OBJECTIVE: We present mosaic distal 10q deletion at prenatal diagnosis in a pregnancy associated with a favorable fetal outcome.
METHODS: A 40-year-old, gravida 2, para 0, woman underwent amniocentesis at 16 weeks of gestation because of advanced maternal age. Amniocentesis revealed a karyotype of 46,XY, del(10) (q26.13)[6]/46,XY[17]. Simultaneous array comparative genomic hybridization (aCGH) analysis on the DNA extracted from uncultured amniocytes showed 35% mosaicism for the 10q26.13q26.3 deletion. At 22 weeks of gestation, she underwent cordocentesis which revealed a karyotype of 46,XY,del(10) (q26.13)[16]/46,XY[24]. Prenatal ultrasound findings were normal. At 24 weeks of gestation, she was referred for genetic counseling, and repeat amniocentesis revealed a karyotype of 46,XY,del(10) (q26.13)[4]/46,XY[22]. The parental karyotypes were normal. Molecular genetic analysis on uncultured amniocytes revealed no uniparental disomy (UPD) 10 by quantitative fluorescence polymerase chain reaction (QF-PCR), arr 10q26.13q26.3 × 1.6 (40% mosaicism) by aCGH, and 29.8% (31/104 cells) mosaicism for the distal 10q deletion by interphase fluorescence in situ hybridization (FISH). The woman was advised to continue the pregnancy, and a phenotypically normal 2,900-g male baby was delivered at 39 weeks of gestation. The cord blood had a karyotype of 46,XY,del(10) (q26.13)[6]/46,XY[34], and both the umbilical cord and the placenta had the karyotype of 46,XY. When follow-up at age four months, the neonate was normal in phenotype and development. The peripheral blood had a karyotype of 46,XY,del(10) (q26.13)[5]/46,XY[35], and interphase FISH analysis on buccal mucosal cells showed 8% (8/102 cells) mosaicism for distal 10q deletion.
CONCLUSIONS: Mosaic distal 10q deletion with a normal cell line at prenatal diagnosis can be associated with a favorable fetal outcome and perinatal progressive decrease of the aneuploid cell line.

OBJECTIVE: We present low-level mosaic trisomy 21 at amniocentesis in a pregnancy with a favorable fetal outcome.
METHODS: A 38-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,+21[4]/46,XY[34]. Prenatal ultrasound findings were normal. At 27 weeks of gestation, she was referred for genetic counseling, and the cultured amniocytes had a karyotype of 47,XY,+21[2]/46,XY[26]. Quantitative fluorescent polymerase chain reaction (QF-PCR) analysis on the DNA extracted from uncultured amniocytes and parental bloods excluded uniparental disomy (UPD) 21. Interphase fluorescence in situ hybridization (FISH) analysis on uncultured amniocytes revealed 30% (30/100 cells) mosaicism for trisomy 21. Array comparative genomic hybridization (aCGH) analysis on the DNA extracted from uncultured amniocytes revealed the result of arr 21q11.2q22.3 × 2.25, consistent with 20%-30% mosaicism for trisomy 21. The parental karyotypes were normal. The woman was advised to continue the pregnancy, and a 3510-g phenotypically normal male baby was delivered at 39 weeks of gestation. Cytogenetic analysis of the cord blood, umbilical cord and placenta revealed the karyotypes of 47,XY,+21[1]/46,XY[39], 47,XY,+21[2]/46,XY[38] and 46,XY in 40/40 cells, respectively. When follow-up at age 1 year and 2 months, the neonate was normal in phenotype and development. The peripheral blood had a karyotype of 46,XY in 40/40 cells, and interphase FISH analysis on uncultured buccal mucosal cells showed 6.4% (7/109 cells) mosaicism for trisomy 21.
CONCLUSIONS: Low-level mosaic trisomy 21 at amniocentesis can be associated with cytogenetic discrepancy between cultured amniocytes and uncultured amniocytes, perinatal progressive decrease of the trisomy 21 cell line and a favorable fetal outcome.

OBJECTIVE: We 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.
METHODS: A 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].
CONCLUSIONS: Mosaic 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.

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