Prenatal diagnosis and molecular cytogenetic characterization of mosaicism for a small supernumerary marker chromosome derived from chromosome 16

Objective

We present prenatal diagnosis and molecular cytogenetic characterization of a small supernumerary marker chromosome (sSMC) derived from chromosome 16.

Prenatal diagnosis and molecular cytogenetic characterization of mosaicism for a small supernumerary marker chromosome derived from chromosome 21q11.2-q21.1 and a literature review

Objective

We present prenatal diagnosis and molecular cytogenetic characterization of mosaicism for a small supernumerary marker chromosome (sSMC) derived from chromosome 21q11.2-q21.1, and we review the literature of an sSMC(21) with a duplication of 21q11.2-q21.1.

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.     

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.     

Cytogenetic discrepancy between cultured amniocytes and uncultured amniocytes in mosaic 46,XX,dup(9)(q22.3q34.1)/46,XX at amniocentesis in a pregnancy with a favorable outcome

ObjectiveWe present our observation of cytogenetic discrepancy between cultured amniocytes and uncultured amniocytes in mosaic dup(9)(q22.3q34.1) at amniocentesis in a pregnancy with a favorable outcome.Case reportA 37-year-old, gravida 4, para 0, woman underwent amniocentesis at 18 weeks of gestation because of advanced maternal age. Amniocentesis revealed a karyotype of 46,XX, dup(9)(q22.3q34.1)[8]/46,XX[16]. Prenatal ultrasound findings were unremarkable. She was referred for genetic counseling, and repeat amniocentesis was performed at 21 weeks of gestation, which revealed a karyotype of 46,XX,dup(9)(q22.3q34.1)[7]/46,XX[25]. Simultaneous array comparative genomic hybridization (aCGH) on the DNA extracted from uncultured amniocytes revealed no genomic imbalance, or arr (1–22,X) × 2. Interphase fluorescence in situ hybridization (FISH) analysis on 105 uncultured amniocytes detected only one cell with the dup 9q signal with a mosaic dup 9q level of 1%, compared with 0% in normal control. At 37 weeks of gestation, a 2640-g female baby was delivered with no phenotypic abnormality. The cord blood had a karyotype of 46,XX,dup(9) (q22.3q34.1)[4]/46,XX[36], the umbilical cord had a karyotype of 46,XX,dup(9) (q22.3q34.1)[2]/46,XX[38], and the placenta had a karyotype of 46,XX. aCGH analysis on cord blood revealed no genomic imbalance. At age 2½ months, the baby was doing well, the peripheral blood of the baby had a karyotype of 46,XX,dup(9) (q22.3q34.1)[4]/46,XX[36], and interphase FISH analysis on buccal mucosal cells revealed no dup 9q signal in 100 buccal mucosal cells.ConclusionCytogenetic discrepancy may occur between cultured amniocytes and uncultured amniocytes in mosaic dup(9) (q22.3q34.1). Molecular cytogenetic analysis on uncultured amniocytes is useful for rapid distinguishing pseudomosaicism from true mosaicism under such a circumstance.     

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.     

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.     

Prenatal diagnosis and molecular cytogenetic characterization of mosaicism for a small supernumerary marker chromosome derived from chromosome 11

Objective

We present prenatal diagnosis and molecular cytogenetic characterization of a small supernumerary marker chromosome (sSMC) derived from chromosome 11.

Prenatal diagnosis and molecular cytogenetic characterization of mosaicism for a small supernumerary marker chromosome derived from chromosome 3

ObjectiveWe present prenatal diagnosis and molecular cytogenetic characterization of a small supernumerary marker chromosome (sSMC) derived from chromosome 3.Case reportA 36-year-old woman underwent amniocentesis at 19 weeks of gestation because of advanced maternal age. Amniocentesis revealed a karyotype of 47,XX,+mar[6]/46,XX[18]. The mother's karyotype was 47,XX,+mar[4]/46,XX[46]. The father's karyotype was 46.XY. Array comparative genomic hybridization (aCGH) analysis of uncultured amniocytes revealed a result of arr 3q11.1q12.1 (93,575,285–98,956,687) × 2–3 [GRCh37 (hg19)]. Prenatal ultrasound findings were unremarkable. The parents elected to continue the pregnancy, and a 2470-g female baby was delivered at 37 weeks of gestation without phenotypic abnormalities. The cord blood had a karyotype of 47,XX,+mar[8]/46,XX[32]. aCGH analysis of cord blood revealed a result of arr 3q11.1q11.2 (93,649,973–97,137,764) × 2.4 [GRCh37 (hg19)] with a log2 ratio of 0.25 and a 30–40% mosaicism for 3.488-Mb dosage increase in 3q11.1-q11.2 encompassing four [Online Mendelian Inheritance in Man (OMIM)] genes of PROS1, ARL13B, NSUN3 and EPHA6. Metaphase fluorescence in situ hybridization (FISH) analysis confirmed 30% (6/20 cells) mosaicism for the sSMC(3) in the blood lymphocytes.ConclusionaCGH and FISH analyses are useful for perinatal investigation of a prenatally detected sSMC.     

Prenatal diagnosis and molecular cytogenetic characterization of mosaicism for a small supernumerary marker chromosome derived from chromosome 2

Objective

We present prenatal diagnosis and molecular cytogenetic characterization of mosaicism for a small supernumerary marker chromosome (sSMC) derived from chromosome 2.

Detection of paternal uniparental disomy 9 in a neonate with prenatally detected mosaicism for a small supernumerary marker chromosome 9 and a supernumerary ring chromosome 9

Objective

We present the association of paternal uniparental disomy (UPD) 9 with mosaicism for a small supernumerary marker chromosome 9 [sSMC(9)] and a supernumerary ring chromosome 9 [r(9)].

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.     

Prenatal diagnosis and molecular cytogenetic characterization of a familial small supernumerary marker chromosome derived from the acrocentric chromosome 14/22

ObjectiveWe present prenatal diagnosis and molecular cytogenetic characterization of a familial small supernumerary marker chromosome (sSMC) derived from the acrocentric chromosome 14/22.Case reportA 40-year-old, gravida 2, para 1, woman underwent amniocentesis at 17 weeks of gestation because of advanced maternal age. Amniocentesis revealed a karyotype of 47,XY,+mar. Prenatal ultrasound was unremarkable. Simultaneous array comparative genomic hybridization (aCGH) analysis on the DNA extracted from uncultured amniocytes revealed no genomic imbalance. Cytogenetic analysis of the parental bloods revealed a karyotype of 47,XY,inv (9) (p12q13),+mar in the father and a karyotype of 46, XX in the mother. The sSMC was investigated by fluorescence in situ hybridization (FISH) analysis on cultured amniocytes using the CEP 13/21 α-satellite specific gene probe labeled with fluorescein isothiocyanate (FITC) fluorophore and the CEP 14/21 α-satellite specific gene probe labeled with Texas Red fluorophore (Cytocell Inc.). The result showed that the sSMC was derived from the chromosome 14/22, or+mar.ish dic (14/22) (D13Z1/D21Z1-, D14Z1/D22Z1+)[20]. A healthy male baby was delivered at term with no phenotypic abnormality. Quantitative fluorescent polymerase chain reaction (QF-PCR) analysis on parental bloods and the child's peripheral blood was used to exclude uniparental disomy (UPD) (14) and UPD(22).ConclusionFISH analysis is useful for the determination of an sSMC derived from an acrocentric chromosome under the circumstance of no genomic imbalance at amniocentesis. QF-PCR analysis is useful for excluding the possible associated UPD.     

Prenatal diagnosis and molecular cytogenetic characterization of a small supernumerary marker chromosome derived from inv dup(15)

ObjectiveWe present prenatal diagnosis and molecular cytogenetic characterization of an inverted duplication of proximal chromosome 15 [inv dup(15)] presenting as a small supernumerary marker chromosome (sSMC) at amniocentesis associated with concomitant microduplication of 8q22.1.Materials and methodsA 39-year-old woman underwent amniocentesis at 16 weeks of gestation because of advanced maternal age, and the result was 47, XY, +mar dn. The woman requested for repeat amniocentesis at 20 weeks of gestation. Array comparative genomic hybridization (aCGH), fluorescence in situ hybridization (FISH), quantitative fluorescent polymerase chain reaction (QF-PCR) and DNA methylation analysis were applied to determine the nature of the sSMC.Results: aCGH on the uncultured amniocytes revealed the result of arr 8q22.1 (93,918,763–96,618,539) × 3.0, arr 15q11.2q13.2 (22,765,628–30,658,876) × 4.0, arr 15q13.2q13.3 (30,653,877–32,509,926) × 3.0 [GRCh37 (hg19)]. Interphase FISH analysis using RP11-34H12 [15q13.2; Texas Red, 30,709,033–30,893,021 (hg19)] on 100 uncultured amniocytes showed that 38 cells had three signals, 45 cells had four signals and 27 cells had two signals. The parental bloods had normal aCGH results. The karyotype of cultured amniocytes was 47, XY, +inv dup(15) (pter→q13::q13→pter) which was confirmed by metaphase FISH analysis. No informative markers could be found in QF-PCR analysis. DNA methylation analysis on cord blood confirmed a maternal origin of the 15q11-q13 gene dosage increase with a result of 15q11.2 SNRPN DNA hypermethylation. Postnatal cytogenetic analysis on cord blood, umbilical cord and placenta showed the results consistent with the prenatal diagnosis.ConclusionMolecular cytogenetic techniques are useful for rapid diagnosis of an inv dup(15) chromosome presenting as an sSMC 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.     

Low-level mosaic trisomy 17 at amniocentesis in a pregnancy associated with a favorable fetal outcome and cytogenetic discrepancy between cultured and uncultured amniocytes

ObjectiveWe present low-level mosaic trisomy 17 at amniocentesis in a pregnancy associated with a favorable fetal outcome and cytogenetic discrepancy between cultured and uncultured amniocytes.Case reportA 32-year-old, primigravid woman underwent amniocentesis at 18 weeks of gestation because of an increased nuchal translucency thickness of 3 mm in the first trimester sonographic screening. Amniocentesis revealed a karyotype of 47,XX,+17 [2]/46,XX [20]. Among 22 colonies of cultured amniocytes, two colonies had a karyotype of 47,XX,+17, whereas the rest 20 colonies had a karyotype of 46,XX. Simultaneous array comparative genomic hybridization (aCGH) on the DNA extracted from uncultured amniocytes revealed arr (1–22,X) × 2 with 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) 17. The woman was encouraged to continue the pregnancy. A normal 3178-g female baby was delivered at 38 weeks of gestation without any phenotypic abnormalities. The karyotypes of cord blood, umbilical cord and placenta were all 46, XX (40/40 cells). When follow-up at age six months, the neonate was normal in physical and psychosomatic development.ConclusionLow-level mosaic trisomy 17 at amniocentesis can be a transient and benign condition, and can be associated with a favorable fetal outcome and cytogenetic discrepancy between cultured and uncultured amniocytes.     

Molecular cytogenetic characterization of mosaicism for a small supernumerary marker chromosome derived from chromosome 8 associated with congenital hypoplasia of the tongue and review of the literature

ObjectiveTo present molecular cytogenetic characterization of mosaic supernumerary ring chromosome 8 which has trisomy of a region of chromosome 8p12-q21.13 associated with congenital hypoplasia of the tongue and review of the literature.Case reportA 27 year-old woman presented with congenital hypoplasia of the tongue. The chromosome karyotype of peripheral blood lymphocytes was detected by conventional cytogenetic analysis. The genome copy number variations were detected by SNP array. Conventional cytogenetic analysis of the peripheral blood revealed a karyotype of 47,XX,+mar[60]/46,XX[40]. SNP array revealed that there was a duplication of 45.2 Mb at arr[hg19] 8p12q21.13(36,013,636–81,263,140) × 2–3.ConclusionWith this study a patient involving mosaic trisomy 8p12-q21.13 along with clinical properties, is described and compared to previously reported cases involving a small supernumerary marker chromosome (sSMC) derived from chromosome 8.     

Molecular cytogenetic characterization of a de novo small supernumerary marker chromosome derived from chromosome 15 in a pregnancy with incidental detection of a maternal Robertsonian translocation of 45,XX,der(13;14) (q10;q10)

ObjectiveWe present molecular cytogenetic characterization of a small supernumerary marker chromosome (sSMC) derived from chromosome 15 in a pregnancy with incidental detection of a maternal Robertsonian translocation of 45,XX,der(13; 14) (q10; q10).Case reportA 37-year-old, primigravid woman underwent amniocentesis at 16 weeks of gestation because of advanced maternal age. Amniocentesis revealed a karyotype of 47,XY,+mar. Simultaneous array comparative genomic hybridization (aCGH) analysis on the DNA extracted from uncultured amniocytes showed the result of no genomic imbalance or arr (1–22) × 2, (X,Y) × 1. Cytogenetic analysis of the parents showed a karyotype of 45,XX,der(13; 14) (q10; q10) in the mother and a karyotype of 46,XY in the father. Prenatal ultrasound was unremarkable. At 38 weeks of gestation, a 2790-g phenotypically normal male baby was delivered. The cord blood had a karyotype of 47,XY,+mar. Metaphase fluorescence in situ hybridization (FISH) analysis showed the result of +mar.ish dic(15) (D15Z1++, SNRPN-, PML-) (18/20). The extra chromosome was derived from chromosome 15.ConclusionMetaphase FISH analysis is useful for the identification of the origin of an sSMC in the presence of no genomic imbalance at aCGH analysis. Prenatal diagnosis of a de novo sSMC may be associated with a Robertsonian translocation in the parents, and parental cytogenetic analysis is necessary under such a circumstance.     

45,X/46,XX at amniocentesis associated with cytogenetic discrepancy between cultured amniocytes and uncultured amniocytes and in different amniocenteses and a favorable fetal outcome with a normal karyotype at birth

ObjectiveWe present 45,X/46,XX at amniocentesis associated with cytogenetic discrepancy between cultured amniocytes and uncultured amniocytes and in different amniocenteses and a favorable fetal outcome with a normal karyotype at birth.Case reportA 35-year-old, gravida 3, para 2, woman underwent amniocentesis at 20 weeks of gestation because of advanced maternal age. Amniocentesis revealed a karyotype of 45,X[11]/46,XX[108], consistent with 9.2% mosaicism for 45,X. Prenatal ultrasound findings were unremarkable. She was referred for genetic counseling at 25 weeks of gestation, and repeat amniocentesis at 26 weeks of gestation revealed a karyotype of 45,X[4]/46,XX[16], consistent with 20% mosaicism for 45,X. Simultaneous array comparative genomic hybridization (aCGH) analysis on the DNA extracted from uncultured amniocytes using SurePrint G3 Unrestricted CGH ISCA v2, 8 × 60K (Agilent Technologies, Santa Clara, CA, USA) revealed arr (1–22, X) × 2, Y × 0 with no genomic imbalance. The woman was advised to continue pregnancy, and at 38 weeks of gestation, a healthy 3140-g female baby was delivered with no phenotypic abnormalities. The cord blood had a karyotype of 46,XX (40/40 cells). When follow-up at age two months, the neonate had normal development and a normal karyotype.ConclusionConfirmation of 45,X/46,XX at amniocentesis should include conventional cytogenetic analysis and karyotyping on cultured amniocytes, and sole molecular analysis on uncultured amniocytes may miss the diagnosis of 45,X/46,XX.