Prenatal diagnosis and molecular cytogenetic characterization of de novo partial monosomy 3p (3p26.3→pter) and partial trisomy 16q (16q23.1→qter)

AbstractObjectiveTo present the prenatal diagnosis and molecular cytogenetic characterization of a de novo unbalanced reciprocal translocation.Case ReportA 37-year-old woman, G3P1, underwent amniocentesis at 17 weeks of gestation because of her advanced maternal age. Her husband was 38 years old. Amniocentesis revealed a derivative chromosome 3 with the deletion of terminal 3p and the addendum of an unknown extra chromosomal segment on the distal 3p. The parental karyotypes were normal. Prenatal ultrasound findings were unremarkable. Array comparative genomic hybridization (aCGH) analysis using cultured amniocytes revealed a 2.38-Mb deletion in 3p26.3 [arr 3p26.3 (1-2,380,760)×1] encompassing 15 genes, which included 3 OMIM genes CHL1, CNTN6, and CNTN4, and a 13.17-Mb duplication in 16q23.1-q24.3 [arr 16q23.1q24.3 (76,999,082-90,170,596)×3] encompassing 207 genes, which included 81 OMIM genes. The pregnancy was subsequently terminated, and a malformed fetus was delivered with facial dysmorphism. Postnatal cord blood analysis revealed a karyotype of 46,XY,der(3)t(3;16)(p26.3;q23.1)dn. Polymorphic DNA marker analysis by quantitative fluorescent polymerase chain reaction (QF-PCR) on the DNAs extracted from the placenta and parental blood showed a paternal origin of the aberrant chromosome.ConclusionThe aCGH and QF-PCR analyses helped in delineating the genomic imbalance and parental origin of prenatally detected de novo unbalanced reciprocal translocation

De novo duplication of Xq22.1→q24 with a disruption of the NXF gene cluster in a mentally retarded woman with short stature and premature ovarian failure

AbstractObjectiveTo present molecular cytogenetic characterization of a de novo duplication of Xq22.1→q24 in a mentally retarded woman with short stature and premature ovarian failure.Materials and MethodsA 19-year-old woman presented with psychomotor retardation, developmental delay, mental retardation, short stature, low body weight, general muscle hypotonia, distal muscle hypotrophy of the lower extremities, elongated digits, scanty pubic and axillary hair, hypoplastic external female genitalia, and secondary amenorrhea but no clinical features of Pelizaeus-Merzbacher disease. Conventional cytogenetic analysis revealed a karyotype of 46,X,dup(X)(q22.1q24). Fluorescence in situ hybridization determined a direct duplication with a linear tandem orientation. Array comparative genomic hybridization demonstrated partial trisomy Xq [arr cgh Xq22.1q24 (101,490,234–119,070,188 bp)×3] with a 17.6-Mb duplication.ResultsThe duplicated region contained NXF2B, NXF4, NXF3, PLP1, and PGRMC1 genes. There was a disruption of the NXF gene cluster of Xcen-NXF5-NXF2-NXF2B-NXF4-NXF3-Xqter.ConclusionA duplication of Xq22.1→q24 with a disruption of the NXF gene cluster in female patients can be associated with clinical manifestations of mental retardation in addition to short stature and premature ovarian failure

Prenatal Diagnosis and Molecular Cytogenetic Characterization of a Small Supernumerary Marker Chromosome Derived from Chromosome 18 and Associated With a Reciprocal Translocation Involving Chromosomes 17 And 18

SummaryObjectivePrenatal diagnosis of small supernumerary marker chromosomes (sSMC) gives rise to difficulties in genetic counseling, and requires molecular cytogenetic technologies such as spectral karyotyping, fluorescence in situ hybridization, multicolor-fluorescence in situ hybridization, or array-comparative genomic hybridization to identify the nature of the aberrant chromosome. We report such a case associated with a reciprocal translocation.Materials, Methods and ResultsA 36-year-old woman, gravida 7, para 1, abortus 5, was referred for amniocentesis at 18 weeks of gestation because of advanced maternal age. Amniocentesis revealed a reciprocal translocation between chromosomes 17q and 18q and an sSMC. The karyotype was 47,XY,t(17;18)(q11.1;q11.2), +mar. Chromosome preparations from blood lymphocytes revealed that she had the same reciprocal translocation and sSMC. Spectral karyotyping showed that the sSMC was derived from the centromeric region of chromosome 18, and there was a reciprocal translocation between chromosomes 17 and 18. The derivative chromosome 17 had positive 17p terminal (17pTEL) and chromosome 17 centromeric (cep17) signals but did not have a positive chromosome 18 centromeric signal (cep18). The derivative chromosome 18 had positive 18p terminal (18pTEL), chromosome 18 centromeric (cep18) and cep17 signals. The sSMC had only a positive cep18 signal. These findings suggested that a breakpoint occurred at 17q11.1 and another at 18q11.2 during translocation, and the sSMC originated from chromosome 18. The karyotype of the fetus was thus 47,XY,t(17;18)(q11.1;q11.2), +mar.ish der(17)t(17;18)(q11.1;q11.2)(17pTEL+,D17Z1+),der(18)t(17;18)(q11.1;q11.2)(18pTEL+,D18Z1+,D17Z1+), + der(18)(D18Z1+). Oligonucleotide-based array comparative genomic hybridization demonstrated no gain or loss of the gene dosage on chromosomes 17 and 18.ConclusionOur case adds to the reported cases of sSMCs derived from the centromeric region of chromosome 18 without phenotypic consequences

Low-level mosaic trisomy 2 at amniocentesis in a pregnancy associated with positive NIPT and CVS results for trisomy 2, maternal uniparental disomy 2, perinatal progressive decrease of the aneuploid cell line, cytogenetic discrepancy between cultured amniocytes and uncultured amniocytes, intrauterine growth restriction and a favorable fetal outcome

Objective: We present low-level mosaic trisomy 2 at amniocentesis in a pregnancy associated with positive non-invasive prenatal testing (NIPT) and chorionic villus sampling (CVS) results for trisomy 2, maternal uniparental disomy (UPD) 2, perinatal progressive decrease of the aneuploid cell line, cytogenetic discrepancy between cultured amniocytes and uncultured amniocytes, intrauterine growth restriction (IUGR) and a favorable fetal outcome. Case Report: A 35-year-old, primigravid woman underwent amniocentesis at 16 weeks of gestation because both NIPT at 9 weeks of gestation and CVS at 11 weeks of gestation revealed trisomy 2. This pregnancy was conceived by in vitro fertilization (IVF) and embryo transfer (ET). Amniocentesis revealed a karyotype of 47,XY,+2[11]/46,XY[19]. Prenatal ultrasound findings were normal. She was referred to the hospital for genetic counseling at 20 weeks of gestation, and repeat amniocentesis performed at 24 weeks of gestation revealed a karyotype of 46,XY (22/22 colonies). The parental karyotypes were normal. Quantitative fluorescent polymerase chain reaction (QF-PCR) analysis on the DNA extracted from uncultured amniocytes and parental bloods revealed maternal uniparental heterodisomy of chromosome 2. Simultaneous molecular cytogenetic analysis on uncultured amniocytes showed the results of arr 2p25.3q37.3 × 2.4 with a log2 ratio = 0.26, consistent with 40% mosaicism for trisomy 2 by array comparative genomic hybridization (aCGH), and 28% (28/100 cells) mosaicism for trisomy 2 by interphase fluorescence in situ hybridization (FISH). Despite IUGR on fetal ultrasound, the woman was advised to continue the pregnancy, and a 2252-g phenotypically normal male baby was delivered at 38 weeks of gestation. The karyotypes of cord blood, umbilical cord and placenta were 46,XY (40/40 colonies), 46,XY (40/40 colonies) and 47,XY,+2[9]/46,XY[31], respectively. QF-PCR analysis on cord blood, umbilical cord and placenta confirmed uniparental heterodisomy of chromosome 2 in the cord blood and umbilical cord, and maternal origin of trisomy 2 in the placenta. FISH analysis on buccal mucosal cells at age 1.5 months revealed 8.7% (9/104 cells) mosaicism for trisomy 2. When follow-up at age four months, the neonate manifested a normal phenotype except intermittent hypoventilation. Molecular analysis of the PHOX2B gene revealed a normal result. When follow-up at age one year, he manifested normal development. Conclusion: Mosaic trisomy 2 at prenatal diagnosis should alert the possibility of UPD 2 and include a UPD 2 testing. Low-level mosaic trisomy 2 at amniocentesis can be associated with perinatal progressive decrease of the aneuploid cell line and a favorable fetal outcome

Mosaicism for Robertsonian jumping translocation at amniocentesis: 45,XY,der(15;22)(q10;q10)mat/46,XY,i(15)(q10)/46,XY, genetic counseling, prenatal diagnosis and postnatal follow-up in a pregnancy with a favorable fetal outcome

Objective: We present genetic counseling, prenatal diagnosis and postnatal follow-up of 45,XY,der(15;22)(q10;q10)mat/46,XY,i(15)(q10)/46,XY at amniocentesis in a pregnancy with a favorable fetal outcome. Case report: A 27-year-old, primigravid woman underwent amniocentesis at 19 weeks of gestation because increased nuchal translucency thickness, and the result was 45,XY,der(15;22)(q10;q10)[29]/46,XY,i(15)(q10)[3]/46,XY[5]. Simultaneous array comparative genomic hybridization (aCGH) analysis on the DNA extracted from uncultured amniocytes revealed arr (1–22) × 2, (X,Y) × 1. The maternal karyotype was 45,XX,der(15;22)(q10;q10), and the paternal karyotype was 46,XY. She was referred for genetic counseling, and repeat amniocentesis performed at 23 weeks of gestation revealed 45,XY,der(15;22)(q10;q10)mat[23]/45,XY,-22[2]. aCGH analysis on uncultured amniocytes detected no genomic imbalance, and polymorphic DNA marker analysis excluded uniparental disomy (UPD) 15. Fluorescence in situ hybridization (FISH) analysis using the chromosome 15q specific probe and the chromosome 22q specific probe detected three 15q signals in 4/104 cells (3.8%). The woman was advised to continue the pregnancy, and, a 3186-g phenotypically normal male baby was delivered at 38 weeks of gestation. The umbilical cord had a karyotype of 45,XY,der(15;22)(q10;q10) (40/40 cells). When follow-up at age seven months, the neonate was normal in development, the peripheral blood had a karyotype of 45,XY,der(15;22)(q10;q10) (40/40 cells), and the buccal mucosal cells had normal signals in all 100 cells. Conclusions: Mosaicism for Robertsonian jumping translocations at amniocentesis can be a transient condition and can be associated with a familial Robertsonian translocation and a favorable fetal outcome. Prenatal diagnosis of a Robertsonian jumping translocation involving chromosome 15 should include UPD 15 testing to exclude UPD 15

Prenatal diagnosis of mosaic trisomy 18 and maternal uniparental disomy 18 by amniocentesis in a pregnancy associated with cytogenetic discrepancy in various tissues and a favorable fetal outcome

Objective: We present prenatal diagnosis of mosaic trisomy 18 and maternal uniparental disomy (UPD) 18 in a pregnancy with a favorable fetal outcome. Case report: A 34-year-old woman underwent amniocentesis at 17 weeks of gestation because of advanced maternal age, and the result was 47,XY,+18 [4]/46,XY [25] in cultured amniocytes. Simultaneous array comparative genomic hybridization (aCGH) on uncultured amniocytes revealed 65% mosaicism for trisomy 18. Prenatal ultrasound was normal. She consulted our hospital and underwent repeat amniocentesis at 22 weeks of gestation, and the result revealed a karyotype of 47,XY,+18 [9]/46,XY [12] in cultured amniocytes. Simultaneous aCGH on uncultured amniocytes revealed arr 18p11.32q23 × 2.4 (log2 ratio = 0.3) consistent with 40% mosaicism for trisomy 18. Parental karyotypes were normal. Quantitative fluorescent polymerase chain reaction (QF-PCR) analysis on the DNA extracted from parental bloods and uncultured amniocytes confirmed maternal uniparental heterodisomy of chromosome 18. At 26 weeks of gestation, she underwent the third amniocentesis which revealed a karyotype of 47,XY,+18 [7]/46,XY [19] in cultured amniocytes. Simultaneous aCGH on uncultured amniocytes revealed arr 18p11.32q23 × 2.4 (log2 ratio = 0.27) consistent with 40% mosaicism for trisomy 18. Interphase fluorescence in situ hybridization (FISH) on uncultured amniocytes revealed 38% (38/100 cells) mosaicism for trisomy 18. The woman was advised to continue the pregnancy, and a 2620-g phenotypically normal male baby was delivered at 40 weeks of gestation. At birth, the karyotypes of cord blood, umbilical cord and placenta were 47,XY,+18 [14]/46,XY [26], 47,XY,+18 [9]/46,XY [31] and 47,XY,+18 (40/40 cells), respectively. When follow-up at age 2½ months, the neonate was phenotypically normal. The peripheral blood had a karyotype of 47,XY,+18 [28]/46,XY [12], and interphase FISH analysis on buccal mucosal cells detected 6.4% (7/93 cells) mosaicism for trisomy 18, compared with 0% (0/100 cells) in the normal control. When follow-up at age seven months, the neonate was normal in development, and the peripheral blood had a karyotype of 47,XY,+18 [18]/46,XY [22]. Conclusions: Mosaic trisomy 18 at amniocentesis can be associated with cytogenetic discrepancy in various tissues, UPD 18 and a favorable fetal outcome. Prenatal diagnosis of mosaic trisomy 18 should alert the possibility of UPD 18 and include UPD testing

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

Objective: We present low-level mosaic trisomy 21 at amniocentesis associated with a favorable fetal outcome. Case report: A 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. Conclusion: Low-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