Cytogenetic discrepancy between uncultured amniocytes and cultured amniocytes in mosaic trisomy 15 at amniocentesis

ObjectiveWe present mosaic trisomy 15 at amniocentesis.Materials and methodsA 41-year-old woman underwent amniocentesis at 16 weeks of gestation because of an abnormal non-invasive prenatal testing (NIPT) result suspicious of trisomy 15. Amniocentesis revealed a karyotype of 46,XY. Array comparative genomic hybridization (aCGH) on uncultured amniocytes revealed 26% mosaicism for trisomy 15. She was referred for repeat amniocentesis. aCGH, interphase fluorescence in situ hybridization (FISH), quantitative fluorescent polymerase chain reaction (QF-PCR) assays and/or conventional cytogenetic analysis were applied on various cells and tissues including uncultured amniocytes, cultured amniocytes, cord blood, placenta, parental bloods and/or buccal mucosal cells.ResultsRepeat amniocentesis at 21 weeks of gestation revealed a karyotype of 46, XY in cultured amniocytes, and 30% mosaicism for trisomy 15 by aCGH and 32% mosaicism for trisomy 15 by FISH in uncultured amniocytes. Repeat amniocentesis at 29 weeks of gestation revealed a karyotype of 46, XY in cultured amniocytes, and 15% mosaicism for trisomy 15 by aCGH and 7.2% mosaicism for trisomy 15 by FISH in uncultured amniocytes. QF-PCR on cultured amniocytes excluded uniparental disomy (UPD) 15. A phenotypically normal baby was delivered subsequently with a karyotype of 46, XY in cord blood and 2% mosaicism for trisomy 15 by FISH in buccal mucosal cells. The aCGH analysis revealed trisomy 15 in placenta and no genomic imbalance in cord blood. QF-PCR assays determined a maternal origin of trisomy 15 in placenta.ConclusionCytogenetic discrepancy may occur between uncultured and cultured amniocytes in mosaic trisomy 15 at amniocentesis. The cells of trisomy 15 cell line in prenatally detected mosaic trisomy 15 may decrease in number as the fetus grows. Whenever NIPT suspects trisomy 15, a confirmatory amniocentesis should include genetic analysis on both uncultured and cultured amniocytes to exclude mosaic trisomy 15 and maternal UPD 15, especially when the cultured amniocytes have a normal karyotype.     

Cytogenetic discrepancy between uncultured amniocytes and cultured amniocytes in mosaic trisomy 15 at amniocentesis in a pregnancy with a favorable outcome

ObjectiveWe present prenatal diagnosis of mosaic trisomy 15 in a pregnancy with a favorable outcome.Case reportA 33-year-old, primigravid woman underwent amniocentesis at 19 weeks of gestation because non-invasive prenatal testing (NIPT) revealed gene dosage increase at chromosome 15. Cytogenetic analysis revealed a karyotype of 47,XX,+15[10]/46,XX[13]. Using uncultured amniocytes, array comparative genomic hybridization (aCGH) revealed arr [GRCh37] (X) × 2, (15) × 3 [0.75], multiplex ligation-dependent probe amplification (MLPA) analysis showed rsa [GRCh36] 15q11q13 (21,362,818–27,196,819) × 3 [0.76] and methylation-specific (MS)-MLPA analysis showed a methylation index = 0.41 with paternal gene dosage increase at 15q11-q13. Repeat amniocentesis at 25 weeks of gestation revealed a karyotype of 47,XX,+15[6]/46,XX[14]. Using uncultured amniocytes, quantitative fluorescent polymerase chain reaction (QF-PCR) assays excluded uniparental disomy (UPD) 15 and determined a paternal origin of the extra chromosome 15, aCGH analysis showed 75%–80% mosaicism for trisomy 15, and interphase fluorescence in situ hybridization (FISH) showed 45.5% (46/101 cells) mosaicism for trisomy 15. Repeat amniocentesis at 28 weeks of gestation revealed a karyotype of 47,XX,+15[2]/46,XX[23]. Using uncultured amniocytes, aCGH showed 75–80% mosaicism for trisomy 15, and FISH showed 70.6% (72/102 cells) mosaicism for trisomy 15. Using cultured amniocytes, QF-PCR assays excluded UPD 15. Cordocentesis at 30 weeks of gestation revealed a karyotype of 47,XX,+15[2]/46,XX[138]. Using cord blood, aCGH revealed 9% gene dosage increase at chromosome 15, and MS-MLPA analysis excluded UPD 15. At 36 weeks of gestation, a 2060-g phenotypically normal baby was delivered. The cord blood had 46, XX (40/40 cells). The placenta had 47,XX,+15 (40/40 cells). QF-PCR analysis on placenta showed a paternal origin of trisomy 15. FISH analysis on buccal mucosal cells at age 20 days showed 20% (20/100 cells) mosaicism for trisomy 15.ConclusionCytogenetic discrepancy may occur between uncultured and cultured amniocytes in mosaic trisomy 15 at amniocentesis. Cultured amniocytes may present progressive decrease in the levels of mosaicism for trisomy 15 as the fetus grows. Mosaic trisomy 15 at amniocentesis without UPD 15 can be associated with a favorable outcome.     

Prenatal diagnosis of maternal uniparental disomy 16 associated with mosaic trisomy 16 at amniocentesis,and pericardial effusion and intrauterine growth restriction in the fetus

ObjectiveWe present prenatal diagnosis of maternal uniparental disomy (UPD) 16 associated with mosaic trisomy 16 at amniocentesis, and pericardial effusion and intrauterine growth restriction (IUGR) in the fetus.Case reportA 38-year-old woman underwent amniocentesis at 17 weeks of gestation because of advanced maternal age, and the result was 47,XX,+16[2]/46,XX[54]. Simultaneous array comparative genomic hybridization (aCGH) analysis on the DNA extracted from uncultured amniocytes revealed 14% mosaicism for trisomy 16 and a paternally inherited 319-kb microdeletion of 15q11.2 encompassing the genes of TUBGCP5, CYFIP1, NIPA2 and NIPA1. Prenatal ultrasound revealed persistent left superior vena cava, pericardial effusion and severe IUGR. Cordocentesis at 23 weeks of gestation revealed a karyotype of 46,XX, but polymorphic DNA marker analysis revealed maternal UPD 16. Repeat amniocentesis was performed at 27 weeks of gestation and revealed a karyotype of 46, XX in 21/21 colonies. Molecular cytogenetic analysis on uncultured amniocytes revealed 22.4% mosaicism (26/116 cells) for trisomy 16 on interphase fluorescence in situ hybridization (FISH) analysis, and 20% mosaicism for trisomy 16 on aCGH. Polymorphic DNA marker analysis on the DNAs extracted from uncultured amniocytes and parental bloods revealed maternal UPD 16. The pregnancy was subsequently terminated, and a fetus was delivered with facial dysmorphism and severe IUGR. The umbilical cord had a karyotype of 47,XX,+16[28]/46,XX[16]. Polymorphic DNA marker analysis on placenta confirmed a maternal origin of trisomy 16.ConclusionCytogenetic discrepancy between cultured amniocytes and uncultured amniocytes may present in mosaic trisomy 16 at amniocentesis. Prenatal diagnosis of mosaic trisomy 16 should alert the association of maternal UPD 16 which may be associated with congenital heart defects and severe IUGR on prenatal ultrasound.     

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.     

Low-level mosaicism for trisomy 16 at amniocentesis in a pregnancy associated with intrauterine growth restriction and a favorable outcome

ObjectiveWe present low-level mosaicism for trisomy 16 at amniocentesis in a pregnancy associated with intrauterine growth restriction (IUGR) and a favorable outcome.Case reportA 31-year-old woman underwent amniocentesis at 24 weeks of gestation because of IUGR. Amniocentesis revealed a karyotype of 47,XX,+16 [3]/46,XX [22]. Simultaneous array comparative genomic hybridization (aCGH) analysis on the DNA extracted from uncultured amniocytes revealed gene dosage increase in chromosome 16 consistent with 28% mosaicism for trisomy 16. Uniparental disomy (UPD) 7 and UPD 11 were excluded. She underwent repeat amniocentesis at 27 weeks of gestation. Repeat amniocentesis revealed a karyotype of 47,XX,+16 [1]/46,XX [24]. Simultaneous aCGH analysis on the DNA extracted from uncultured amniocytes revealed 25%–35% (log₂ ratio = 0.17–0.25) mosaicism for trisomy 16. Interphase fluorescence in situ hybridization (FISH) analysis detected trisomy 16 signals in 28/100 (28%) uncultured amniocytes. Polymorphic DNA marker analysis excluded UPD 16. Level II ultrasound revealed no fetal abnormalities except symmetric IUGR. The pregnancy was continued to 37 weeks of gestation, and a 2306-g phenotypically normal baby was delivered. The cord blood had a karyotype of 46, XX in 50/50 lymphocytes. The umbilical cord had a karyotype of 47,XX,+16 [14]/46,XX [36]. Interphase FISH analysis on buccal mucosal cells and urinary cells at age three days revealed trisomy 16 signals in 3.8% (4/106) buccal mucosal cells and 6.5% (7/107) urinary cells, compared with 1% in the normal control. Polymorphic DNA marker analysis on placenta confirmed trisomy 16 in the placenta and a maternal origin of the extra chromosome 16.ConclusionCytogenetic discrepancy between cultured amniocytes and uncultured amniocytes may present in mosaic trisomy 16 at amniocentesis. Low-level mosaicism for trisomy 16 at amniocentesis without maternal UPD 16 can be associated with a favorable outcome despite the presence of IUGR.     

Mosaic trisomy 22 at amniocentesis: Prenatal diagnosis and literature review

ObjectiveWe present prenatal diagnosis of mosaic trisomy 22 at amniocentesis in a pregnancy with facial cleft, oligohydramnios and intrauterine growth restriction (IUGR), and we review the literature.Case reportA 37-year-old woman underwent amniocentesis at 19 weeks of gestation because of advanced maternal age. Amniocentesis revealed a karyotype of 47,XX,+22[9]/46,XX[9]. Array comparative genomic hybridization (aCGH) analysis on uncultured amniocytes showed a result of arr(22) × 3 [0.8]. Prenatal ultrasound revealed fetal median facial cleft, oligohydramnios and IUGR. Repeat amniocentesis at 22 weeks of gestation using uncultured amniocytes revealed an aCGH result of arr 22q11.1q13.33 (17,397,498–51,178,264) × 2.8 compatible with 80% mosaicism for trisomy 22, and a fluorescence in situ hybridization (FISH) result of mosaic trisomy 22 with trisomy 22 in 54/100 interphase cells. The cultured amniocytes at repeat amniocentesis had a karyotype of 47,XX,+22[12]/46,XX[8]. The parental karyotypes were normal. Polymorphic DNA marker analysis confirmed a maternal origin of the extra chromosome 22. The pregnancy was terminated, and a 256-g female fetus was delivered with facial dysmorphism and median facial cleft. Cytogenetic analysis of the skin fibroblasts revealed a karyotype of 47,XX,+22[33]/46,XX[7].ConclusionFetuses with high level mosaicism for trisomy 22 at amniocentesis may present IUGR, facial cleft and oligohydramnios on prenatal ultrasound.     

Prenatal diagnosis of mosaic trisomy 16 by amniocentesis in a pregnancy associated with abnormal first-trimester screening result (low PAPP-A and low PlGF), intrauterine growth restriction and a favorable outcome

ObjectiveWe present prenatal diagnosis of mosaic trisomy 16 by amniocentesis in a pregnancy associated with an abnormal first-trimester screening result, intrauterine growth restriction (IUGR) and a favorable outcome.Case reportA 27-year-old woman underwent amniocentesis at 18 weeks of gestation because of an abnormal first-trimester screening result with maternal serum free β-hCG of 1.474 multiples of the median (MoM), pregnancy associated plasma protein-A (PAPP-A) of 0.122 MoM and placental growth factor (PlGF) of 0.101 MoM, and a Down syndrome risk of 1/45. Amniocentesis revealed a karyotype of 47,XY,+16 [9]/46,XY [16] and an abnormal array comparative genomic hybridization (aCGH) result of arr (16) × 3 [0.54] compatible with 54% mosaicism for trisomy 16 in uncultured amniocytes. At 24 weeks of gestation, repeat amniocentesis revealed a karyotype of 47,XY,+16 [4]/46,XY [16] and an aCGH result of arr 16p13.3q24.3 (96,766–90,567,357) × 2.25 with a log₂ ratio = 0.2 compatible with 20–30% mosaicism for trisomy 16 in uncultured amniocytes. Quantitative fluorescent polymerase chain reaction (QF-PCR) excluded uniparental disomy (UPD) 16. Interphase fluorescence in situ hybridization (FISH) analysis on uncultured amniocytes revealed 19.4% (12/62 cells) mosaic trisomy 16. Prenatal ultrasound revealed IUGR. At 36 weeks of gestation, a phenotypically normal baby was delivered with a body weight of 1900 g. The cord blood had a karyotype of 46,XY. QF-PCR analysis confirmed biparentally inherited disomy 16 in the cord blood and maternal-origin of trisomy 16 in the placenta. When follow-up at age two months, FISH analysis on 101 buccal mucosal cells and 32 urinary cells revealed no signal of trisomy 16.ConclusionMosaic trisomy 16 at amniocentesis can be associated with IUGR and an abnormal first-trimester screening result with low PAPP-A and low PlGF. Mosaic trisomy 16 without UPD 16 at amniocentesis can have a favorable outcome, and the abnormal triosmy 16 cell line may disappear after birth.     

Detection of maternal uniparental disomy 9 in association with low-level mosaic trisomy 9 at amniocentesis in a pregnancy associated with intrauterine growth restriction,abnormal first-trimester screening result (low PAPP-A and low PlGF), maternal preeclampsia and a favorable outcome

ObjectiveWe present detection of maternal uniparental disomy (UPD) 9 in association with low-level mosaic trisomy 9 at amniocentesis in a pregnancy associated with intrauterine growth restriction (IUGR), an abnormal first-trimester maternal serum screening result, abnormal non-invasive prenatal testing (NIPT), maternal preeclampsia and a favorable outcome.Case reportA 37-year-old, primigravid woman underwent first-trimester maternal serum screening and NIPT at 11 weeks of gestation, which revealed a gene dosage increase in chromosome 9 and low levels of plasma protein-A (PAPP-A) and placental growth factor (PlGF) in maternal blood. The woman underwent amniocentesis at 16 weeks of gestation, which revealed a karyotype of 47,XX,+9[4]/46,XX[35] in cultured amniocytes. Simultaneous array comparative genomic hybridization (aCGH) analysis on uncultured amniocytes revealed a result of arr [GRCh37] (9) × 3 [0.14] (X) × 2, compatible with mosaic trisomy 9. The parental karyotypes were normal. Repeat amniocentesis was performed at 20 weeks of gestation. The cultured amniocytes had a karyotype of 47,XX,+9[1]/46,XX[23]. The uncultured amniocytes had a mosaic trisomy 9 level of 10.7% (12/112 cells) by interphase fluorescence in situ hybridization (FISH), a mosaic trisomy 9 level of 10–14% (log₂ ratio = 0.1) by aCGH, and maternal uniparental isodisomy 9 by polymorphic DNA marker analysis. Prenatal ultrasound revealed IUGR, and the mother had preeclampsia. At 29 weeks of gestation, a 1054-g phenotypically normal baby was delivered because of preterm labor. The cord blood and umbilical cord had the karyotype of 46, XX and maternal UPD 9 and isodisomy 9, while the placenta had trisomy 9 of maternal origin. Postnatal FISH anlaysis on 101 buccal mucosal cells and 100 urinary cells at age three months detected no trisomy 9 signals. The baby was doing well at age six months.ConclusionPregnancy with low-level mosaic trisomy 9 and maternal UPD 9 at amniocentesis can be associated with IUGR, maternal preeclampsia and a favorable outcome. Fetuses with maternal UPD 9 can be associated with an abnormal NIPT result concerning chromosome 9, an abnormal first-trimester maternal serum screening result (low PAPP-A and low PlGF) and mosaic trisomy 9 at amniocentesis.     

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.     

Cytogenetic discrepancy between cultured amniocytes and uncultured amniocytes in mosaic trisomy 20 at amniocentesis in a pregnancy with a favorable outcome

ObjectiveWe present our observation of cytogenetic discrepancy between cultured amniocytes and uncultured amniocytes in mosaic trisomy 20 at amniocentesis in a pregnancy with a favorable outcome.Case reportA 35-year-old woman underwent amniocentesis at 16 weeks of gestation because of advanced maternal age. Amniocentesis revealed a karyotype of 47,XX,+20[10]/46,XX[15]. Among 25 colonies of cultured amniocytes, 10 colonies had a karyotype of 47,XX,+20, while the rest were normal. Simultaneous array comparative genomic hybridization (aCGH) analysis on the DNA extracted from uncultured amniocytes revealed no genomic imbalance, or arr (1–22,X) × 2. The parental karyotypes were normal. Following genetic counseling, the woman underwent repeat amniocentesis at 20 weeks of gestation. Repeat amniocentesis revealed a karyotype of 47,XX,+20[3]/46,XX[35]. Among 38 colonies of cultured amniocytes, three colonies had a karyotype of 47,XX,+20, while the rest were normal. Simultaneous aCGH analysis on the DNA extracted from uncultured amniocytes revealed no genomic imbalance, or arr (1–22,X) × 2. Interphase fluorescence in situ hybridization analysis on 101 uncultured amniocytes detected only one cell with three chromosome 20 signals with a mosaic trisomy 20 level of 1% (1/101 cells), compared with 0% in normal control. Polymorphic DNA marker analysis on the DNA extracted from uncultured amniocytes and parental bloods excluded uniparental disomy 20. At 38 weeks of gestation, a phenotypically normal 3120-g female baby was delivered. Cytogenetic analysis of cord blood, placental tissue and umbilical cord revealed a karyotype of 46,XX. The neonate was normal at postnatal follow-ups. Postnatal interphase fluorescence in situ hybridization analysis on 100 buccal mucosal cells revealed no trisomy 20 signals.ConclusionMosaic trisomy 20 at amniocentesis can be a cultured artifact. Complete cytogenetic discrepancy may occur between cultured amniocytes and uncultured amniocytes in mosaic trisomy 20 at amniocentesis, and molecular cytogenetic analysis on uncultured amniocytes is useful for rapid distinguishing true mosaicism from pseudomosaicism under such as circumstance.     

Mosaic trisomy 18 at amniocentesis associated with a favorable fetal outcome in a pregnancy

ObjectiveWe present prenatal diagnosis of mosaic trisomy 18 by amniocentesis associated with a favorable fetal outcome in a pregnancy.Case reportA 42-year-old, gravida 4, para 2, woman underwent amniocentesis at 18 weeks of gestation because advanced maternal age. Amniocentesis revealed a karyotype of 47,XX,+18[6]/46,XX[17]. Simultaneous array comparative genomic hybridization (aCGH) on uncultured amniocytes showed the result of 45% mosaicism for trisomy 18. At 25 weeks of gestation, the woman underwent repeat amniocentesis which revealed a karyotype of 47,XX,+18[10]/46,XX[24]. Simultaneous aCGH on uncultured amniocytes showed the result of arr 18p11.32q23 (148,963–78,012,829) × 2.3 [GRCh (hg19)] with a log₂ ratio of 0.2–0.25 compatible with 30–38% mosaicism for trisomy 18. The parental karyotypes were normal. Prenatal ultrasound was unremarkable. Interphase fluorescence in situ hybridization (FISH) on uncultured amniocytes showed 27% (27/100 cells) mosaicism for trisomy 18. Quantitative fluorescent polymerase chain reaction (QF-PCR) on uncultured amniocytes excluded uniparental disomy (UPD) 18. Non-invasive prenatal testing (NIPT) analysis at 34 weeks of gestation revealed a significant gene dosage increase of chromosome 18 (29.95; normal control: ?3.0–3.0). At 39 weeks of gestation, a 2840-g phenotypically normal baby was delivered. The cord blood had a karyotype of 47,XX,+18[8]/46,XX[32]. The placenta was trisomy 18 of maternal origin. The umbilical cord had a karyotype of 47,XX,+18[2]/46,XX[38]. At age 1½ months, the peripheral blood had a karyotype of 47,XX,+18[5]/46,XX[35], and FISH analysis on buccal mucosal cells revealed 2% (2/102 cells) mosaicism for trisomy 18. When follow-up at age seven months, the neonate was phenotypically normal, and the peripheral blood had a karyotype of 47,XX,+18[1]/46,XX[39].ConclusionsMosaic trisomy 18 at amniocentesis without abnormal fetal ultrasound can be associated with a favorable outcome, and the abnormal trisomy 18 cell line may decrease progressively after birth.     

Mosaic trisomy 12 at amniocentesis: Prenatal diagnosis and molecular genetic analysis

ObjectiveThis study is aimed at prenatal diagnosis of mosaic trisomy 12 and reviewing the literature.Materials and MethodsA 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,+12[9]/46,XX[14]. She was referred to the hospital for genetic counseling. Repeated amniocentesis was performed at 22 weeks of gestation. Array comparative genomic hybridization (aCGH), interphase fluorescence in situ hybridization (FISH) and quantitative fluorescent polymerase chain reaction (QF-PCR) were applied on uncultured amniocytes, and conventional cytogenetic analysis was applied on cultured amniocytes.ResultsThe aCGH analysis on uncultured amniocytes revealed a small genomic gain in chromosome 12. Interphase FISH analysis on uncultured amniocytes using a 12q11-q12-specific probe of RP11-496H24 (green spectrum) showed three green signals in 17.8% (8/45 cells) of uncultured amniocytes. QF-PCR analysis on uncultured amniocytes using chromosome 12-specific microsatellite markers excluded uniparental disomy 12. Cytogenetic analysis of cultured amniocytes revealed a karyotype of 47,XX,+12[5]/46,XX[25]. The parents decided to continue the pregnancy. A healthy 3270 g female baby was delivered at 39 weeks of gestation, with no phenotypic abnormalities. Cytogenetic analysis of the cord blood revealed a karyotype of 46,XX in 40/40 cultured lymphocytes. The neonate was normal in growth and psychomotor development at 6 months of age. Interphase FISH analysis on uncultured urinary cells revealed 5% (1/20 cells) mosaicism for trisomy 12.ConclusionPrenatal diagnosis of mosaic trisomy 12 at amniocentesis should alert a clinically significant aneuploidy. Interphase FISH and aCGH on uncultured amniocytes are useful for rapid confirmation of low-level trisomy 12 mosaicism at repeated amniocentesis.     

Low-level mosaic trisomy 21 at amniocentesis in a pregnancy associated with a negative NIPT result,cytogenetic discrepancy in various tissues,perinatal progressive decrease of the aneuploid cell line and a favorable fetal outcome

ObjectiveWe present low-level mosaic trisomy 21 at amniocentesis associated with a favorable fetal outcome.Case reportA 31-year-old primigravid woman underwent non-invasive prenatal testing (NIPT) at 12 weeks of gestation, and the result was normal. She underwent amniocentesis at 16 weeks of gestation because of fetal choroid plexus cyst, and the result was 47,XX,+21[5]/46,XX[32]. Repeat amniocentesis was performed at 19 weeks of gestation, and the result was 47,XX,+21[5]/46,XX[15]. Simultaneous array comparative genomic hybridization (aCGH) analysis on uncultured amniocytes revealed the result of arr (21) × 3 [0.10], consistent with 10% mosaicism for trisomy 21. Prenatal ultrasound findings were unremarkable. She was referred for genetic counseling at 22 weeks of gestation, and the third amniocentesis was performed at 25 weeks of gestation, and the result was 46,XX (20/20 colonies). The parental karyotypes were normal. Simultaneous quantitative fluorescence polymerase chain reaction (QF-PCR) analysis on the DNA extracted from uncultured amniocytes and parental bloods excluded uniparental disomy (UPD) 21. aCGH analysis on uncultured amniocytes revealed arr 21q11.2q22.3 × 2.1 (log₂ ratio = 0.1), consistent with 10–15% mosaicism for trisomy 21. Fluorescence in situ hybridization (FISH) analysis on uncultured amniocytes revealed 30% (30/100 cells) mosaicism for trisomy 21. The woman was advised to continue the pregnancy, and a phenotypically normal 2800-g female baby was delivered at 38 weeks of gestation. The karyotype of cord blood, umbilical cord and placenta were 47,XX,+21[1]/46,XX[39]. 47,XX,+21[4]/46,XX[36] and 46,XX (40/40 cells), respectively. When follow-up at age two months, the neonate was phenotypically normal. The peripheral blood had a karyotype of 47,XX,+21[1]/46,XX[39], and FISH analysis on buccal mucosal cells revealed 8.4% (7/83 cells) mosaicism for trisomy 21, compared with 0% in the normal control.ConclusionLow-level mosaic trisomy 21 at amniocentesis can be associated with a negative NIPT result, cytogenetic discrepancy in various tissues, perinatal progressive decrease of the aneuploid cell line and a favorable fetal outcome.     

Cytogenetic discrepancy between cultured amniocytes and uncultured amniocytes in mosaic double trisomy involving trisomy 7 and trisomy 20 (48,XY,+7,+20) at amniocentesis

ObjectiveWe present mosaic double trisomy involving trisomy 7 and trisomy 20 at amniocentesis in a pregnancy with a favorable outcome.Case reportA 41-year-old woman underwent amniocentesis at 16 weeks of gestation because of advanced maternal age. Amniocentesis revealed a result of 48,XY,+7,+20[6]/46,XY[26] in cultured amniocytes. At 19 weeks of gestation, repeat amniocentesis was performed, which revealed a result of 48,XY,+7,+20[4]/46,XY[21] in cultured amniocytes. Simultaneous molecular cytogenetic analyses on uncultured amniocytes at repeat amniocentesis revealed no genomic imbalance in array comparative genomic hybridization (aCGH) analysis, no trisomy 7 and no trisomy 20 signals in 114/114 cells in interphase fluorescence in situ hybridization (FISH) analysis, and no uniparental disomy (UPD) 7 and no UPD 20 in quantitative fluorescent polymerase chain reaction (QF-PCR) analysis. Interphase FISH analysis on cultured amniocytes revealed double trisomy of trisomy 7 and trisomy 20 in 5/105 cells (4.7%) compared with 0/100 cells (0%) in the normal control. Prenatal ultrasound findings were unremarkable. The parental karyotypes were normal. The woman decided to continue the pregnancy, and a healthy 2880-g phenotypically normal male baby was delivered at 34 weeks of gestation without any structural abnormality. The cord blood had a normal karyotype. Interphase FISH analysis of the urinary cells revealed no trisomy 7 and no trisomy 20 signals in 51/51 urinary cells.ConclusionCytogenetic discrepancy between cultured amniocytes and uncultured amniocytes can occur in mosaicism for double trisomy involving trisomy 7 and trisomy 20 at amniocentesis. Molecular cytogenetic analyses such as aCGH, FISH and QF-PCR on uncultured amniocytes are useful for rapid distinguishing true mosaicism from pseudomosaicism under such a circumstance.     

Prenatal diagnosis of pseudomosaicism for trisomy 20 at amniocentesis with a negative non-invasive prenatal testing (NIPT) result in a pregnancy with a favorable outcome

ObjectiveWe present prenatal diagnosis of pseudomosaicism for trisomy 20 at amniocentesis with a negative non-invasive prenatal testing (NIPT) result in a pregnancy with a favorable outcome.Case reportA 33-year-old, primigravid woman underwent amniocentesis at 17 weeks of gestation, which revealed a karyotype of 47,XX,+20[8]/46,XX[31]. Simultaneous array comparative genomic hybridization (aCGH) analysis on the DNA extracted from uncultured amniocytes revealed the result of arr (1–22,X) × 2, consistent with no genomic imbalance. She was referred to the hospital for repeat amniocentesis at 23 weeks of gestation. At repeat amniocentesis, cultured amniocytes had a karyotype of 47,XX,+20[2]/46,XX[33]. The parental karyotypes were normal. Simultaneous aCGH analysis on the DNA extracted from uncultured amniocytes using SurePrint G3 Unrestricted CGH ISCA v2, 8 × 60 K (Agilent Technologies, Santa Clara, CA, USA) revealed no genomic imbalance, or arr (1–22,X) × 2, Y × 0. Interphase fluorescence in situ hybridization (FISH) analysis using the bacterial artificial chromosome (BAC) probes of RP11-266K16 [20q13.33; fluorescein isothiocyanate (FITC), spectrum green] and RP11-348I14 (20q11.1-q11.21; Texas Red, spectrum red) detected trisomy 20 signals in 4/104 uncultured amniocytes (3.8%), compared with 0/100 in the normal control. Polymorphic DNA marker analysis using the DNA extracted from uncultured amniocytes and parental bloods excluded uniparental disomy 20. NIPT analysis on maternal blood revealed a negative result without gene dosage increase in chromosome 20. The pregnancy was carried to term, and a healthy 2830-g female baby was delivered with no phenotypic abnormality. Both cord blood and placenta had a karyotype of 46,XX.ConclusionNIPT is useful for rapid differential diagnosis of pseudomosaicism from true mosaicism in case of mosaic trisomy 20 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 mosaicism for double trisomies of trisomy 11 and trisomy 12 in a single colony at amniocentesis in a pregnancy with a favorable outcome

ObjectiveWe present prenatal diagnosis of mosaicism for double trisomies of trisomy 11 and trisomy 12 in a single colony at amniocentesis with a favorable outcome.Case reportA 23-year-old woman underwent amniocentesis at 24 weeks of gestation because of congenital bowel dilation in the fetus. Amniocentesis revealed a karyotype of 48,XX,+11,+12[1]/46,XX[24]. In 25 colonies of cultured amniocytes, all five cells in one colony had the karyotype of 48,XX,+11,+12, while the rest 24 colonies had the karyotype of 46,XX. The parental karyotypes were normal. Repeat amniocentesis was performed at 26 weeks of gestation. Interphase fluorescence in situ hybridization (FISH), array comparative genomic hybridization (aCGH) and quantitative fluorescent polymerase chain reaction (QF-PCR) were applied on the uncultured amniocytes, and conventional cytogenetic analysis was applied on cultured amniocytes. Interphase FISH analysis showed no trisomy 11 signal and no trisomy 12 signal in 102 uncultured amniocytes. QF-PCR analysis excluded uniparental disomy (UPD) 11 and UPD 12. aCGH analysis showed no genomic imbalance. The cultured amniocytes at repeat amniocentesis had the karyotype of 46,XX in 13/13 colonies. At term, a healthy 3445-g female baby was delivered with no phenotypic abnormality except imperforate anus and a perianal fistula. The cord blood had a karyotype of 46,XX in 40/40 lymphocytes. Postnatal interphase FISH analysis of buccal cells and urinary cells revealed trisomies 11 and 12 signals in 11/111 (9.9%) buccal cells compared with 3% in normal control, and in 3/103 (2.9%) urinary cells compared with 0.98% in normal control.ConclusionMosaicism for double trisomies of trisomy 11 and trisomy 12 in a single colony at amniocentesis without UPD 11 and UPD 12 can be associated with a favorable outcome.     

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 of maternal uniparental disomy 21 in association with low-level mosaic trisomy 21 at amniocentesis in a pregnancy associated with intrauterine growth restriction and a favorable outcome

ObjectiveWe present prenatal diagnosis of maternal uniparental disomy (UPD) 21 in association with low-level mosaic trisomy 21 at amniocentesis in a pregnancy associated with intrauterine growth restriction (IUGR) and a favorable outcome.Case reportA 42-year-old, gravida 2, para 0, woman underwent amniocentesis at 17 weeks of gestation because of advanced maternal age. Amniocentesis initially revealed a karyotype of 46,XX in 20/20 colonies of cultured amniocytes. Simultaneous array comparative genomic hybridization (aCGH) analysis on uncultured amniocytes revealed a result of arr [GRCh37] (21) × 3 [0.16], (X) × 2, compatible with mosaic trisomy 21. After extensive investigation, the final result of conventional cytogenetic analysis of cultured amniocytes was 47,XX,+21[1]/46,XX[40]. The parental karyotypes were normal. Repeat amniocentesis was performed at 21 weeks of gestation. The cultured amniocytes had a karyotype of 47,XX,+21[3]/46,XX[27] and the uncultured amniocytes had a mosaic trisomy 21 level of 8.8% (10/114 cells) by interphase fluorescence in situ hybridization (FISH), a mosaic trisomy 21 level of 10% (log₂ ratio = 0.08) by aCGH, and maternal UPD 21 by polymorphic DNA marker analysis. Prenatal ultrasound revealed IUGR. At 38 weeks of gestation, a phenotypically normal 2695-g baby was delivered. The cord blood and umbilical cord had the karyotype of 46,XX and maternal UPD 21. The placenta had a karyotype of 47,XX,+21[8]/46,XX[32] and a maternal origin of trisomy 21. Postnatal FISH analysis on 101 buccal mucosal cells showed 6.9% (7/101 cells) mosaicism compared with 2% (2/100 cells) in the normal control. The baby was doing well at age four months.ConclusionPregnancy with low-level mosaic trisomy 21 and maternal UPD 21 at amniocentesis can be associated with IUGR and a favorable outcome. Fetuses with maternal UPD 21 can be associated with mosaic trisomy 21 at amniocentesis.     

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.