Prenatal diagnosis and genetic analysis of a fetus with 47,XX,+21/46,XX mosaicism and XX/XY chimerism.

Prenatal diagnosis of simultaneous occurrence of chimerism and autosomal mosaicism is extremely rare. We report the prenatal diagnosis and genetic analysis of a fetus in a twin pregnancy with mosaic 47,XX,+21/46,XX with chimeric XX/XY. A 36-year-old, para 1, woman was referred for genetic counseling at 20 weeks' gestation because of abnormal karyotype (47,XX,+21/46,XX) in one fetus in a twin pregnancy. Cordocentesis revealed 47,XX,+21[3]/46,XX[35]/46,XY[7] in this fetus. Postnatal cytogenetic analysis of cord blood confirmed three cell lines in this twin (A) and 46,XY in the co-twin (B). Postmortem pathologic findings of both fetuses were normal. Fluorescence in situ hybridization identified three cell lines in the cord blood of twin A. Molecular genetic analysis using polymorphic DNA markers revealed parental origin of fetal tissue, and confirmed the chimeric status. Molecular genetic analysis with polymorphic DNA markers help to differentiate chimerism from mosaicism and define the origin of cell lines, which may have importance in genetic counseling.     

Fetal blood chromosome analysis: some new indications for prenatal karyotyping

Summary. Prenatal karyotyping using stimulated fetal blood lymphocytes was undertaken in 170 pregnancies between 16 and 36 weeks gestation for the following reasons-(1) mosaicism or marker chromo somes found in amniotic fluid culture; (2) a family history of X-linked mental retardation with fragile Xq28; (3) fetal abnormalities detected ultrasonographically; (4) late booking or amniotic fluid culture failure in patients with advanced age or balanced translocations; and ( 5 ) twin pregnancies discordant for a chromosomal anomaly. Forty-one karyotypic abnormalities were detected (24%). These were: 45,X (7 cases). trisomy 13 ( 5 cases), trisomy 18 (6 cases), trisomy 21 (4 cases), twin pregnancy where one twin had trisomy 21 (1 case), supernumerary marker chromosome (3 cases, one of which occurred in a twin pregnancy). triploidy (3 cases), X-linked mental retardation with fragile site at Xq28 in males (6 cases), fetal erythroleukaemia (3 cases including 2 cases with Turner's), Fanconi's anaemia (1 case), unbalanced chromosome translocation 47,XY+der22,t(l1;22) mat (1 case), mos 46,XXI8p-/46,XX.-18,+i(l8q) (1 case), 46,XXde1(2q) (1 case), and 46,XYt(5;17) de novo (1 case). In fetuses at high risk of a chromosome aberration. a rapidly obtaincd karyotype is helpful and fetoscopy and fetal blood sampling are justified in the second or third trimester.     

Fetal blood chromosome analysis: some new indications for prenatal karyotyping

Prenatal karyotyping using stimulated fetal blood lymphocytes was undertaken in 170 pregnancies between 16 and 36 weeks gestation for the following reasons--mosaicism or marker chromosomes found in amniotic fluid culture; a family history of X-linked mental retardation with fragile Xq28; fetal abnormalities detected ultrasonographically; late booking or amniotic fluid culture failure in patients with advanced age or balanced translocations; and twin pregnancies discordant for a chromosomal anomaly. Forty-one karyotypic abnormalities were detected (24%). These were: 45,X (7 cases), trisomy 13 (5 cases), trisomy 18 (6 cases), trisomy 21 (4 cases), twin pregnancy where one twin had trisomy 21 (1 case), supernumerary marker chromosome (3 cases, one of which occurred in a twin pregnancy), triploidy (3 cases), X-linked mental retardation with fragile site at Xq28 in males (6 cases), fetal erythroleukaemia (3 cases including 2 cases with Turner's), Fanconi's anaemia (1 case), unbalanced chromosome translocation 47,XY+der22,t(11;22) mat (1 case), mos 46,XX18p-/46,XX,-18+i(18q) (1 case), 46,XXdel(2q) (1 case), and 46,XYt(5;17) de novo (1 case). In fetuses at high risk of a chromosome aberration, a rapidly obtained karyotype is helpful and fetoscopy and fetal blood sampling are justified in the second or third trimester.     

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.     

Prenatal diagnosis and molecular cytogenetic characterization of mosaicism for a small supernumerary marker chromosome derived from ring chromosome 4

ObjectiveTo present prenatal diagnosis and molecular cytogenetic characterization of mosaicism for a small supernumerary marker chromosome (sSMC) derived from ring chromosome, or r(4) by spectral karyotyping (SKY), fluorescence in situ hybridization (FISH), and array comparative genomic hybridization (aCGH).Materials, Methods, and ResultsA 37-year-old, primigravid woman underwent amniocentesis at 18 weeks of gestation because of advanced maternal age. Amniocentesis revealed a de novo ring-shaped sSMC in 16 of 31 amniocyte colonies. The parental karyotypes were normal. Level II ultrasound findings were unremarkable. Repeated amniocentesis revealed a karyotype of 47,XX,+mar[17]/46,XX[19]. The sSMC was characterized by SKY and FISH, which showed a chromosome 4 origin of the sSMC. aCGH demonstrated a 21.7-Mb gain in the gene dosage encompassing the region of 4p12→q13.2. The sSMC was r(4)(p12q13.2). The fetal karyotype was 47,XX,+r(4)(p12q13.2)[17]/46,XX[19]. The pregnancy was subsequently terminated. The fetus postnatally manifested hypertelorism, epicanthic folds, a prominent nose, a triangular face, low-set ears, clinodactyly of the fingers, and small big toes. Postnatal cytogenetic analyses of fetal and extraembryonic tissues revealed the karyotypes of 47,XX,+r(4)[18]/46,XX[21] in cord blood, 47,XX,+r(4)[20]/48,XX,+r(4),+r(4)[1]/46,XX[9] in umbilical cord, 47,XX,+r(4)[14]/47,XX,+dic r(4)[1]/46,XX[25] in skin, 47,XX,+r(4)[15]/46,XX[25] in amnion, and 47,XX,+r(4)[12]/47,XX,+dic r(4)[1]/46,XX[2] in placenta.ConclusionSKY, FISH, and aCGH are helpful in genetic counseling of prenatally detected sSMCs by providing the immediate and thorough information on the origin and genetic component of the sSMC.     

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.     

Uncommon chromosomal mosaicism in chorionic villi.

Three cases of unusual chromosomal mosaicism are reported for which the cytogenetic data show inconsistent findings between CVS and AC or fetal tissue, and which cannot be explained simply by non-disjunction. For case 1, in CVS the karyotype was 46,XY, whereas lymphocytes and fibroblasts revealed 69,XXY. DNA fingerprinting indicated one paternal and two maternal chromosome sets, the latter most probably due to omission of maternal meiosis II. For case 2, in CVS mos 46,XX/47,XX,+ mar de novo was observed. Amniotic fluid cells had the karyotype 46,XX. The origin of the marker chromosome might be explained by at least two events of unknown order (a somatic chromosome/chromatid deletion and non-disjunction of the homologous chromosome). In case 3 (CVS: mos 46,XY/46,XY,19q+ de novo; amniotic fluid cells, lymphocytes, and fibroblasts: 46,XY), the surplus of chromosome material in 19q+ might be explained on the basis of a somatic translocation. The idea of a chimera is less convincing, as the mosaic finding is restricted to one tissue. Furthermore, there was no hint of a vanishing twin. Hitherto, no case of structural chromosome mosaicism in CVS has been reconfirmed in fetal tissues.     

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.     

Complete discrepancy between QF-PCR analysis of uncultured villi and karyotyping of cultured cells in the prenatal diagnosis of trisomy 21 in three CVS

OBJECTIVE: To investigate complete discrepancies in the prenatal diagnosis of trisomy 21 between QF-PCR analysis of uncultured villi and karyotyping of cultured cells in three chorion villus samples. METHODS: Clinical details were obtained from all three patients. Follow-up studies were undertaken where possible by evaluation of chromosome 21 copy number with QF-PCR, interphase FISH, MLPA and karyotyping, and by post-mortem examination. RESULTS: Case 1: severe oligohydramnios and microcephaly on scan. QF-PCR: trisomy 21; MLPA: trisomy 21; cultured karyotype: 46,XY[48]. Placental and fetal tissue results and post-mortem examination indicated a euploid fetus with trisomy 21 mosaicism confined to the placenta. Case 2: Down screen risk 1:16; NT = 4.4 mm; absent nasal bone (Caucasian mother). QF-PCR: disomy 21; cultured karyotype: 47,XY,+ 21[23]. Neck thickening noted at delivery-post-mortem refused, no fetal tissue available. Placental tissue indicated mosaicism for trisomy 21. Case 3: Down screen risk 1:91; NT = 6.7 mm. QF-PCR: disomy 21; cultured karyotype: 46,XX,der(21;21)(q10;q10)[60]. No follow-up possible. PCR genotyping of cultured cells confirmed sample identity in all three cases. Chromosome 21 markers observed by PCR were biallelic in all three cases, indicating that a mitotic error could account for the presence of the abnormal cell lines in each case. CONCLUSION: QF-PCR analysis of uncultured villi and cultured karyotyping may rarely show complete discrepancy in the prediction of fetal trisomy 21 in CVS. Within-biopsy sample mosaicism, together with the testing of different cell populations, provide an explanation for these results. Practical ways to minimise the risk of such discrepancy are proposed.     

Mosaic tetrasomy 9p at amniocentesis in a pregnancy associated with a favorable fetal outcome,perinatal progressive decrease of the aneuploid cell line and cytogenetic discrepancy in various tissues

ObjectiveWe present mosaic tetrasomy 9p at amniocentesis in a pregnancy associated with a favorable fetal outcome, perinatal progressive decrease of the aneuploid cell line and cytogenetic discrepancy in various tissue.Case reportA 33-year-old primigravid woman underwent elective amniocentesis at 18 weeks of gestation because of anxiety, and the karyotype of cultured amniocytes was 47,XX,+i (9) (p10)[20]/46,XX [55]. Cordocentesis was performed at 20 weeks of gestation, and the karyotype of cord blood was 47,XX,+i (9) (p10)[7]/46,XX [15]. She was referred for genetic counseling at 23 weeks of gestation, and repeat amniocentesis revealed a karyotype of 47,XX,+i (9) (p10)[1]/46,XX [16] with seven cells in one colony having tetrasomy 9p in cultured amniocytes, and in uncultured amniocytes, quantitative fluorescence polymerase chain reaction (QF-PCR) analysis excluded uniparental disomy (UPD) 9 and determined paternal origin of the extra i (9p), array comparative genomic hybridization (aCGH) analysis on the DNA extracted from uncultured amniocytes revealed arr 9p24.3p13.1 × 3.0 consistent with 50% mosaicism for tetrasomy 9p, and interphase fluorescence in situ hybridization (FISH) on uncultured amniocytes showed 22.6% (12/53 cells) mosaicism for tetrasomy 9p. A third amniocentesis at 27 weeks of gestation revealed a karyotype of 46, XX (10/10 colonies) in cultured amniocytes, and interphase FISH analysis on uncultured amniocytes revealed 20% (20/100 cells) mosaicism for tetrasomy 9p. The parental karyotypes and prenatal ultrasound were normal. At 39 weeks of gestation, a phenotypically normal 3388-g female baby was delivered. The karyotypes of cord blood, umbilical cord and placenta were 47,XX,+idic (9) (q12)[19]/46,XX [21] or 47,XX,+idic (9) (pter→q12:q12→pter)[19]/46,XX [21], 47,XX,+idic (9) (q12)[1]/46,XX [39] and 47,XX,+idic (9) (q12)[4]/46,XX [36], respectively. When follow-up at age two months, the neonate was phenotypically normal, the peripheral blood had a karyotype of 47,XX,+idic (9) (q12)[18]/46,XX [22], and interphase FISH analysis on 100 buccal mucosal cells revealed 1% (1/100 cells) mosaicism for tetrasomy 9p. When follow-up at age seven months, the neonate was phenotypically normal, and the peripheral blood had a karyotype of 47,XX,+idic(9)(q12)[14]/46,XX[26].ConclusionMosaic tetrasomy 9p at amniocentesis can be a transient and benign condition, and can be associated with a favorable fetal outcome and perinatal progressive decrease of the aneuploid cell line and cytogenetic discrepancy in various tissue.     

Perinatal cytogenetic discrepancy in a fetus with low-level mosaicism for trisomy 21 and a favorable outcome

ObjectiveWe present perinatal cytogenetic discrepancy in a fetus with low-level mosaicism for trisomy 21 and a favorable outcome.Case reportA 40-year-old woman underwent amniocentesis at 19 weeks of gestation because of advanced maternal age. Amniocentesis revealed a karyotype of 47,XY,+21[7]/46,XY[14]. She underwent cordocentesis 21 weeks of gestation, and the karyotype of cord blood was 47,XY,+21[13]/46,XY[38]. The prenatal ultrasound findings were unremarkable. After genetic counseling of a favorable outcome of low-level mosaic trisomy 21 at amniocentesis, the parents decided to continue the pregnancy, and a 3128-g phenotypically normal male baby was delivered at 38 weeks of gestation without phenotypic features of Down syndrome. Postnatal cytogenetic analysis of cord blood revealed a karyotype of 47,XY,+21[3]/46,XY[47]. The placenta had a karyotype of 47,XY,+21[8]/46,XY[32], and the umbilical cord had a karyotype of 47,XY,+21[5]/46,XY[35]. Array comparative genomic hybridization analysis on the DNA extracted from cord blood revealed no genomic imbalance. Polymorphic DNA marker analysis excluded uniparental disomy 21. Interphase fluorescence in situ hybridization analysis on urinary cells revealed trisomy 21 signals in 2/102 (1.96%) cells compared with 2/103 (1.94%) cells in normal control.ConclusionThe cells of abnormal cell line in prenatally detected mosaic trisomy 21 may decrease in number or disappear in various tissues as the fetus grows, and there exists perinatal cytogenetic discrepancy in mosaic trisomy 21 detected at prenatal diagnosis.     

Clinical, cytogenetic, and molecular findings of prenatally diagnosed mosaic trisomy 4

OBJECTIVES: To present the clinical, cytogenetic, and molecular findings of prenatally diagnosed mosaic trisomy 4. CASE: An amniocentesis was performed at 21 weeks' gestation because of maternal anxiety. Cytogenetic analysis revealed mosaicism for trisomy 4, 47,XX,+4[4]/46,XX[16]. Level II ultrasound demonstrated tetralogy of Fallot. Repeated amniocentesis at 23 weeks' gestation revealed 47,XX,+4[4]/46,XX[19]. The pregnancy was terminated. Phenotypic findings included tetralogy of Fallot, hypertelorism, micrognathia, abnormal ears, duplicated phalanges of the left thumb, clinodactyly, and overlapping of the toes. The karyotype of the cord blood was 46,XX. Cytogenetic analyses of the multiple tissue samplings showed a karyotype of 47,XX,+4 in 40/40 cells of the amniotic membrane (amnion), and 47,XX,+4/46,XX with various levels of trisomy 4 in the cells of the liver, lungs, placenta, skin, and umbilical cord. The levels of trisomy 4 were 11/40 in the liver, 8/40 in the lungs, 31/40 in the placenta, 9/40 in the skin, and 8/40 in the umbilical cord. METHOD: The parental origin and meiotic origin of trisomy 4 were determined by examining the amniotic membrane using quantitative fluorescent polymerase chain reaction assays with polymorphic markers specific for chromosome 4. The result was consistent with a paternal meiosis I nondisjunction error. The cord blood showed a biparental inheritance. An extra paternal heterozygous allele with partial dosage increase was noted in other fetal and extraembryonic tissues studied. CONCLUSION: A diagnosis of trisomy 4 mosaicism in amniocytes indicates an increased risk for fetal abnormalities. Associated abnormal findings include congenital heart defects and anomalies of the digits and thumb. A confirmatory placental sampling may be helpful, whereas a fetal blood sampling is of a very limited value. A postnatal amnion sampling may provide additional clues to the fetal involvement of trisomy 4.     

Parental mosaic trisomy 21 detected following maternal cell contamination of an amniotic fluid specimen from a normal male pregnancy

We report a case of maternal mosaic trisomy 21 ascertained at prenatal diagnosis as a result of maternal cell contamination of an amniotic fluid sample. A 34 year old female was referred for karyotyping because of a previous trisomy 21 pregnancy. Chromosome analysis of primary in situ cultures showed a karyotype of 47,XX, + 21[6]/46,XY[32]/46,XX[2]. Molecular testing demonstrated maternal cell contamination of the amniotic fluid sample and G-banded karyotyping of maternal blood showed that 3/200 cells had trisomy 21, consistent with the mother being a Down syndrome mosaic. A normal male baby with a 46,XY chromosome complement was delivered at 30 weeks. This case emphasises the need for close collaboration between cytogenetic and molecular genetics laboratories in resolving unusual cases of mosaicism.     

Examination of fetal cells and cell-free fetal DNA in maternal blood for fetal gender determination

BACKGROUND: To assess applicability of noninvasive methods for prenatal sex determination, both intact fetal cells and cell-free DNA from maternal blood were studied. METHODS: Maternal peripheral blood samples were obtained from 41 women carrying chromosomally normal fetuses and from 3 women with aneuploid fetuses (47,XX,+18; 47,XY,+18 and 47,XY,+21) at 9-22 weeks of gestation. DNA was extracted from the plasma fraction and analyzed by the nested polymerase chain reaction (PCR) using Y chromosome specific primers. After fetal cells were enriched by MACS, fluorescence in situ hybridization (FISH) with chromosome X and Y specific probes was performed to detect XY cells. RESULTS: Although Y-chromosome-specific DNA was detected by PCR analysis in all maternal plasma samples with male fetuses, 26% women bearing female fetuses also gave positive results. By FISH analysis, XY cells were detected in not only 58% of women bearing male fetuses, but also 13% of their counterpoints with female fetuses. CONCLUSIONS: Our findings suggested that consistent results for fetal gender using PCR or FISH cannot be obtained with intact fetal cells and cell-free DNA present in maternal blood and plasma at 9-22 weeks of gestation, despite their apparent abundant presence.     

Fetal chromosomal analysis of pregnancies following intracytoplasmic sperm injection with amniotic tissue culture

OBJECTIVES: The objective of this study was to determine the incidence of chromosomal anomalies in a complete cohort of ICSI pregnancies. METHODS: From January 1996 to December 2000, 1500 consecutive patients who had become pregnant after Intracytoplasmic Sperm Injection (ICSI) were given prenatal genetic counseling and 98 of them (6.5%) who accepted amniocentesis were studied. Amniocentesis was performed between 14 and 20th weeks of their pregnancy. Amniotic tissue cultures were processed according to Hoehn et al. A minimum of 20 metaphases were examined on each preparation. Both parents were also evaluated with peripheral blood karyotyping. RESULTS: Amniocentesis and karyotyping was performed to evaluate the 142 fetuses from 98 ICSI pregnancies. Karyotypes from peripheral leucocytes of the parents were also evaluated. Chromosomal anomalies were detected from 6 out of the 142 (4.2%) fetuses. The anomalies were as follows, '46,XX/69,XXX/92,XXXX', '46,XY/69,XXY/92,XXYY', '47,XY + 21', '46,XY/47,XY + 7', '47,XXY', and '45,X0'. All except one pregnancy were terminated with the consent of the couples. Fetal tissue cultures were also studied after the termination of the pregnancy in order to confirm prenatal diagnosis. We did not detect abnormal karyotype from the parents of these fetuses. CONCLUSIONS: The ratio of chromosomal abnormalities seems to be slightly increased in ICSI pregnancies. Paternal factors due to morphologically abnormal spermatozoa, maternal factors due to increased mother age and more frequently, de novo occurring sex chromosomal abnormalities may be responsible for this outcome.     

Prenatally detected trisomy 4 and 6 mosaicism--cytogenetic results and clinical phenotype

We report on a live-born male with 46,XY/47,XY+4/47,XY,+6 mosaicism. Trisomy 4 mosaicism was detected by karyotyping chorionic villus samples (CVS) and was confirmed by the analysis of 16 metaphases obtained from cultured amniotic fluid cells. Eight metaphases were normal (46,XY), two had trisomy 4 (47,XY,+4), and two had trisomy 6 (47,XY,+6). Two postnatal chromosomal analyses of blood lymphocytes at birth and at the age of one week were normal. Chromosomal analysis of cultured skin fibroblasts from the right inguinal region at the age of 12 months revealed trisomy 4 (47,XY,+4) in 49 metaphases, trisomy 6 (47,XY,+6) in 2 metaphases, and a normal karyotype (46,XY) in 49 cells of the 100 analyzed metaphases, respectively. The main clinical findings consist of prenatal growth retardation, hypoplasia of the right side of the face, a dysplastic and posteriorly rotated right ear, a high vaulted palate, retrognathia, aplasia of the right thumb, hypoplasia of the fingernails, a deep sacral dimple, and patchy skin hypopigmentation of the right leg. When last seen at the age of 14 months, his development was nearly normal. Five patients with trisomy 4 mosaicism have been reported previously, but none with an additional trisomy 6 mosaicism.     

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.     

Prenatal diagnosis of trisomy 11 in a single colony of cultured amniocytes at amniocentesis in a pregnancy with a favorable outcome

ObjectiveWe present prenatal diagnosis of trisomy 11 in a single colony of cultured amniocytes at amniocentesis and the perinatal outcome.Case reportA 36-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,XX,+11[1]/46,XX[16]. In 17 colonies of cultured amniocytes, all five cells in one colony had a karyotype of 47,XX,+11, while the rest 16 colonies had a normal karyotype. The parental karyotypes were normal. Repeat amniocentesis was performed at 21 weeks of gestation. Interphase fluorescence in situ hybridization (FISH) was applied on the uncultured amniocytes, and the result revealed 0.9% mosaicism (1/101 cells) for trisomy 11 with only one cell with three signals, while the other 100 cells had two signals, compared with no trisomy 11 signals (0/100 cells) in the normal control. Uniparental disomy (UPD) 11 was excluded by polymorphic DNA marker analysis on the DNAs extracted from uncultured amniocytes and parental bloods. The cultured amniocytes at repeat amniocentesis revealed a karyotype of 46, XX in 28/28 colonies. Prenatal ultrasound findings were unremarkable. The pregnancy was continued to 38 weeks of gestation, and a 2724-g healthy female baby was delivered. The cord blood had a karyotype of 46,XX. The interphase FISH analysis on buccal mucosal cells revealed no trisomy 11 signals (0/100 cells). When follow-up at three months of age, the neonate manifested normal psychomotor and physical development.ConclusionPrenatal diagnosis of mosaic trisomy 11 in a single colony at amniocentesis without abnormal fetal ultrasound and UPD 11 can be associated with a favorable outcome.     

Prenatal diagnosis of mosaic trisomy 8: clinical report and literature review

ObjectiveTo present prenatal diagnosis of mosaic trisomy 8 and to review the literature.Materials, Methods, and ResultsA 34-year-old woman underwent amniocentesis at 16 weeks of gestation because of advanced maternal age. Amniocentesis revealed a karyotype of 47,XY,+8[6]/46,XY[31]. Repeated amniocentesis at 21 weeks of gestation revealed a karyotype of 47,XY,+8[4]/46,XY[77]. Interphase fluorescence in situ hybridization analysis of uncultured amniocytes showed 25% (5/20) mosaicism for trisomy 8. Array comparative genomic hybridization (aCGH) and quantitative fluorescent polymerase chain reaction (QF-PCR) analyses of uncultured amniocytes revealed no genomic imbalance in chromosome 8. The result of QF-PCR excluded uniparental disomy 8. At 23 weeks of gestation, the woman underwent amniocentesis and cordocentesis at other hospitals. Amniocentesis revealed a karyotype of 47,XY,+8[6]/46,XY[10]. Cordocentesis revealed a karyotype of 47,XY,+8[1]/46,XY[29]. Level II ultrasound findings were unremarkable. The parents decided to continue the pregnancy. A 1373-g male baby was prematurely delivered at 29 weeks of gestation. The peripheral blood had a karyotype of 47,XY,+8[1]/46,XY[29]. The infant had normal growth and mental development at 4 months of age.ConclusionFetuses with mosaic trisomy 8 are compatible with viability and can have a favorable outcome. QF-PCR and array comparative genomic hybridization have the limitation of detection of low-level mosaicism. We suggest that in instances of repeated amniocentesis for confirmation of mosaic trisomy 8, follow-up investigations should include interphase fluorescence in situ hybridization studies on uncultured amniocytes, uniparental disomy tests, and detailed ultrasound examinations.     

Prenatal diagnosis of mosaicism for trisomy 12 in a single colony at amniocentesis in a pregnancy with a favorable outcome

ObjectiveWe present prenatal diagnosis of mosaicism for trisomy 12 in a single colony at amniocentesis with a favorable outcome.Case reportA 36-year-old woman underwent amniocentesis at 18 weeks of gestation because of advanced maternal age. Amniocentesis revealed a karyotype of 47,XY,+12[1]/46,XY[14]. In 15 colonies of cultured amniocytes, all three cells in one colony had the karyotype of 47,XY,+12, while the rest 14 colonies had the karyotype of 46,XY. The parental karyotypes were normal. Prenatal ultrasound findings were unremarkable. Polymorphic DNA marker analysis using the DNAs extracted from cultured amniocytes and parental bloods excluded uniparental disomy (UPD) 12. At 37 weeks of gestation, a healthy 2,828-g male baby was delivered with no phenotypic abnormality. The cord blood had a karyotype of 46,XY in 40/40 lymphocytes. Postnatal interphase fluorescence in situ hybridization (FISH) analysis on buccal cells and urinary cells revealed normal signals in 72/72 buccal cells, and trisomy 12 signals in 1/47 (2.1%) urinary cells compared with 0% (0/75 cells) of trisomy 12 signals in the normal control.ConclusionMosaicism for trisomy 12 in a single colony at amniocentesis without UPD 12 and fetal ultrasound abnormalities can be associated with a favorable outcome.