GRCh37]Xq27.3q28(144050780–149748782)x2. The parents both have normal karyotypes. The couple chose to continue the pregnancy and finally delivered a male infant at 39 weeks of gestation. His weight was 2850 g and length was 50 cm. Physical examination of the newborn revealed no apparent anomalies. Until the boy was one year old, there was no abnormalities in his growth and development. The long-term follow-up till adulthood for the healthy infant is necessary.ConclusionThe development of CMA plays a critical role in prenatal diagnosis and genetic counseling for unidentified chromosomal anomalies. More clinical information and further studies of patients with these anomalies will identify the pathogenicity of the involving genes and improve the understanding of the phenotype–genotype correlation.     

Prenatal diagnosis of de novo int22h1/int22h2-mediated Xq28 duplication syndrome involving RAB39B following a previous ambiguous genitalia pregnancy

ObjectiveTo report a prenatal diagnosis of int22h1/int22h2-mediated Xq28 duplication syndrome.Case reportHerein, we present the case of a 28-year-old female who had a previous ambiguous genitalia pregnancy without genetic abnormality that was terminated at 23⁺² weeks of gestation. The fetus of the current pregnancy harbored a de novo copy number variation at the Xq recurrent region (int22h1/int22h2-flanked; including the RAB39B gene) with a 0.397 Mb microduplication. The literature suggests the clinical manifestation of int22h1/int22h2-mediated Xq28 duplication syndrome tends to show a milder clinical phenotype in females than males. Although the fetus in this case was female, taking into consideration the parents' age and culture, the family decided to terminate this pregnancy due to the genetic abnormality.ConclusionPrenatally diagnosed de novo int22h-1/int22h-2-mediated Xq28 duplication syndrome exhibits variable phenotypic traits in female fetuses.     

Prenatal diagnosis and molecular cytogenetic characterization of a de novo duplication of 2q12.2→q13 encompassing MALL,NPHP1, RGPD6 and BUB1

ObjectiveWe present prenatal diagnosis and molecular cytogenetic characterization of a de novo duplication of 2q12.2→q13 encompassing MALL, NPHP1, RGPD6 and BUB1.Case reportA 36-year-old, primigravid woman underwent amniocentesis at 16 weeks of gestation because of advanced maternal age. Amniocentesis revealed a karyotype of 46,XX,dup(2) (q12.2q13). Simultaneous array comparative genomic hybridization (aCGH) analysis revealed a 6.1-Mb 2q12.2q13 duplication. aCGH analysis of the parental bloods did not find such a duplication. Prenatal ultrasound was unremarkable. After genetic counseling, the parents decided to terminate the pregnancy at 21 weeks of gestation, and a 420-g female fetus was delivered with no gross abnormalities. Postnatal cytogenetic analysis of the umbilical cord confirmed the prenatal diagnosis. The parental karyotypes were normal. aCGH analysis of the umbilical cord revealed the result of arr [GRCh37 (hg19)] 2q12.2q13 (107, 132, 950–113,065,779) × 3.0 with a 2q12.2→q13 duplication encompassing 20 OMIM genes including MALL, NPHP1, RGPD6 and BUB1. Polymorphic DNA marker analysis of quantitative fluorescence polymerase chain reaction (QF-PCR) on the DNAs extracted from the umbilical cord and parental bloods confirmed a maternal origin of the duplication of 2q12.2→q13.ConclusionAmniocentesis may incidentally detect a de novo chromosomal segmental duplication of maternal origin in the fetus. The genetic information acquired by molecular analyses such as aCGH and QF-PCR are useful for genetic counseling under such a circumstance.     

Prenatal diagnosis and molecular cytogenetic characterization of a de novo interstitial duplication of 14q (14q31.3→q32.12) associated with abnormal maternal serum biochemistry

ObjectiveTo present prenatal diagnosis and molecular cytogenetic characterization of a de novo interstitial duplication of 14q (14q31.3→q32.12) in a pregnancy associated with abnormal maternal serum biochemistry.Case ReportA 19-year-old woman underwent amniocentesis in the second trimester because of abnormal maternal serum biochemistry. Her husband was 33 years old. At 16 weeks of gestation, the levels of α-fetoprotein, unconjugated estriol, total β-human chorionic gonadotropin, and inhibin A were 0.8 multiples of median (MoM), 0.84 MoM, 3.06 MoM, and 1.14 MoM, respectively, consistent with a positive trisomy 21 risk of 1/269. Results of an amniocentesis revealed a small de novo interstitial duplication of 14q encompassing 14q31-q32.1. An array comparative genomic hybridization analysis detected a 6.6-Mb duplication at chromosome 14q31.3-q32.12. Results of a fluorescence in situ hybridization analysis showed a direct duplication of interstitial 14q. The karyotype was 46,XY,dup(14) (q31.3q32.12). Level II ultrasound was unremarkable. The parents decided to continue the pregnancy. A 3805-g healthy male baby was delivered at 39 weeks of gestation. When examined at 6 months of age, the neonate was normal in growth and psychomotor development with no apparent phenotypic abnormalities, although long-term follow-ups are required.ConclusionAbnormal maternal serum biochemistry in the second trimester may be a distinctive prenatal feature in pregnancy associated with fetal chromosome 14q duplication.     

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 and molecular cytogenetic characterization of mosaicism for a small supernumerary marker chromosome derived from 2q11.1-q12.1 associated with fetal bilateral radial dysplasia

ObjectiveWe present prenatal diagnosis and molecular cytogenetic characterization of mosaicism for a small supernumerary marker chromosome (sSMC) derived from 2q11.1-q12.1 associated with fetal bilateral radial dysplasia.Case reportA 27-year-old woman underwent amniocentesis at 18 weeks of gestation because of club hands on fetal ultrasound. The internal organs of the fetus were normal. Amniocentesis revealed a karyotype of 47,XY,+mar [13]/46,XY [11]. The parental karyotypes were normal. Simultaneous array comparative genomic hybridization (aCGH) analysis of the DNA extracted from uncultured amniocytes revealed the result of arr 2q11.1q12.1 (95,529,039–102,825,556) × 3.0 [GRCh37 (hg19)]. The pregnancy was terminated at 20 weeks of gestation, and a malformed fetus was delivered with isolated bilateral radial dysplasia. The cord blood had a karyotype of 47,XY,+mar[24]/46,XY[16]. Polymorphic DNA marker analysis of the DNAs extracted from umbilical cord and parental bloods excluded uniparental disomy for chromosome 2. Metaphase fluorescence in situ hybridization analysis confirmed an sSMC derived from chromosome 2q11.1-q12.1 in cultured amniocytes.ConclusionHigh-level mosaicism for an sSMC derived from chromosome 2q11.1-q12.1 can be associated with fetal abnormalities.     

7号染色体末端三体和13号染色体末端单体致胎儿多发畸形的产前诊断

目的:产前诊断1例胎儿宫内发育迟缓、先天发育异常,脑积水,丹迪沃克综合征,脊柱裂,先天性心脏病,足内翻等的原因,为再次妊娠提供信息。方法:用常规G显带技术分析胎儿羊水染色体及其父母外周血染色体,并用多重连接探针扩增技术(MLPA)和微列阵比较基因组杂交芯片(array-CGH)进行精确分析。结果:胎儿13号染色体出现异常,具体异常情况不明确。MLPA检测显示,胎儿13q32-34出现缺失;array-CGH进一步分析显示,胎儿7号染色体部分三体,重复区域为q31.33-q36.3,片段大小34.74Mb,13号染色体部分单体,缺失区域为q31.3-q34,片段大小为25.88Mb;胎儿的异常染色体来源于父亲。结论:7q部分三体和13q部分单体是胎儿异常表型的主要原因,MLPA技术在产前胎儿检测中起着高效价廉的筛选作用,array-CGH为明确微小重复和缺失提供了技术手段。     

Prenatal diagnosis and molecular cytogenetic characterization of a derivative chromosome der(18;18)(q10;q10)del(18)(q11.1q12.1)del(18)(q22.1q22.3) presenting as apparent isochromosome 18q in a fetus with holoprosencephaly

ObjectiveTo present prenatal diagnosis and molecular cytogenetic characterization of a derivative chromosome der(18;18)(q10;q10)del(18)(q11.1q12.1)del(18)(q22.1q22.3).Materials, Methods, and ResultsA 32-year-old woman was referred for genetic counseling of prenatally detected isochromosome 18q [i(18q)]. She had undergone amniocentesis at 19 gestational weeks because of a trisomy 18 risk of 1/39 derived from abnormally low levels of maternal serum unconjugated estriol, inhibin A, α-fetoprotein, and total β-human chorionic gonadotropin. Amniocentesis revealed a karyotype of 46,XX,i(18)(q10). Parental karyotypes were normal. Prenatal ultrasound showed alobar holoprosencephaly. Repeated amniocentesis was requested and performed at 21 gestational weeks. Array-comparative genomic hybridization analyses revealed a 14-Mb deletion of 18p11.32-p11.21, a 37.8-Mb duplication of 18q12.1-q22.1, and a 6.9-Mb duplication of 18q22.3-q23. Metaphase fluorescence in situ hybridization study showed the absence of an 18q12.1-specific probe signal in one arm and the absence of an 18q22.2-specific probe signal in the other arm of the derivative chromosome. Quantitative fluorescent polymerase chain reaction analysis determined a paternal origin of the derivative chromosome. The cytogenetic result was 46,XX,der(18;18)(q10;q10)del(18)(q11.1q12.1)del(18)(q22.1q22.3). The fetus postnatally manifested cebocephaly.ConclusionConcomitant monosomy 18p and trisomy 18q can be associated with holoprosencephaly and abnormal maternal serum screening results. Array-comparative genomic hybridization, fluorescence in situ hybridization, and quantitative fluorescent polymerase chain reaction are useful in genetic counseling of prenatally detected isochromosomes by providing information on the origin and genetic components of the isochromosome.