Rapid diagnosis of trisomy 18 of maternal origin by quantitative fluorescent polymerase chain reaction analysis following tissue culture failure for conventional cytogenetic analysis in a fetus with holoprosencephaly,ventricular septal defect,arthrogryposis of bilateral wrists and aplasia of the thumbs

ObjectiveWe present rapid diagnosis of trisomy 18 of maternal origin by quantitative fluorescent polymerase chain reaction (QF-PCR) analysis following tissue culture failure for conventional cytogenetic analysis in a fetus with holoprosencephaly (HPE), ventricular septal defect (VSD), arthrogryposis of bilateral wrists and aplasia of the thumbs.Case reportA 22-year-old, primigravid woman was referred for first-trimester ultrasound screening at 13 weeks of gestation, and the fetus was found to have HPE and VSD. The pregnancy was subsequently terminated at 14 weeks of gestation, and a malformed fetus was delivered with cebocephaly, arthrogryposis of bilateral wrists and aplasia of the thumbs. The umbilical cord and placental tissues were collected for genetic analysis. However, tissue culture failure for conventional cytogenetic analysis occurred because of contamination. QF-PCR analysis using the polymorphic DNA markers of D18S1369 (18q12.2) and D18S1361 (18q22.3) confirmed trisomy 18 of maternal origin.ConclusionQF-PCR analysis is useful for rapid confirmation of trisomy 18 and the parental origin when tissue culture failure for conventional cytogenetic analysis occurs in pregnancy suspicious of fetal trisomy 18.     

Rapid confirmation of trisomy 13 of maternal origin by QF-PCR following postmortem tissue cell culture failure in a pregnancy with trisomy 13 at amniocentesis and fetal postaxial polydactyly and facial cleft

ObjectiveWe present rapid confirmation of trisomy 13 of maternal origin by quantitative fluorescent polymerase chain reaction (QF-PCR) following postmortem tissue cell culture failure in a pregnancy with trisomy 13 at amniocentesis and fetal postaxial polydactyly and facial cleft.Case ReportA 34-year-old woman underwent amniocentesis at 17 weeks of gestation because of advanced maternal age. Cytogenetic analysis of cultured amniocytes revealed a karyotype of 47,XX,+13. Prenatal ultrasound revealed postaxial polydactyly. The pregnancy was subsequently terminated, and a malformed fetus was delivered with facial cleft and postaxial polydactyly of the hand and foot. Postmortem cytogenetic analysis of the fetal tissue revealed no growth of the cells due to culture failure, but QF-PCR analysis on the DNA extracted from placenta, umbilical cord and parental bloods confirmed trisomy 13 and maternal origin of the extra chromosome 13.ConclusionQF-PCR analysis is useful for rapid perinatal confirmation of trisomy 13 and the parental origin of the extra chromosome 13, especially under the circumstance of tissue cell culture failure, and the acquired information is useful for genetic counseling.     

Rapid diagnosis of trisomy 13 of maternal origin by quantitative fluorescent polymerase chain reaction analysis in a pregnancy with fetal holoprosencephaly,premaxillary agenesis,postaxial polydactyly of left hand and overriding aorta

ObjectiveWe present rapid diagnosis of trisomy 13 of maternal origin by quantitative fluorescent polymerase chain reaction (QF-PCR) in a pregnancy with multiple fetal abnormalities.Case reportA 35-year-old, primigravid woman was referred for amniocentesis at 24 weeks of gestation because of multiple congenital anomalies in the fetus. Prenatal ultrasound at 23 weeks of gestation revealed holoprosencephaly, premaxillary agenesis, postaxial polydactyly of the left hand and overriding aorta. Amniocentesis was performed subsequently, and QF-PCR analysis using the polymorphic DNA markers of D13S789 (13q22.3), D13S790 (13q31.1) and D13S767 (13q31.3) on the DNA extracted from uncultured amniocytes and parental bloods showed trisomy 13 of maternal origin. Conventional cytogenetic analysis on the cultured amniocytes confirmed trisomy 13. The pregnancy was subsequently terminated, and a malformed fetus was delivered with multiple anomalies consistent with the prenatal diagnosis.ConclusionQF-PCR analysis is useful for rapid confirmation of trisomy 13 and the parental origin when prenatal ultrasound findings are suspicious of fetal trisomy 13.     

Detection of paternal origin of fetal trisomy 21 in a pregnancy with isolated ventriculomegaly but without advanced parental age

ObjectiveWe present detection of paternal origin of fetal trisomy 21 in a pregnancy with isolated ventriculomegaly but without advanced parental age.Case reportA 29-year-old pregnant woman was admitted to the hospital at 18 weeks of gestation for tocolytic treatment because of irregular uterine contractions. Her husband was 30 years old. The couple had a healthy daughter. Prenatal ultrasound incidentally found isolated ventriculomegaly, and subsequent amniocentesis revealed a karyotype of 47,XX,+21 in 20/20 colonies of cultured amniocytes. The pregnancy was terminated, and the fetus manifested characteristic craniofacial appearance of Down syndrome and hyposplastic middle phalanx of the fifth finger. Postnatal polymorphic DNA marker analysis on the DNAs extracted from the cord blood and parental bloods using quantitative fluorescent polymerase chain reaction (QF-PCR) showed a paternal origin of fetal trisomy 21. The father had a karyotype of 46, XY in 40/40 blood lymphocytes.ConclusionQF-PCR is useful for rapid confirmation of prenatally detected fetal trisomy 21 and determination of paternal origin of fetal trisomy 21 especially in pregnancies with fetal structural abnormalities but without advanced parental age.     

Prenatal diagnosis of mosaic trisomy 2 associated with abnormal maternal serum screening,oligohydramnios, intrauterine growth restriction,ventricular septal defect,preaxial polydactyly,and facial dysmorphism

ObjectiveTo present prenatal diagnosis of mosaic trisomy 2.Materials and MethodsA 29-year-old woman underwent amniocentesis at 17 weeks of gestation because of abnormal maternal serum screening, and the cytogenetic result was 47,XY,+2[8]/46,XY[22]. She underwent repeated amniocentesis at 19 weeks of gestation. Interphase fluorescence in situ hybridization (FISH), array comparative genomic hybridization (aCGH), and quantitative fluorescent polymerase chain reaction (QF-PCR) were performed on uncultured amniocytes. Ultrasound at 22 weeks of gestation revealed severe oligohydramnios, intrauterine growth restriction, and ventricular septal defect. The pregnancy was terminated at 22 weeks of gestation. Cytogenetic analysis was performed on parental blood, cultured amniocytes, cord blood, skin, liver, lung, umbilical cord, amnion, and placenta. aCGH analysis was performed on cord blood, skin, and liver.ResultsIn the samples of uncultured amniocytes, interphase FISH detected 11.1% (13/117) mosaicism for trisomy 2, aCGH analysis showed the result of arr [hg19] 2p25.3q37.3 (0–242,936,883)×2.46, and QF-PCR excluded uniparental disomy 2. QF-PCR on placenta revealed trisomy 2 derived from maternal meiosis I non-disjunction. Cytogenetic analysis revealed the following results: cultured amniocytes: 46,XY[21 colonies]; cord blood: 46,XY[40 cells]; skin: 46,XY[40 cells]; lung: 46,XY[40 cells]; liver: 47,XY,+2[4 cells]/46,XY[36 cells]; umbilical cord: 47,XY,+2[4 cells]/46,XY[36 cells]; amniotic membrane: 47,XY,+2[20 cells]/46,XY[20 cells]; and placenta: 47,XY,+2[40 cells]. The fetus postnatally manifested facial dysmorphism and preaxial polydactyly of the hand.ConclusionInterphase FISH and aCGH analyses on uncultured amniocytes are useful for rapid confirmation of low-level mosaic trisomy 2 at amniocentesis.     

Low-level mosaic trisomy 9 at amniocentesis associated with a positive non-invasive prenatal testing for trisomy 9, maternal uniparental disomy 9, intrauterine growth restriction and a favorable fetal outcome in a pregnancy

ObjectiveWe present low-level mosaic trisomy 9 at amniocentesis associated with a positive non-invasive prenatal testing (NIPT) for trisomy 9, maternal uniparental disomy (UPD) 9, intrauterine growth restriction (IUGR) and a favorable fetal outcome in a pregnancy.Case reportA 41-year-old, gravida 3, para 0, woman underwent amniocentesis at 18 weeks of gestation because of NIPT at 10 weeks of gestation suspicious of trisomy 9 in the fetus. This pregnancy was conceived by in vitro fertilization (IVF). Amniocentesis revealed a karyotype of 47,XY,+9 [2]/46,XY[23]. Simultaneous array comparative genomic hybridization (aCGH) analysis on the DNA extracted from uncultured amniocytes revealed arr (1–22) × 2, (X,Y) × 1 and detected no genomic imbalance. Polymorphic DNA marker analysis showed maternal uniparental heterodisomy 9 in the amniocytes. Prenatal ultrasound was normal. The woman was referred for genetic counseling at 22 weeks of gestation. The soluble fms-like tyrosine kinase (sFlt)/placental growth factor (PlGF) = 13.1 (normal < 38). There was no gestational hypertension. Continuing the pregnancy was advised. No repeat amniocentesis was performed because of persistent irregular contractions. IUGR was noted. A 2156-g phenotypically normal baby was delivered at 37 weeks of gestation. The cord blood and umbilical cord had a karyotype of 46,XY (40/40 cells). The placenta had a karyotype of 47,XY,+9 (40/40 cells). The parental karyotypes were normal. Quantitative fluorescence polymerase chain reaction (QF-PCR) on the DNA extracted from parental bloods, cord blood, umbilical cord and placenta revealed maternal uniparental heterodisomy 9 in cord blood and umbilical cord, and trisomy 9 of maternal origin in placenta. When follow-up at age three months, the neonate was normal in development and phenotype. The buccal mucosal cells had 3% (3/101 cells) mosaicism for trisomy 9 by interphase fluorescent in situ hybridization (FISH) analysis.ConclusionMosaic trisomy 9 at prenatal diagnosis should alert the possibility of UPD 9 and include a UPD 9 testing. Low-level mosaic trisomy 9 at amniocentesis can be associated with UPD 9 and a favorable fetal outcome.     

Prenatal diagnosis of maternal uniparental disomy 5 by amniocentesis associated with confined placental mosaicism for trisomy 5 and fetal trisomy 21 in a pregnancy

ObjectiveWe present prenatal diagnosis of maternal uniparental disomy (UPD) 5 by amniocentesis associated with confined placental mosaicism (CPM) for trisomy 5 and fetal trisomy 21 in a pregnancy.Case reportA 45-year-old woman underwent chorionic villus sampling (CVS) at 11 weeks of gestation because of maternal advanced age and an increased nuchal translucency of 4.0 mm in the first-trimester screening. CVS revealed a karyotype of 47,XY,+21[98]/48,XY,+5,+21[25]. Array comparative genomic hybridization (aCGH) analysis on the DNA extracted from chorionic villi revealed arr (5) × 3, arr (21) × 3 compatible with double trisomy 5 and trisomy 21. The woman underwent amniocenteses at 20 weeks and 22 weeks of gestation. Amniocenteses revealed a karyotype of 47,XY,+21. The parental karyotypes were normal. Quantitative fluorescent polymerase chain reaction (QF-PCR) on the DNA extracted from uncultured amniocytes showed trisomy 21 of maternal origin and maternal UPD 5. aCGH and interphase fluorescence in situ hybridization (FISH) on uncultured amniocytes confirmed trisomy 21. Prenatal ultrasound findings were unremarkable. The parents decided to continue the pregnancy, and a 2,198-g male baby was delivered at 38 weeks of gestation with characteristic phenotype of Down syndrome of hypertelorism, epicanthic folds and hypoplastic middle phalanx of the fifth fingers. Cytogenetic analysis of cord blood, umbilical cord and placenta revealed a karyotype of 47,XY,+21. QF-PCR analysis of the DNA extracted from placenta revealed double trisomy 5 and trisomy 21 with maternal gene dosage increase in chromosome 5 and chromosome 21.ConclusionPrenatal diagnosis of CPM for trisomy 5 at CVS can be associated with UPD 5 in the fetus, and UPD 5 causes no specific phenotype.     

High-level mosaic trisomy 14 at amniocentesis in a pregnancy associated with congenital heart defects and intrauterine growth restriction on fetal ultrasound

ObjectiveWe present high-level mosaic trisomy 14 at amniocentesis in a pregnancy associated with congenital heart defects (CHD) and intrauterine growth restriction (IUGR).Case reportA 34-year-old, primigravid woman underwent amniocentesis at 17 weeks of gestation because of advanced maternal age. This pregnancy was conceived by in vitro fertilization and embryo transfer (IVF-ET). Amniocentesis revealed a karyotype of 47,XX,+14[9]/46,XX[13], consistent with 40.9% (9/22 colonies) mosaicism for trisomy 14. Simultaneous array comparative genomic hybridization (aCGH) on the DNA extracted from uncultured amniocytes revealed 61% mosaicism for trisomy 14. Prenatal ultrasound at 22 weeks of gestation showed a malformed fetus with double outlet of right ventricle (DORV), ventricular septal defect (VSD), pulmonary stenosis and severe IUGR with the growth parameters equivalent to 18 weeks of gestation. The pregnancy was terminated at 23 weeks of gestation, and a 278-g female fetus was delivered with facial dysmorphism of hypertelorism, low-set small ears and wide depressed nasal bridge. Quantitative fluorescent polymerase chain reaction (QF-PCR) analysis on the DNA extracted from parental bloods, cord blood, umbilical cord and placenta confirmed a maternal origin of the extra chromosome 14 and excluded uniparental disomy (UPD) 14. The umbilical cord had a karyotype of 47,XX,+14[7]/ 46,XX[13], and the placenta had a karyotype of 47,XX,+14[4]/46,XX[36].ConclusionsHigh-level mosaic trisomy 14 at amniocentesis can be associated with abnormal ultrasound findings of CHD and IUGR.     

Mosaic trisomy 21 at amniocentesis in a twin pregnancy associated with a favorable fetal outcome,maternal uniparental disomy 21 and postnatal decrease of the trisomy 21 cell line

ObjectiveWe present mosaic trisomy 21 at amniocentesis in a twin pregnancy associated with a favorable fetal outcome, maternal uniparental disomy (UPD) 21 and postnatal decrease of the trisomy 21 cell line.Case reportA 36-year-old woman underwent elective amniocentesis at 16 weeks of gestation because of advanced maternal age, and an abnormal non-invasive prenatal testing (NIPT) result suggesting trisomy 21. Amniocentesis revealed the karyotype of 46, XX in co-twin A and the karyotype of 47,XY,+21[12]/46,XY[21] in co-twin B in the cultured amniocytes by in situ culture method. Simultaneous array comparative genomic hybridization (aCGH) analysis on uncultured amniocytes revealed the result of arr (21) × 3 [0.40] in co-twin B, consistent with 40% mosaicism for trisomy 21. Prenatal ultrasound was unremarkable, and the parental karyotypes were normal. Following genetic counseling, the parents decided to continue the pregnancy. At 36 weeks of gestation, a 2140-g female co-twin A and a 1800-g male co-twin B were delivered without any phenotypical abnormality. The karyotypes of the umbilical cord and placenta of co-twin B were 47,XY,+21[16]/46,XY[24] and 47,XY,+21 (40/40 cells), respectively. Quantitative fluorescence polymerase chain reaction (QF-PCR) analysis on the DNA extracted from parental bloods and umbilical cord, cord blood and placenta and peripheral blood at age five months of co-twin B confirmed a maternal origin of trisomy 21 and maternal uniparental isodisomy 21. aCGH analysis on the cord blood revealed the result of arr 21q11.2q22.3 × 2.25 consistent with 20%–25% (log₂ ratio = 0.15–0.2) mosaicism for trisomy 21. When follow-up at age five months, the co-twin B was phenotypically normal. His peripheral blood had a karyotype of 47,XY,+21[3]/46,XY[37]. Interphase fluorescence in situ hybridization (FISH) on 100 buccal mucosal cells detected no trisomy 21 signals. The peripheral blood had uniparental isodisomy 21.ConclusionMosaic trisomy 21 at amniocentesis can be a transient and benign condition and should alert the possibility of UPD 21. The abnormal trisomy 21 cell line in mosaic trisomy 21 at amniocentesis may decrease and disappear after birth.     

Mosaic trisomy 16 at amniocentesis in a pregnancy associated with positive non-invasive prenatal testing for trisomy 16, placental trisomy 16, intrauterine growth restriction,intrauterine fetal death,cytogenetic discrepancy between cultured amniocytes and uncultured amniocytes,and prenatal progressive decrease of the aneuploid cell line

ObjectiveWe present mosaic trisomy 16 at amniocentesis in a pregnancy associated with positive non-invasive prenatal testing (NIPT) for trisomy 16, placental trisomy 16, intrauterine growth restriction (IUGR), intrauterine fetal death (IUFD), cytogenetic discrepancy between cultured amniocytes and uncultured amniocytes and uncultured amniocytes, and prenatal progressive decrease of the aneuploid cell line.Case reportA 26-year-old, primigravid woman underwent amniocentesis at 17 weeks of gestation because of positive NIPT for trisomy 16 at 12 weeks of gestation. Amniocentesis revealed a karyotype of 47,XX,+16 [10]/46,XX[17], and simultaneous array comparative genomic hybridization (aCGH) analysis on the DNA extracted from uncultured amniocytes revealed the result of arr (16) × 3 [0.43] consistent with 43% mosaicism for trisomy 16. She was referred for genetic counseling at 19 weeks of gestation, and a fetus with IUGR was noted to have a size equivalent to 16 weeks of gestation. At 23 weeks of gestation, the fetus manifested oligohydramnios, fetal cardiomegaly and severe IUGR (fetal size equivalent to 20 weeks of gestation). Repeat amniocentesis revealed a karyotype of 46,XX (20/20 colonies) in cultured amniocytes and mosaic trisomy 16 by aCGH in uncultured amniocytes. aCGH analysis on uncultured amniocytes revealed the result of arr 16p13.3q24.3 × 2.3, consistent with 30% (log₂ ratio = 0.2) mosaicism for trisomy 16. Quantitative fluorescence polymerase chain reaction (QF-PCR) assays on the DNA extracted from parental bloods and uncultured amniocytes excluded uniparental disomy (UPD) 16. The parental karyotypes were normal. IUFD was noted at amniocentesis. The pregnancy was subsequently terminated, and a 288-g female fetus was delivered with no phenotypic abnormalities. The umbilical cord had a karyotype of 46,XX (40/40 cells), and the placenta had a karyotype of 47,XX,+16 (40/40 cells). QF-PCR assays of the placenta confirmed a maternal origin of trisomy 16.ConclusionMosaic trisomy 16 at amniocentesis can be associated with positive NIPT for trisomy 16, placental trisomy 16, IUGR, IUFD, cytogenetic discrepancy between cultured amniocytes and uncultured amniocytes, and prenatal progressive decrease of the aneuploid cell line.     

Trisomy 7 mosaicism at amniocentesis: interphase FISH, QF-PCR, and aCGH analyses on uncultured amniocytes for rapid distinguishing of true mosaicism from pseudomosaicism

ObjectiveTo present prenatal diagnosis of true trisomy 7 mosaicism.Materials, Methods and ResultsA 36-year-old woman underwent amniocentesis at 18 weeks of gestation. Amniocentesis revealed a karyotype of 47,XY,+7[20]/46,XY[9]. The parental karyotypes were normal. Repeated amniocentesis was performed at 20 weeks of gestation. Array comparative genomic hybridization (aCGH) analysis on uncultured amniocytes manifested a genomic gain in chromosome 7. Quantitative fluorescent polymerase chain reaction (QF-PCR) analysis on uncultured amniocytes showed a biparental diallelic pattern with a dosage increase in the maternal allele. Interphase fluorescence in situ hybridization (FISH) on uncultured amniocytes revealed three 7q-specific signals in 13 of 50 (26%) of the cells. The cultured amniocytes had a karyotype of 47,XY,+7[12]/46,XY[14]. The ultrasound findings were unremarkable. The pregnancy was subsequently terminated, and a fetus was delivered with facial dysmorphisms. Postnatal tissue samplings revealed the mosaic trisomy 7 level of 37.5% (15/40), 30% (12/40), 42.5% (17/40), 82.5% (33/40), 52.5% (21/40), and 27.5% (11/40) in skin, liver, lungs, placenta, membrane, and cord, respectively. The cord blood had a karyotype of 46,XY. PEG1/MEST methylation-sensitive high-resolution melting PCR assay of cord blood showed no uniparental disomy for chromosome 7.ConclusionInterphase FISH, QF-PCR, and aCGH analyses on uncultured amniocytes are useful for rapid distinguishing of true mosaicism from pseudomosaicism for trisomy 7 at amniocentesis. Cord blood sampling for confirmation of fetal trisomy 7 mosaicism is not practical.     

Low-level mosaic trisomy 13 at amniocentesis in a pregnancy associated with a favorable fetal outcome and cytogenetic discrepancy in various tissues

ObjectiveWe present low-level mosaic trisomy 13 at amniocentesis in a pregnancy associated with associated with a favorable fetal outcome and cytogenetic discrepancy in various tissues.Case ReportA 38-year-old, gravida 3, para 0, woman underwent amniocentesis at 19 weeks of gestation because of advanced maternal age. This pregnancy was conceived by in vitro fertilization and embryo transfer. Amniocentesis revealed a karyotype of 47,XX,+13[2]/ 46,XX[20] in co-twin A and a karyotype of 46,XY in co-twin B. In co-twin A, among 22 colonies of cultured amniocytes, two colonies had a karyotype of 47,XX,+13, whereas the rest 20 colonies had the karyotype of 46,XX. Array comparative genomic hybridization (aCGH) analysis on the DNA extracted from cultured amniocytes revealed arr (1-22,X) × 2, Y × 0 and detected no genomic imbalance. Prenatal ultrasound and parental karyotypes were normal. Quantitative fluorescence polymerase chain reaction (QF-PCR) analysis on the DNA extracted from the parental bloods and cultured amniocytes excluded uniparental disomy (UPD) 13. The woman was encouraged to continue the pregnancy. At 37 weeks of gestation, a normal 2410-g female co-twin A and a normal 2360-g male co-twin B were delivered without any phenotypic abnormality. The karyotypes of cord blood, umbilical cord and placenta of co-twin A were 46,XX (40/40 cells), 47,XX,+13 [1]/46,XX[39] and 47,XX,+13[36]/46,XX [4], respectively. QF-PCR analysis on cord blood of co-twin A excluded UPD 13. When follow-up at age 1½ years, the neonate of co-twin A was normal in physical and psychomotor development.ConclusionLow-level true mosaic trisomy 13 at amniocentesis can be associated with a favorable fetal outcome and cytogenetic discrepancy in various tissues.     

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 of low-level mosaic trisomy 17 with maternal uniparental disomy 17 by amniocentesis in a pregnancy with a favorable outcome

ObjectiveWe present prenatal diagnosis low-level mosaic trisomy 17 with maternal uniparental disomy (UPD) 17 at amniocentesis in a pregnancy with a favorable outcome.Materials and methodsA 40-year-old, primigravid woman underwent amniocentesis at 18 weeks of gestation because of advanced maternal age. This pregnancy was conceived by in vitro fertilization and embryo transfer. Amniocentesis revealed a karyotype of 47,XX,+17 [13]/ 46, XX [23]. Repeat amniocentesis was performed at 21 weeks of gestation. Conventional cytogenetic analysis was applied on cultured amniocytes, parental bloods and cord blood. Simultaneous molecular genetic analysis such as interphase fluorescence in situ hybridization (FISH), array comparative genomic hybridization (aCGH) and quantitative fluorescent polymerase chain reaction (QF-PCR) assays were applied on uncultured amniocytes. Interphase FISH was applied on postnatal buccal cells.ResultsRepeat amniocentesis revealed a karyotype of 47,XX,+17[6]/46,XX[28]. Genetic analyses on uncultured amniocytes showed the results of mosaic trisomy 17 (12/101 cells = 11.9%) in FISH analysis, no genomic imbalance in aCGH analysis and maternal UPD 17 in QF-PCR assays. The parental karyotypes were normal. Prenatal ultrasound findings were unremarkable. The parents decided to continue the pregnancy, and a 1449-g, phenotypically normal female baby was delivered prematurely at 31 weeks of gestation. The cord blood had a karyotype of 46,XX. She had a normal psychomotor development at age 22 months at follow-up. Interphase FISH analysis on buccal cells showed trisomy 17 signals in 1/66 cells (1.5%).ConclusionsLow-level mosaicism for trisomy 17 associated with maternal UPD 17 detected by amniocentesis without ultrasound abnormality can be associated with a favorable outcome. Molecular genetic analysis of uncultured amniocytes at repeat amniocentesis is useful for confirmation and genetic counseling under such as circumstance.     

Prenatal diagnosis and molecular cytogenetic characterization of a small supernumerary marker chromosome derived from chromosome 15 in a pregnancy associated with recurrent Down syndrome

ObjectiveWe present prenatal diagnosis and molecular cytogenetic characterization of a small supernumerary marker chromosome (sSMC) derived from chromosome 15 in a pregnancy associated with recurrent Down syndrome.Case reportA 33-year-old, gravida 4, para 2, woman underwent amniocentesis at 16 weeks of gestation because of a previous child with Down syndrome and a karyotype of 46,XY,der(14;21)(q10; q10),+21. In this pregnancy, amniocentesis revealed a karyotype of 47,XX,+21[12]/48,XX,+21,+mar[3]. The parental karyotypes were normal. The pregnancy was terminated, and a malformed fetus was delivered with characteristic craniofacial appearance of Down syndrome and hypoplastic middle phalanx of the fifth fingers. The placenta had a karyotype of 47,XX,+21[37]/48,XX,+21,+mar[3]. The umbilical cord had a karyotype of 47,XX,+21[38]/48,XX,+21,+mar[2]. In addition to trisomy 21, array comparative genomic hybridization (aCGH) on the DNA extracted from umbilical cord revealed 40～50% mosaicism for a 2.604-Mb duplication of 15q25.2–q25.3, or arr 15q25.2q25.3 (83,229,665–85,834,131) × 2.4 [GRCh37 (hg19)] encompassing 19 Online Mendelian Inheritance in Man (OMIM) genes. Quantitative fluorescent polymerase chain reaction (QF-PCR) using the DNAs extracted from cultured amniocytes and parental bloods revealed maternal origin of the sSMC(15) and the extra chromosome 21.Conclusion: aCGH is useful for identification of the nature of sSMC, and QF-PCR is useful for determination of the parental origin of the aberrant chromosomes.     

Mosaic trisomy 21 at amniocentesis associated with a favorable fetal outcome and perinatal progressive decrease of the trisomy 21 cell line

ObjectiveWe present mosaic trisomy 21 at amniocentesis associated with a favorable fetal outcome and perinatal progressive decrease of the trisomy 21 cell line.Case reportA 33-year-old woman underwent elective amniocentesis at 17 weeks of gestation because of anxiety, and the karyotype of cultured amniocytes was 47,XX,+21[4]/46,XX[13]. In 17 colonies of cultured amniocytes, four colonies had 47,XX,+21, while the other 13 colonies had 46,XX. Simultaneous array comparative genomic hybridization (aCGH) analysis on uncultured amniocytes revealed the result of arr (21) × 3 [0.32] consistent with 32% mosaicism for trisomy 21. Repeat amniocentesis performed at 25 weeks of gestation revealed 47,XX,+21[4]/46,XX[24] with four colonies of 47,XX,+21 and 24 colonies of 46, XX on cultured amniocytes, and arr 21q11.2q22.3 × 2.25 by aCGH, 19.2% mosaicism for trisomy 21 (20/104 cells) by interphase fluorescence in situ hybridization (FISH), and no uniparental disomy (UPD) 21 by quantitative fluorescence polymerase chain reaction (QF-PCR) on uncultured amniocytes. The parental karyotypes were normal, and prenatal ultrasound was unremarkable. A phenotypically normal 2815-g female baby was delivered at 38 weeks of gestation. Cytogenetic analysis on the cord blood, umbilical cord and placenta revealed the karyotype of 47,XX,+21[10]/46,XX[30]. 47,XX,+21[5]/46,XX[35] and 47,XX,+21[38]/46,XX[2], respectively. QF-PCR analysis on the DNA extracted from parental bloods, uncultured amniocytes, cord blood, umbilical cord and placenta confirmed a paternal origin of trisomy 21. When follow-up at age two months, the neonate was phenotypically normal, the peripheral blood had a karyotype of 47,XX,+21[6]/46,XX[34], and no trisomy 21 signals by interphase FISH was found on 100 buccal mucosal cells. When follow-up at age 13 months, the neonate was phenotypically normal, and the peripheral blood had a karyotype of 47,XX,+21[3]/46,XX[37].ConclusionMosaic trisomy 21 at amniocentesis can be a transient and benign condition, and the abnormal trisomy 21 cell line may decrease and disappear after birth.     

Prenatal diagnosis and molecular cytogenetic characterization of a de novo deletion of 4q34.1→qter associated with low PAPP-A and low PlGF in the first-trimester maternal serum screening,congenital heart defect on fetal ultrasound and a false negative non-invasive prenatal testing (NIPT) result

ObjectiveWe present prenatal diagnosis and molecular cytogenetic characterization of a de novo deletion of 4q34.1→qter associated with low pregnancy associated plasma protein-A (PAPP-A) and low placental growth factor (PlGF) in the first-trimester maternal serum screening, congenital heart defect (CHD) on fetal ultrasound and a false negative non-invasive prenatal testing (NIPT) result.Case ReportA 40-year-old, primigravid woman underwent amniocentesis at 20 weeks of gestation because of advanced maternal age. This pregnancy was conceived by in vitro fertilization (IVF) and embryo transfer (ET). First-trimester maternal serum screening at 12 weeks of gestation revealed low PAPP-A [0.349 multiples of the median (MoM)] and low PlGF (0.299 MoM) and showed a risk for fetal trisomy 21 and trisomy 13. However, NIPT detected no genomic imbalance and a normal result. Nevertheless, level II ultrasound revealed ventricular septal defect, single umbilical artery and a small brain midline cyst. Amniocentesis revealed a karyotype of 46,XX,del(4)(q34.1) and a 17.8-Mb deletion of 4q34.1q.35.2 on array comparative genomic hybridization (aCGH) analysis. The parental karyotypes were normal. The pregnancy was terminated at 23 weeks of gestation, and a malformed fetus was delivered with craniofacial dysmorphism. Postnatal cytogenetic analysis of the placenta confirmed the prenatal diagnosis. There was a 17.8-Mb deletion of 4q34.1q.35.2 encompassing the genes of HAND2, SORBS2 and DUX4. Polymorphic DNA marker analysis on the parental bloods and cord blood showed a paternal origin of the deletion.ConclusionAn abnormal first-trimester maternal serum screening result along with abnormal fetal ultrasound should alert the possibility of fetal aneuploidy, and amniocentesis is indicated even in the presence of a normal NIPT result.     

Low-level mosaic trisomy 9 at amniocentesis in a pregnancy associated with a favorable fetal outcome,intrauterine growth restriction,cytogenetic discrepancy between cultured amniocytes and uncultured amniocytes and perinatal progressive decrease of the aneuploid cell line

ObjectiveWe present low-level mosaic trisomy 9 at amniocentesis in a pregnancy associated with a favorable fetal outcome, intrauterine growth restriction (IUGR), cytogenetic discrepancy between cultured amniocytes and uncultured amniocytes and perinatal progressive decrease of the aneuploid cell line.Case reportA 37-year-old, primigravid woman underwent amniocentesis at 17 weeks of gestation because of advanced maternal age. This pregnancy was conceived by in vitro fertilization and embryo transfer (IVF-ET). Amniocentesis revealed a karyotype of 47,XY,+9[11]/46,XY[32], and simultaneous array comparative genomic hybridization (aCGH) analysis on the DNA extracted from uncultured amniocytes revealed arr (X,Y) × 1, (1–22) × 2 without genomic imbalance. Prenatal ultrasound and parental karyotypes were normal. Repeat amniocentesis at 22 weeks of gestation revealed a karyotype of 47,XY,+9[5]/46,XY[19], and simultaneous aCGH analysis on the DNA extracted from uncultured amniocytes revealed arr 9p24.3q34.3 × 2.1 (log₂ ratio = 0.1) compatible with 10–15% mosaicism for trisomy 9. Quantitative fluorescence polymerase chain reaction (QF-PCR) assays excluded uniparental disomy (UPD) 9. A third amniocentesis at 29 weeks of gestation revealed a karyotype of 47,XY,+9[5]/46,XY[18], and simultaneous aCGH analysis on the DNA extracted from uncultured amniocytes revealed arr 9p24.3q34.3 × 2.1 (log₂ ratio = 0.1) compatible with 10–15% mosaicism for trisomy 9. Interphase fluorescent in situ hybridization (FISH) analysis on uncultured amniocytes revealed 9% (9/100 cells) mosaicism for trisomy 9. IUGR was noted on prenatal ultrasound. The pregnancy was carried to 38 weeks of gestation, and a 2375-g phenotypically normal male baby was delivered. The karyotypes of umbilical cord, cord blood and placenta were 46,XY (40/40 cells), 47,XY,+9[1]/46,XY[39] and 47,XY,+9[12]/46,XY[28], respectively. QF-PCR assays on placenta showed trisomy 9 of maternal origin. When follow-up at age two months, the neonate was normal in development. The peripheral blood had a karyotype of 46,XY (40/40 cells), and the buccal mucosal cells had 7.5% (8/106 cells) mosaicism for trisomy 9 by interphase FISH analysis.ConclusionLow-level mosaic trisomy 9 at amniocentesis can be associated with a favorable fetal outcome and cytogenetic discrepancy between cultured amniocytes and uncultured amniocytes.     

Monozygotic twins discordant for low-level mosaic trisomy 17 at amniocentesis in a pregnancy with a favorable outcome and a literature review of heterokaryotypic monozygotic twins at amniocentesis

ObjectiveWe present a set of twins discordant for low-level mosaic trisomy 17 at amniocentesis, and we review the literature of heterokaryotypic monozygotic twins at amniocentesis.Materials and methodsWe describe a monozygotic twin pregnancy with discordant karyotypes and structural abnormalities. A 22-year-old, primigravid woman underwent amniocentesis at 21 weeks of gestation because of an abnormal maternal serum screening result for Down syndrome. Prenatal ultrasound revealed twin-twin transfusion syndrome but no detectable fetal structural abnormalities. Conventional cytogenetic analysis was applied on cultured amniocytes and parental bloods. Polymorphic DNA marker analysis by quantitative fluorescent polymerase chain reaction (QF-PCR) testing was performed on the DNAs extracted from cultured amniocytes, parental bloods and peripheral bloods of the twins after birth. Interphase fluorescence in situ hybridization (FISH) analysis was performed on buccal mucosal epithelial cells.ResultsAmniocentesis revealed a karyotype of 47,XX,+17 [3]/46,XX [23] in twin A and a karyotype of 46,XX in twin B. The parental karyotypes were normal. QF-PCR confirmed monozygotic twinning and excluded uniparental disomy (UPD) 17. At 35 weeks of gestation, a 1778-g twin A and a 2396-g twin B were delivered smoothly. Both infants had the karyotype of 46,XX in the peripheral bloods and were phenotypically normal except that twin A had preaxial polydactyly on the right hand. Postnatal QF-PCR testing confirmed monozygotic twinning. The infants were doing well at age 2 years and 7 months at follow-ups with normal physical and psychomotor development. FISH analysis on buccal mucosal epithelial cells showed trisomy 17 signals in 4.16% (4/96) cells, compared with 5% (5/101 cells) in normal control.ConclusionsMonozygotic twins discordant for low-level mosaic trisomy 17 at amniocentesis without ultrasound abnormalities can have a favorable outcome. Prenatal diagnosis of twins discordant for structural abnormalities and/or chromosomal aberrations should alert the possibility of monozygotic twinning, and QF-PCR testing is useful for rapid determination of zygosity and exclusion of UPD under such a circumstance.     

Cytogenetic discrepancy between uncultured amniocytes and cultured amniocytes in mosaic trisomy 18 at amniocentesis in a pregnancy with a favorable fetal outcome and maternal uniparental disomy 18

ObjectiveWe present prenatal diagnosis of mosaic trisomy 18 in a pregnancy with a favorable fetal outcome and maternal uniparental disomy 18.Case reportA 38-year-old, primigravid woman underwent the first amniocentesis at 16 weeks of gestation because advanced maternal age. Amniocentesis revealed a karyotype of 46,XX [22/22] in cultured amniocytes, and 36% mosaicism for trisomy 18 and a maternally inherited Xp22.31 microdeletion by array comparative genomic hybridization (aCGH) in uncultured amniocytes. The second amniocentesis at 18 weeks of gestation revealed 47,XX,+18 [14]/46,XX [36] in cultured amniocytes and 36% mosaicism for trisomy 18 by multiplex ligation-dependent probe amplification (MLPA) P095 in cultured amniocytes. Prenatal ultrasound was normal. The parents were phenotypically normal. The third amniocentesis at 23 weeks of gestation revealed 47,XX,+18 [3]/46,XX [17] in cultured amniocytes, and in uncultured amniocytes, aCGH revealed 45%–50% mosaicism for trisomy 18, interphase fluorescence in situ hybridization (FISH) revealed 36% (36/100 cells) mosaicism for trisomy 18, and quantitative fluorescent polymerase chain reaction (QF-PCR) showed mosaic maternal uniparental heterodisomy for chromosome 18 and mosaic trisomy 18 of maternal origin. The fourth amniocentesis at 32 weeks of gestation revealed a karyotype of 46,XX [20/20] in cultured amniocytes, and in uncultured amniocytes, aCGH revealed 50%–60% mosaicism for trisomy 18, FISH revealed 21.8% (22/101 cells) mosaicism for trisomy 18, and non-invasive prenatal testing (NIPT) showed chromosome 18 gene dosage increase in the maternal blood. At 34 weeks of gestation, a 1480-g phenotypically normal baby was delivered. The cord blood had 47,XX,+18 [10]/46,XX [30]. The umbilical cord had 47,XX,+18 [4]/46,XX [36]. The placenta had 47,XX,+18 [40/40], and QF-PCR analysis confirmed trisomy 18 of maternal origin. When follow-up at age four months, the neonate was phenotypically normal, FISH analysis on buccal mucosal cells revealed 2% (2/100 cells) mosaicism for trisomy 18, and the peripheral blood had 47,XX,+18 [18]/46,XX [22]. When follow-up at age eight months, the neonate had normal development, the peripheral blood had 47,XX,+18 [15]/46,XX [25], and the buccal mucosal cells showed maternal uniparental heterodisomy for chromosome 18.ConclusionCytogenetic discrepancy may occur between uncultured and cultured amniocytes in mosaic trisomy 18 at amniocentesis. Cultured amniocytes may present progressive decrease in the levels of mosaicism for trisomy 18 as the fetus grows. Mosaic trisomy 18 at amniocentesis can be associated with a favorable outcome.