Prenatal diagnosis of a trisomy 7 mosaic case: CMA, CNV-seq, karyotyping, interphase FISH, and MS-MLPA, which technique to choose?

OBJECTIVE: This study aims to perform a prenatal genetic diagnosis of a high-risk fetus with trisomy 7 identified by noninvasive prenatal testing (NIPT) and to evaluate the efficacy of different genetic testing techniques for prenatal diagnosis of trisomy mosaicism. METHODS: For prenatal diagnosis of a pregnant woman with a high risk of trisomy 7 suggested by NIPT, karyotyping and chromosomal microarray analysis (CMA) were performed on an amniotic fluid sample. Low-depth whole-genome copy number variation sequencing (CNV-seq) and fluorescence in situ hybridization (FISH) were used to clarify the results further. In addition, methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) was performed to analyze the possibility of uniparental disomy(UPD). RESULTS: Amniotic fluid karyotype analysis revealed a 46, XX result. Approximately 20% mosaic trisomy 7 was detected according to the CMA result. About 16% and 4% of mosaicism was detected by CNV-seq and FISH, respectively. MS-MLPA showed no methylation abnormalities. The fetal ultrasound did not show any detectable abnormalities except for mild intrauterine growth retardation seen at 39 weeks of gestation. After receiving genetic counseling, the expectant mother decided to continue the pregnancy, and follow-up within three months of delivery was normal. CONCLUSION: In high-risk NIPT diagnosis, a combination of cytogenetic and molecular genetic techniques proves fruitful in detecting low-level mosaicism. Furthermore, the exclusion of UPD on chromosome 7 remains crucial when NIPT indicates a positive prenatal diagnosis of trisomy 7.

Low-level mosaic trisomy 21 at amniocentesis and cordocentesis in the second trimester in a pregnancy associated with positive non-invasive prenatal testing for trisomy 21, perinatal progressive decrease of the trisomy 21 cell line and a favorable fetal outcome.

OBJECTIVE: We present low-level mosaic trisomy 21 at amniocentesis and cordocentesis in a pregnancy associated with a favorable fetal outcome. CASE REPORT: A 26-year-old, primigravid woman underwent amniocentesis at 17 weeks of gestation because of positive non-invasive prenatal testing (NIPT) for trisomy 21 at 16 weeks of gestation. Amniocentesis revealed a karyotype of 47,XX,+21[3]/46,XX[17], and multiplex ligation-dependent probe amplification (MLPA) on uncultured amniocytes revealed rsa X(P095) × 2, (13, 18, 21) × 2. She underwent cordocentesis (cord blood sampling) at 21 weeks of gestation which revealed a karyotype of 47,XX,+21[2]/46,XX[48]. At 27 weeks of gestation, she was referred to our hospital for genetic counseling, and repeat amniocentesis revealed a karyotype of 46,XX in 20/20 colonies. Quantitative fluorescent polymerase chain reaction (QF-PCR) analysis on the DNA extracted from uncultured amniocytes and parental bloods excluded uniparental disomy (UPD) 21. Array comparative genomic hybridization (aCGH) analysis on the DNA extracted from uncultured amniocytes revealed arr (1-22,X) × 2, Y × 0 with no genomic imbalance. Interphase fluorescence in situ hybridization (FISH) analysis on 104 uncultured amniocytes detected one cell (1/104 = 0.9%) with trisomy 21, while the rest cells were disomy 21, compared with 0% (0/100) in the normal control. The woman was encouraged to continue the pregnancy. The pregnancy was carried to 38 weeks of gestation, and a 2771-g female baby was delivered no phenotypic abnormality. aCGH analysis on the cord blood showed arr (1-22,X) × 2, Y × 0 with no genomic imbalance. The umbilical cord had a karyotype of 47,XX,+21[3]/46,XX[37]. The placenta had a karyotype of 46,XX. When follow-up at age 3½ months, the neonate was phenotypically normal and had normal development. The peripheral blood had a karyotype of 46,XX in 40/40 cells. Interphase FISH analysis on buccal mucosal cells detected normal disomy 21 cells in 100/100 cells. CONCLUSION: Low-level mosaic trisomy 21 at amniocentesis and cordocentesis in the second trimester can be associated with perinatal progressive decrease of the trisomy 21 cell line and a favorable fetal outcome.

Low-level mosaic trisomy 21 at amniocentesis in a pregnancy 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 low-level mosaic trisomy 21 at amniocentesis in a pregnancy with a favorable fetal outcome. CASE REPORT: 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. CONCLUSION: 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.

Mosaic distal 10q deletion or 46,XY,del(10) (q26.13)/46,XY at amniocentesis and cordocentesis in a pregnancy associated with cytogenetic discrepancy between cultured amniocytes and uncultured amniocytes, perinatal progressive decrease of the aneuploid cell line and a favorable fetal outcome.

OBJECTIVE: We present mosaic distal 10q deletion at prenatal diagnosis in a pregnancy associated with a favorable fetal outcome. CASE REPORT: 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. CONCLUSION: 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.

Clinical course and genetic analysis of a case of the amniocentesis showing chromosome 6 trisomy mosaicism.

OBJECTIVE: Herein, we present a case of mosaic trisomy 6 detected by amniocentesis. CASE REPORT: Amniocentesis (G-banding) was performed at 17 weeks of gestation; the results were 47,XY,+6[3]/46,XY[12]. Fetal screening ultrasonography showed no morphological abnormalities, and the parents desired to continue the pregnancy. The infant was delivered vaginally at 39 weeks' gestation. The male infant weighed 3002 g at birth with no morphological abnormalities. G-banding karyotype analysis performed on the infant's peripheral blood revealed 46,XY[20]. FISH analysis revealed trisomy signals on chromosome 6 in 1-4 out of 100 cells from the placenta. The single nucleotide polymorphism microarray of the umbilical cord blood revealed no abnormalities. Methylation analysis of umbilical cord blood revealed no abnormalities in PLAGL1. No disorders were observed at one year of age. CONCLUSION: When amniocentesis reveals chromosomal mosaicism, it is essential to provide a thorough fetal ultrasound examination and careful genetic counseling to support the couples' decision-making.

Prenatal detection of mosaicism for a genome wide uniparental disomy cell line in a cohort of patients: Implications and outcomes.

OBJECTIVES: To investigate the prenatal detection rate of mosaicism by SNP microarray analysis, in which an individual has not one, but two, complete genomes (sets of DNA) in their body, a normal biparental line with a Genome Wide Uniparental Disomy (GWUPD) cell line was used. METHODS: This study retrospectively examines the prenatal detection of GWUPD in a cohort of ∼90,000 prenatal specimens and ∼20,000 products of conceptions (POCs) that were studied by SNP microarray. RESULTS: In total, 25 cases of GWUPD were detected; 16 cases were detected prenatally with GWUPD (∼0.018%) and 9 POCs revealed GWUPD (0.045%). The nine POC specimens presented with placental abnormalities. The 12 amniotic fluid specimens were ascertained because of abnormal ultrasound findings. Nine of 12 pregnancies had findings consistent with Beckwith-Wiedemann syndrome or because of abnormal placentas. However, three pregnancies were detected with GWUPD of maternal origin, with less common findings and demonstrated maternal origin. Four other pregnancies showed GWUPD in a chorionic villus sample, but normal findings in amniotic fluid and apparently normal fetal development. CONCLUSIONS: This cohort with GWUPD mosaicism expands our understanding of GWUPD and has implications for prenatal care and counseling. Additional studies are necessary to understand the rarer maternal GWUPD.

Mechanism of chromosomal mosaicism in preimplantation embryos and its effect on embryo development.

Aneuploidy is one of the main causes of miscarriage and in vitro fertilization failure. Mitotic abnormalities in preimplantation embryos are the main cause of mosaicism, which may be influenced by several endogenous factors such as relaxation of cell cycle control mechanisms, defects in chromosome cohesion, centrosome aberrations and abnormal spindle assembly, and DNA replication stress. In addition, incomplete trisomy rescue is a rare cause of mosaicism. However, there may be a self-correcting mechanism in mosaic embryos, which allows some mosaicisms to potentially develop into normal embryos. At present, it is difficult to accurately diagnose mosaicism using preimplantation genetic testing for aneuploidy. Therefore, in clinical practice, embryos diagnosed as mosaic should be considered comprehensively based on the specific situation of the patient.

Mosaic human preimplantation embryos and their developmental potential in a prospective, non-selection clinical trial.

Chromosome imbalance (aneuploidy) is the major cause of pregnancy loss and congenital disorders in humans. Analyses of small biopsies from human embryos suggest that aneuploidy commonly originates during early divisions, resulting in mosaicism. However, the developmental potential of mosaic embryos remains unclear. We followed the distribution of aneuploid chromosomes across 73 unselected preimplantation embryos and 365 biopsies, sampled from four multifocal trophectoderm (TE) samples and the inner cell mass (ICM). When mosaicism impacted fewer than 50% of cells in one TE biopsy (low-medium mosaicism), only 1% of aneuploidies affected other portions of the embryo. A double-blinded prospective non-selection trial (NCT03673592) showed equivalent live-birth rates and miscarriage rates across 484 euploid, 282 low-grade mosaic, and 131 medium-grade mosaic embryos. No instances of mosaicism or uniparental disomy were detected in the ensuing pregnancies or newborns, and obstetrical and neonatal outcomes were similar between the study groups. Thus, low-medium mosaicism in the trophectoderm mostly arises after TE and ICM differentiation, and such embryos have equivalent developmental potential as fully euploid ones.

Complex mosaic blastocysts after preimplantation genetic testing: prevalence and outcomes after re-biopsy and re-vitrification.

RESEARCH QUESTION: What is the incidence of complex mosaic in preimplantation genetic testing (PGT) blastocysts and can it be managed in clinical practice? DESIGN: A retrospective study of PGT cycles conducted between January 2018 and October 2019 at a single centre. Biopsies of blastocysts were collected and analysed by next-generation sequencing (NGS). Complex mosaic blastocysts were defined as those with three or more mosaic chromosomes. The cryopreserved complex mosaic blastocysts underwent a second round of biopsy, NGS analysis and vitrification. The euploid blastocysts identified by the re-biopsy were warmed again for embryo transfer. The main outcomes included the prevalence of the complex mosaic and the ongoing pregnancy rate. RESULTS: The prevalence of the complex mosaic was 2.4% (437/17,979). The prevalence of the complex mosaic was not associated with maternal age and morphological quality. A total of 89 complex mosaic blastocysts underwent re-biopsy and 96.6% (86/89) survived the first warming. For the re-biopsy samples, 61.6% (53/86) were euploid. The poor-quality blastocysts had higher rates of aneuploidy compared with good-quality blastocysts. The survival rate for blastocysts undergoing the second warming was 100% (18/18) and resulted in an ongoing pregnancy rate of 38.9% (7/18) as well as the birth of six healthy infants. CONCLUSION: Re-biopsy may rescue blastocysts with development potential for transfer and improve the cumulative pregnancy rate per stimulation cycle in patients containing complex mosaic blastocysts.

Prenatal diagnosis of recurrent mosaic ring chromosome 13 of maternal origin.

OBJECTIVE: We present prenatal diagnosis of recurrent mosaic ring chromosome 13 [r(13)] of maternal origin. CASE REPORT: A 27-year-old woman underwent amniocentesis at 17 weeks of gestation because of a past history of fetal abnormality caused by mosaic r(13) in the previous fetus associated with fetal intrauterine growth restriction (IUGR), a karyotype of 46,XY,r(13)[23]/45,XY,-13[10]/46,XY,idic r(13)[2] and a maternal origin of abnormal r(13). The parental karyotypes were normal. During this pregnancy, amniocentesis revealed a karyotype of 46,XX,r(13)[12]/45,XX,-13[8] and a 22.80-Mb deletion of chromosome 13q31.3-q34. The pregnancy was subsequently terminated, and a malformed fetus was delivered with craniofacial dysmorphism. Repeat amniocentesis revealed a karyotype of 46,XX,r(13)(p11.1q31)[18]/45,XX,-13[12]. The placenta had a karyotype of 46,XX,r(13)(p11.1q31)[27]/45,XY,-13[13]. Polymorphic DNA marker analysis using the DNA derived from the parental bloods and umbilical cord confirmed a maternal origin of the abnormal r(13). CONCLUSION: Prenatal diagnosis of mosaic r(13) in consecutive pregnancies should raise a suspicion of parental gonadal mosaicism, and polymorphic DNA marker analysis is useful for determination of the parental origin of recurrent aneuploidy under such a circumstance.

Mosaic Xq duplication, or 46,X,der(X)dup(X)(q22.1q22.2)dup(X)(q25q22.3)/ 46,XX at amniocentesis in a pregnancy with a favorable outcome.

OBJECTIVE: We present mosaic Xq duplication, or 46,X,der(X)dup(X)(q22.1q22.2)dup(X)(q25q22.3)/46,XX at amniocentesis in a pregnancy with a favorable outcome. CASE REPORT: A 40-year-old woman underwent amniocentesis at 16 weeks of gestation because of advanced maternal age. Amniocentesis revealed a result of 46,X,der(X)dup(X)(q22.1q22.2)dup(X)(q25q22.3)[7]/46,XX[20]. Simultaneous array comparative genomic hybridization (aCGH) analysis on the DNA extracted from uncultured amniocytes revealed the result of arr (1-22, X) × 2. Cytogenetic analysis on maternal blood revealed a karyotype of 46,XX. At 22 weeks of gestation, she underwent repeat amniocentesis which revealed a karyotype of 46,XX in 22/22 colonies of cultured amniocytes and an aCGH result of (1-22, X) × 2 in the uncultured amniocytes. Prenatal ultrasound findings were unremarkable. The parents decided to continue the pregnancy, and a healthy female baby was delivered at 39 weeks of gestation with a body weight of 3510 g and a body length of 49 cm. The cord blood had a karyotype of 46,X,der(X)dup(X)(q22.1q22.2)dup(X)(q25q22.3)[3]/46,XX[37]. At age two months, interphase fluorescence in situ hybridization (FISH) analysis on buccal mucosal cells showed Xq duplication signals in 1.25% (1/80 cells), compared with 0% (0/90 cells) in the normal control. At age nine months, the neonate had normal physical and psychomotor development. Her body weight was 9.6 Kg (85th - 97th centile), and body length was 72 cm (50th - 85th centile). Cytogenetic analysis of peripheral blood revealed a karyotype of 46,X,der(X)dup(X) (q22.1q22.2)dup(X)(q25q22.3)[1]/46,XX[39]. Interphase FISH analysis on 100 buccal mucosal cells revealed no abnormal signal. CONCLUSION: In case of mosaicism for an Xq duplication with a normal euploid cell line at amniocentesis, the in-vitro culture process of amniocytes may cause over-estimation of the mosaic level for the aberrant chromosome because of culture artifacts, and the abnormal cell line can decline after birth.

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

OBJECTIVE: We 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 REPORT: A 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. CONCLUSION: Cytogenetic 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.

Prenatal diagnosis of mosaicism for double aneuploidy of 47,XXY and trisomy 7 (48,XXY,+7) at amniocentesis in a pregnancy with a favorable outcome.

OBJECTIVE: We present prenatal diagnosis of mosaicism for double aneuploidy of 47, XXY and trisomy 7 (48,XXY,+7) at amniocentesis in a pregnancy with a favorable outcome. CASE REPORT: A 33-year-old woman underwent amniocentesis at 17 weeks of gestation because of an increased risk for Down syndrome in maternal serum screening. Amniocentesis revealed a karyotype of 48,XXY,+7[8]/46,XY[16]. Simultaneous array comparative genomic hybridization (aCGH) analysis on uncultured amniocytes revealed the result of arr [GRCh37] (7) × 3 [0.54], (X) × 2 [0.52], (Y) × 1, compatible with trisomy 7 mosaicism and Klinefelter syndrome mosaicism. The parental karyotypes and prenatal ultrasound findings were normal. Repeat amniocentesis performed at 23 weeks of gestation revealed a karyotype of 48,XXY,+7[13]/46,XY[7]. Simultaneous molecular cytogenetic analyses on uncultured amniocytes revealed 30% mosaicism for 48,XXY,+7 by aCGH and 37% (37/100 cells) mosaicism for trisomy 7 and disomy X by interphase fluorescence in situ hybridization (FISH) analysis. Polymorphic DNA marker analysis excluded uniparental disomy (UPD) 7 and indicated a maternal origin of the chromosome aberration. The pregnancy was continued to 39 weeks of gestation, and a 3070-g healthy male baby was delivered. The cord blood had a karyotype of 46,XY, the umbilical cord had a karyotype of 48,XXY,+7[3]/46,XY[37], and the placenta had a karyotype of 48,XXY,+7. At age one month, the neonate was phenotypically normal, and interphase FISH analysis revealed 4.8% (5/105 cells) mosaicism on buccal mucosal cells and 8.9% (8/90 cells) mosaicism on urinary cells for trisomy 7 and disomy X, compared with 2% in normal control. Interphase FISH analysis on buccal mucosal cells at age two months revealed normal findings in 100/100 cells. CONCLUSION: Mosaic 48,XXY,+7 at amniocentesis without UPD 7 can be associated with a favorable fetal outcome. Cytogenetic discrepancy between cultured amniocytes and uncultured amniocytes may occur in mosaic 48,XXY,+7 at amniocentesis.

Prenatal diagnosis of a fetus with mosaic ring chromosome 13: Case report and review of the literature.

OBJECTIVE: To diagnose the ring chromosome 13 (r(13)) in a fetus, and analyze the genotype-phenotype correlation. CASE REPORT: A 26-year-old woman who was second pregnancy, underwent amniocentesis at 18 weeks of gestation because of the increased nuchal translucency (NT). Prenatal ultrasound showed the NT thickness was 3.5 mm at 12+1 weeks of gestation and nuchal fold (NF) was 6.1 mm at 18 weeks of gestation, and amniotic fluid karyotype analysis revealed mosaic r(13). CMA detected a 16.293 Mb duplication at 13q21.32q31.1 and 31.303 Mb deletion at 13q31.1q34. CONCLUSION: R(13) is a very rare chromosomal abnormality. Cytogenetic examination combined with CMA can provide accurate diagnosis and effective information for genetic counseling.

No pre-zygotic isolation mechanisms between Schistosoma haematobium and Schistosoma bovis parasites: From mating interactions to differential gene expression.

Species usually develop reproductive isolation mechanisms allowing them to avoid interbreeding. These preventive barriers can act before reproduction, "pre-zygotic barriers", or after reproduction, "post-zygotic barriers". Pre-zygotic barriers prevent unfavourable mating, while post-zygotic barriers determine the viability and selective success of the hybrid offspring. Hybridization in parasites and the underlying reproductive isolation mechanisms maintaining their genetic integrity have been overlooked. Using an integrated approach this work aims to quantify the relative importance of pre-zygotic barriers in Schistosoma haematobium x S. bovis crosses. These two co-endemic species cause schistosomiasis, one of the major debilitating parasitic diseases worldwide, and can hybridize naturally. Using mate choice experiments we first tested if a specific mate recognition system exists between both species. Second, using RNA-sequencing we analysed differential gene expression between homo- and hetero-specific pairing in male and female adult parasites. We show that homo- and hetero-specific pairing occurs randomly between these two species, and few genes in both sexes are affected by hetero-specific pairing. This suggests that i) mate choice is not a reproductive isolating factor, and that ii) no pre-zygotic barrier except spatial isolation "by the final vertebrate host" seems to limit interbreeding between these two species. Interestingly, among the few genes affected by the pairing status of the worms, some can be related to pathways affected during male and female interactions and may also present interesting candidates for species isolation mechanisms and hybridization in schistosome parasites.

Prenatal diagnosis of low-level mosaicism for a small supernumerary marker chromosome derived from chromosome 9q (9q13-q21.33) in a pregnancy with a favorable outcome, and cytogenetic discrepancy between cultured amniocytes and uncultured amniocytes.

OBJECTIVE: We present prenatal diagnosis of low-level mosaicism for a small supernumerary marker chromosome (sSMC) derived from chromosome 9q (9q13-q21.33) in a pregnancy with a favorable outcome, and cytogenetic discrepancy between cultured amniocytes and uncultured amniocytes. CASE REPORT: A 36-year-old, primigravid woman underwent amniocentesis at 17 weeks of gestation because of advanced maternal age. Cytogenetic analysis on cultured amniocytes revealed a karyotype of 46,XY in 20/20 colonies. Simultaneous array comparative genomic hybridization (aCGH) on the DNA extracted from uncultured amniocytes revealed 30% mosaicism for a de novo 20.3-Mb gene dosage increase at 9q13-q21.33. Repeat amniocentesis and cordocentesis were performed at 21 weeks of gestation. Cytogenetic analysis on cord blood revealed a karyotype of 47,XY,+mar [3]/46,XY [37]. aCGH analysis of cord blood revealed 7.5% mosaicism for a 17.15-Mb gene dosage increase at 9q21.11-q21.33. aCGH analysis of uncultured amniocytes revealed 11.7% mosaicism for a 17.15-Mb gene dosage increase at 9q21.11-q21.33. Polymorphic DNA marker analysis excluded uniparental disomy 9. The parental karyotypes were normal. The pregnancy was carried to 37 weeks of gestation, and a 2955-g phenotypically normal male baby was delivered. At birth, the cord blood had a karyotype of 47,XY,+mar [3]/46,XY [37], the placenta had a karyotype of 47,XY,+mar [10]/46,XY [30], and the umbilical cord had a karyotype of 47,XY,+mar [14]/46,XY [36]. aCGH analysis on the DNA extracted from cord blood at birth revealed no genomic imbalance. Interphase fluorescence in situ hybridization analysis on buccal mucosal cells at age two months detected 3.8% (4/106 cells) mosaicism for the sSMC, compared with 2% (2/100 cells) in the normal control. The neonate had normal physical development at age two months. CONCLUSION: Cytogenetic discrepancy between cultured amniocytes and uncultured amniocytes may exist in the pregnancy with fetal mosaic sSMC. Low-level mosaicism for an sSMC derived from chromosome 9q13-q21.33 at prenatal diagnosis can be associated with a favorable outcome in the fetus.

Prenatal diagnosis of a 15q11.2-q14 deletion of paternal origin associated with increased nuchal translucency, mosaicism for de novo multiple unbalanced translocations involving 15q11-q14, 5qter, 15qter, 17pter and 3qter and Prader-Willi syndrome.

OBJECTIVE: We present prenatal diagnosis of a 15q11.2-q14 deletion of paternal origin associated with increased nuchal translucency (NT), mosaicism for de novo multiple unbalanced translocations involving 15q11-q14, 5qter, 15qter, 17pter and 3qter, and Prader-Willi syndrome (PWS). CASE REPORT: A 32-year-old, primigravid woman underwent amniocentesis at 18 weeks of gestation because of an increased NT thickness of 5.6 mm and abnormal maternal serum screening results in the first trimester. The pregnancy was conceived by in vitro fertilization and embryo transfer. Amniocentesis revealed a karyotype of 45,XX,der(5)t(5;15)(q35;q14),-15 [16]/45,XX,-15,der(17)t(15;17)(q14;p13)[3]/45,XX,der(15)t(15;15)(q35;q14),-15[2]. The parental karyotypes were normal. Prenatal ultrasound findings were unremarkable. Array comparative genomic hybridization (aCGH) analysis on the DNA extracted from cultured amniocytes revealed the result of arr 15q11.2q14 (22,765,628-38,651,755) × 1.0 [GRCh37 (hg19)] with a 15.886-Mb 15q11.2-q14 deletion encompassing TUBGCP5, CYFIP1, NIPA2, NIPA1, SNRPN, SNURF, SNORD116-1, IPW, UBE3A, ACTC1 and MEIS2. The pregnancy was subsequently terminated, and a malformed fetus with facial dysmorphism was delivered. The cord blood had a karyotype of 45,XX,der(5)t(5;15)(q35;q14),-15[46]/45,XX,der(3)t(3;15) (q29;q14),-15[2]/45,XX,-15,der(17)t(15;17)(q14;p13)[2]. The placenta had a karyotype of 45,XX,der(5) t(5;15)(q35;q14),-15. Polymorphic DNA marker analysis confirmed a paternal origin of the proximal 15q deletion. CONCLUSION: Increased NT and abnormal maternal serum screening results may prenatally be associated with PWS. Chromosome 15 rearrangements in PWS include mosaicism for de novo multiple unbalanced translocations.

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

OBJECTIVE: We present low-level mosaicism for trisomy 16 at amniocentesis in a pregnancy associated with intrauterine growth restriction (IUGR) and a favorable outcome. CASE REPORT: A 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. CONCLUSION: Cytogenetic 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.