Partial monosomy 13q (13q21.32--->qter) and partial trisomy 8p (8p1--->pter) presenting with anencephaly and increased nuchal translucency: array comparative genomic hybridization characterization

ObjectiveTo present array comparative genomic hybridization (aCGH) characterization of partial monosomy 13q (13q21.32→qter) and partial trisomy 8p (8p12→pter) presenting with anencephaly and increased nuchal translucency (NT).Case ReportA 34-year-old primigravid woman was referred to the hospital at 12 weeks of gestation for termination of the pregnancy because of major structural abnormalities of the fetus. Prenatal ultrasound revealed a malformed fetus with anencephaly and an increased NT thickness of 5 mm at 12 weeks of gestation. Cytogenetic analysis of the fetus revealed a derivative chromosome 13. The mother was subsequently found to carry a balanced reciprocal translocation between 8p12 and 13q21. Bacterial artificial chromosome-based aCGH using fetal DNA demonstrated partial trisomy 8p and partial monosomy 13q [arr cgh 8p23.3p12 (RP11-1150M5→RP11-1145H12)×3, 13q21.32q34 (RP11-326B4→RP11-450H16)×1]. Oligonucleotide-based aCGH showed a 36.7-Mb duplication of distal 8p and a 48.4-Mb deletion of distal 13q. The fetal karyotype was 46,XY,der(13) t(8;13)(p12;q21.32)mat. The maternal karyotype was 46,XX,t(8;13)(p12;q21.32).ConclusionThe 13q deletion syndrome can be associated with neural tube defects and increased NT in the first trimester. Prenatal sonographic detection of neural tube defects should alert chromosomal abnormalities and prompt cytogenetic investigation, which may lead to the identification of an unexpected parental translocation involving chromosomal segments associated with neural tube development.     

Prenatal diagnosis of partial monosomy 18p(18p11.2-->pter) and trisomy 21q(21q22.3-->qter) with alobar holoprosencephaly and premaxillary agenesis

A prenatal diagnosis of partial monosomy 18p(18p11.2-->pter) and trisomy 21q(21q22.3-->qter) in a fetus with alobar holoprosencephaly (HPE) and premaxillary agenesis (PMA) but without the classical Down syndrome phenotype is reported. A 27-year-old primigravida woman was referred for genetic counselling at 21 weeks' gestation due to sonographic findings of craniofacial abnormalities. Level II ultrasonograms manifested alobar HPE and median orofacial cleft. Cytogenetic analysis and fluorescence in situ hybridization (FISH) on cells obtained from amniocentesis revealed partial monosomy 18p and a cryptic duplication of 21q,46,XY,der(18)t(18;21)(p11.2;q22.3), resulting from a maternal t(18;21) reciprocal translocation. The breakpoints were ascertained by molecular genetic analysis. The pregnancy was terminated. Autopsy showed alobar HPE with PMA, pituitary dysplasia, clinodactyly and classical 18p deletion phenotype but without the presence of major typical phenotypic features of Down syndrome. The phenotype of this antenatally diagnosed case is compared with those observed in six previously reported cases with monosomy 18p due to 18;21 translocation. The present study is the first report of concomitant deletion of HPE critical region of chromosome 18p11.3 and cryptic duplication of a small segment of distal chromosome 21q22.3 outside Down syndrome critical region. The present study shows that cytogenetic analyses are important in detecting chromosomal aberrations in pregnancies with prenatally detected craniofacial abnormalities, and adjunctive molecular investigations are useful in elucidating the genetic pathogenesis of dysmorphism.     

Prenatal findings and molecular cytogenetic analyses of partial trisomy 12q (12q24.32-->qter) and partial monosomy 21q (21q22.2-->qter)

OBJECTIVES: To present the prenatal findings and molecular cytogenetic analyses of partial trisomy 12q and partial monosomy 21q, and a review of the literature. METHODS: Amniocentesis was performed at 23 gestational weeks in a 33-year-old woman because of abnormal sonographic findings. Amniocentesis revealed a derivative chromosome 21, or der(21), with a deletion on the region of 21q22.2 and an addendum of a small chromosomal segment of unknown origin. The maternal karyotype was subsequently found to be 46,XX,t(12;21)(q24.32;q22.2). Level II ultrasound showed microcephaly, micrognathia, a ventricular septal defect, and rocker-bottom feet. The pregnancy was terminated. A malformed infant was delivered without the phenotype of holoprosencephaly (HPE). Fluorescence in situ hybridization (FISH) and polymorphic DNA markers were used to investigate the involved chromosomal segments. RESULTS: FISH study showed the absence of the signal of 21q subtelomeric probe and the presence of the signal of 12q subtelomeric probe in the der(21).The fetal karyotype was 46,XY,der(21) t(12;21)(q24.32;q22.2)mat. Genetic marker analysis showed a deletion at 21q22.2 and a breakpoint between D21S156 (present) and D21S1245 (absent). The deleted segment was measured about 4.5 Mb encompassing the HPE critical region. CONCLUSIONS: Molecular genetic analyses help in determining the prenatally detected unbalanced cryptic translocation as well as parental balanced subtle translocation. A duplication of 12q24.32-->qter and a deletion of 21q22.2-->qter may be associated with prenatal sonographic findings of microcephaly, borderline ventriculomegaly and cerebellar hypoplasia, micrognathia, a ventricular septal defect, and rocker-bottom feet. Haploinsufficiency of the HPE critical region at 21q22.3 may not cause an HPE phenotype.     

Perinatal findings and molecular cytogenetic analyses of de novo interstitial deletion of 9q (9q22.3-->q31.3) associated with Gorlin syndrome

OBJECTIVES: To present the perinatal findings and the molecular cytogenetic analyses of a de novo interstitial deletion of 9q (9q22.3-->q31.3) associated with Gorlin syndrome. METHODS: Amniocentesis was performed at 18 weeks' gestation on a 27-year-old woman at a community hospital because of a high Down syndrome risk of 1/178, a low maternal serum alpha-fetoprotein (MSAFP) level of 0.66 multiples of the median (MoM), and a high maternal serum human chorionic gonadotrophin (MShCG) level of 3.13 MoM. The karyotype was initially determined to be 46,XY. However, fetal macrocephaly and overgrowth were found at 30 weeks' gestation. Postnatally, the infant manifested characteristic features of Gorlin syndrome. High-resolution chromosomal bandings of the peripheral blood lymphocytes, polymorphic DNA marker analysis to determine the parental origin of the deletion, array comparative genomic hybridization (CGH) to determine the extent of the chromosomal deletion, and fluorescence in situ hybridization (FISH) to determine the deletion of the PTCH gene were performed. RESULTS: The 850-band level of resolution showed an interstitial deletion of 9q (9q22.3-->q31.3). The parental karyotypes were normal. The karyotype of the proband was 46,XY,del(9)(q22.3q31.3)de novo. Polymorphic DNA marker analysis revealed that the deletion was of paternal origin. Array CGH revealed that the deleted region was about 12 Mb, encompassing the segment from 9q22.32 to 9q31.3. FISH analysis using the BAC probe RP11-34D4 and the probe RP11-43505 indicated the deletion of the PTCH gene. CONCLUSIONS: Fetuses with an interstitial deletion of 9q (9q22.3-->q31.3) may be associated with a low level of MSAFP and a high level of MShCG in the second trimester, and sonographic findings of overgrowth and macrocephaly in the third trimester.     

Sacrococcygeal teratoma in a fetus with prenatally diagnosed partial trisomy 10q (10q24.3-->qter) and partial monosomy 17p (p13.3-->pter)

OBJECTIVE: Clinical features of the distal 10q trisomy syndrome consist of mental retardation, facial dysmorphism and renal and cardiac anomalies. The presence of a sacrococcygeal teratoma (SCT) in a fetus with distal 10q trisomy has not been reported yet. METHODS: A 33-year-old, G5, P2 woman with a singleton pregnancy was referred to our clinic at 24 weeks of gestation for further evaluation of a fetal sacral exophytic mass. Detailed fetal sonographic examination together with chromosomal analysis by amniocentesis was performed. RESULTS: The scan revealed a large SCT together with a persistent right umbilical vein, cardiomegaly, bilateral mild hydronephrosis and intrauterine growth retardation. The fetal karyotype showed distal 10q trisomy (10q24.3-->qter) distal monosomy 17 (p13-->pter). The fetus died after a preterm delivery at 28 weeks of gestation. Postnatal examination confirmed the prenatal findings and added the typical facial features of this syndrome, which consisted of prominent forehead, small nose with depressed nasal bridge, micrognathia and bow-shaped mouth. CONCLUSION: This case provides further evidence of a possible association between chromosomal aberrations in SCTs.     

Detection of paternal origin of fetal de novo rea(21q;21q) down syndrome in a pregnancy of a young woman associated with an abnormal first-trimester maternal serum screening result

ObjectiveWe present detection of paternal origin of fetal de novo rea(21q;21q) Down syndrome in a pregnancy of a young woman associated with an abnormal first-trimester maternal serum screening result.Case reportA 26-year-old, gravida 2, para 1, woman underwent amniocentesis at 17 weeks of gestation because of an abnormal first-trimester screening result of 1/139 risk of Down syndrome calculated by 3.109 multiples of the median (MoM) of maternal serum free β-hCG and 0.454 MoM of pregnancy associated plasma protein-A (PAPP-A). Her husband was 29 years old, and the couple had a 1-year-old healthy daughter. Amniocentesis revealed a karyotype of 46,XX,+21,der(21;21)(q10;q10). The pregnancy was terminated at 19 weeks of gestation, and a malformed fetus was delivered. The parental karyotypes were normal. Postnatal analysis of the umbilical cord showed a karyotype of 46,XX,+21,der(21;21) (q10;q10). Polymorphic DNA marker analysis on the DNA extracted from parental bloods and umbilical cord confirmed a paternal origin of the de novo rea(21q;21q) Down syndrome.ConclusionPrenatal diagnosis of de novo rea(21q;21q) Down syndrome should include a polymorphic DNA marker analysis of the parental origin, and the acquired information is useful for genetic counseling of the recurrence of unbalanced rea(21q;21q) offspring and the determination of low-level tissue mosaicism or gonadal mosaicism in one of the parents.     

Prenatal diagnosis and molecular cytogenetic characterization of a de novo deletion of 4q34.1→qter associated with low PAPP-A and low PlGF in the first-trimester maternal serum screening,congenital heart defect on fetal ultrasound and a false negative non-invasive prenatal testing (NIPT) result

ObjectiveWe present prenatal diagnosis and molecular cytogenetic characterization of a de novo deletion of 4q34.1→qter associated with low pregnancy associated plasma protein-A (PAPP-A) and low placental growth factor (PlGF) in the first-trimester maternal serum screening, congenital heart defect (CHD) on fetal ultrasound and a false negative non-invasive prenatal testing (NIPT) result.Case ReportA 40-year-old, primigravid woman underwent amniocentesis at 20 weeks of gestation because of advanced maternal age. This pregnancy was conceived by in vitro fertilization (IVF) and embryo transfer (ET). First-trimester maternal serum screening at 12 weeks of gestation revealed low PAPP-A [0.349 multiples of the median (MoM)] and low PlGF (0.299 MoM) and showed a risk for fetal trisomy 21 and trisomy 13. However, NIPT detected no genomic imbalance and a normal result. Nevertheless, level II ultrasound revealed ventricular septal defect, single umbilical artery and a small brain midline cyst. Amniocentesis revealed a karyotype of 46,XX,del(4)(q34.1) and a 17.8-Mb deletion of 4q34.1q.35.2 on array comparative genomic hybridization (aCGH) analysis. The parental karyotypes were normal. The pregnancy was terminated at 23 weeks of gestation, and a malformed fetus was delivered with craniofacial dysmorphism. Postnatal cytogenetic analysis of the placenta confirmed the prenatal diagnosis. There was a 17.8-Mb deletion of 4q34.1q.35.2 encompassing the genes of HAND2, SORBS2 and DUX4. Polymorphic DNA marker analysis on the parental bloods and cord blood showed a paternal origin of the deletion.ConclusionAn abnormal first-trimester maternal serum screening result along with abnormal fetal ultrasound should alert the possibility of fetal aneuploidy, and amniocentesis is indicated even in the presence of a normal NIPT result.     

De novo unbalanced translocation resulting in monosomy for distal 5p (5p14.1 → pter) and 14q (14q32.31 → qter) associated with fetal nuchal edema,microcephaly, intrauterine growth restriction,and single umbilical artery: Prenatal diagnosis and molecular cytogenetic characterization

ObjectiveTo present prenatal diagnosis of partial monosomy 5p (5p14.1 → pter) and partial monosomy 14q (14q32.31 → qter).Materials and MethodsA 33-year-old woman underwent amniocentesis at 20 weeks of gestation because of abnormal fetal ultrasound. Amniocentesis revealed a dicentric chromosome of dic(5;14). Level II ultrasound at 23 weeks of gestation revealed a fetus with intrauterine growth restriction, microcephaly, nuchal edema, a single umbilical artery, and fetal biometry equivalent to 19 weeks. At 23 weeks of gestation, she requested repeated amniocentesis. Whole-genome array comparative genomic hybridization on uncultured amniocytes was performed. Quantitative fluorescent polymerase chain reaction analysis was performed on uncultured cord blood and parental blood. A fetus was delivered with microcephaly, low-set ears, hypertelorism, depressed nasal bridge, increased nuchal fold, and a single umbilical artery.ResultsThe fetal karyotype was 45,XX,dic(5;14)(p14.1;q32.31)dn. Whole-genome array comparative genomic hybridization analysis on uncultured amniocytes detected arr 5p15.33p14.1 (36,238-28,798,509)×1 and arr 14q32.31q32.33 (101,508,967-107,349,540)×1. Quantitative fluorescent polymerase chain reaction assays showed that the aberrant dic(5;14) was from paternal origin.ConclusionConcomitant occurrence of monosomy for distal 5p and distal 14q my present nuchal edema, microcephaly, IUGR, and single umbilical artery on prenatal ultrasound.     

Chromosomal abnormalities associated with a single umbilical artery.

A single umbilical artery was seen in 10 out of 117 cytogenetically abnormal pregnancies. The abnormal karyotypes found to be associated with a single umbilical artery were trisomy 18 (n = 5), monosomy X (n = 2), triploidy (n = 1), sex chromosome (47,XYY; n = 1) and translocation (46t(X,5)(q13p15);n = 1). With the exception of the translocation case, all cases with a single umbilical artery had anatomical defects which were detectable ultrasonographically. This suggests that a single umbilical artery alone is not an indication for prenatal fetal karyotyping.     

Perinatal findings and molecular cytogenetic analysis of de novo partial trisomy 16q (16q22.1-->qter) and partial monosomy 20q (20q13.3-->qter)

OBJECTIVES: To present the perinatal findings and molecular cytogenetic analysis of de novo partial trisomy 16q and partial monosomy 20q and a review of the literature. CASE AND METHODS: Obstetric ultrasound at 33 weeks' gestation revealed intrauterine growth restriction (IUGR) and dolichocephaly in a 27-year-old primigravid woman. Prenatal cytogenetic diagnosis was not offered because of the late stage of gestation. A 2800-g male baby was delivered at 41 weeks' gestation by cesarean section because of fetal distress. The infant postnatally presented characteristic craniofacial dysmorphism, hypotonia, cleft palate, congenital heart defects, a subependymal cyst, and hypospadia. Cytogenetic analysis revealed an additional material attached to the terminal region of chromosome 20q. The parental karyotypes were normal. Spectral karyotyping (SKY), fluorescence in situ hybridization (FISH), and polymorphic DNA markers were used to investigate the origin of the de novo aberrant chromosome. RESULTS: SKY using 24-color probes, FISH using specific 16p, 16q, 20 centromeric, and 20q telomeric probes, and polymorphic DNA marker analysis confirmed maternal origin of the duplication of distal 16q and the deletion of terminal 20q. Karyotype of the proband was designated as 46,XY.ish der(20)t(16;20)(q22.1;q13.3)(SKY+,16qTEL+,20qTEL-). CONCLUSIONS: Partial trisomy 16q (16q22.1-->qter) and partial monosomy 20q (20q13.3-->qter) may be associated with the perinatal findings of IUGR, dolichocephaly, hypotonia, cleft palate, congenital heart defects, a subependymal cyst, and hypospadia. SKY, FISH, and genetic marker studies help in delineating the parental origin and the regions of the deletion and duplication in the de novo unbalanced translocation.     

Prenatal diagnosis of de novo t(2;18;14)(q33.1;q12.2;q31.2), dup(5)(q34q34), del(7)(p21.1p21.1), and del(10)(q25.3q25.3) and a review of the prenatally ascertained de novo apparently balanced complex and multiple chromosomal rearrangements

OBJECTIVES: To present the prenatal diagnosis of a de novo complex chromosomal rearrangement (CCR) associated with de novo interstitial deletions and duplication and to review the literature. CASE AND METHODS: Amniocentesis was performed at 18 weeks' gestation because of an increased risk for Down syndrome based on maternal serum alpha-fetoprotein and human chorionic gonadotrophin screening. Amniocentesis revealed a karyotype of 46,XY,t(2;18;14)(q33.1;q12.2;q31.2),dup(5)(q34q34),del(7)(p21.1p21.1), del(10)(q25.3q25.3). The parental karyotypes were normal. The pregnancy was terminated. The fetus manifested facial dysmorphism, clinodactyly of both hands, and hypoplasia of the left great toe. Spectral karyotyping (SKY), cytogenetic polymorphism, and polymorphic DNA markers were used to investigate the imbalances and the origin of the de novo aberrant chromosomes. RESULTS: SKY showed a three-way CCR. Cytogenetic polymorphism investigation of the derivative chromosome 14 of the fetus and the parental chromosomes 14 determined the maternal origin of the translocation. Polymorphic DNA marker analysis confirmed the maternal origin of the de novo interstitial deletions and duplication. No cryptic imbalance at or near the breakpoints of the CCR was detected by the molecular analysis. CONCLUSIONS: De novo apparently balanced CCRs may be associated with imbalances in other chromosomes. We suggest further investigation and re-evaluation of cryptic or subtle imbalances in all cases classified as de novo apparently balanced CCRs.     

Familial cryptic translocation with deletion 4q33-->4qter and duplication 7q34-->7qter in brothers with mental retardation,macrocephaly and iris coloboma

The association of moderate mental retardation, behavioural problems, macrocephaly, dysmorphic features with iris coloboma, and supernumerary nipples was observed in two brothers with a terminal deletion 4q33-->4qter and a terminal duplication 7q34-->7qter. The aberration was detected by subtelomere FISH screening and (probably) resulted from a cryptic familial translocation (4;7)(q33;q34).     

Molecular cytogenetic characterization of a de novo unbalanced translocation leading to trisomy 17q25-->qter and monosomy 18p11.3-->pter in a girl with dysmorphic features

An 18-year-old, gravida 1 underwent percutaneous umbilical blood sampling (PUBS) because of positive triple screen, oligohydramnios and markedly short fetal bones. Chromosome analysis showed an abnormal chromosome 18 with unidentified chromatin at the end of the p-arm. Parental karyotypes were normal. FISH analyses with wcp18 showed additional material of unknown origin on the derivative chromosome 18. Further FISH analysis with subtelomeric probes showed normal signals for the long arm of chromosome 18 (18q23) while no signals were observed for the short arm (18p11.32). These findings were confirmed using a YAC probe from the short arm of 18. The infant was delivered at 30 weeks of gestation. At age 3 months, she was developmentally delayed and has multiple dysmorphic features. Further molecular cytogenetic studies including M-FISH and subtelomere probes showed that the additional material on chromosome 18 consisted of the distal 17q25-->qter region. Based on these studies the karyotype has been interpreted as 46,XX,der(18)t(17;18)(q25;p11.32). To the best of our knowledge, this is the first report of partial monosomy 18p and partial trisomy 17q in a patient with no major CNS malformations. This case shows the importance of molecular cytogenetic techniques in detailed characterization of de novo chromosome rearrangements.     

Bilateral renal agenesis and fetal ascites in association with partial trisomy 13 and partial trisomy 16 due to a 3:1 segregation of maternal reciprocal translocation t(13;16)(q12.3; p13.2).

A female fetus with bilateral renal agenesis and fetal ascites was found to have partial trisomy 13 (pter-q12.3) and partial trisomy 16 (p13.2-pter), 47,XX,+der(13)t(13;16)(q12.3; p13.2)mat. The chromosomal aberration was due to a 3:1 segregation with tertiary trisomy transmitted from a maternal reciprocal translocation 13;16. Prenatal ultrasound of a 29-year-old, gravida 2, para 0 woman at 22 gestational weeks showed fetal ascites, severe oligohydramnios and non-visualization of fetal urinary bladder and kidneys. The pregnancy was terminated. At delivery, the proband displayed dysmorphic features of hypertelorism, a prominent glabella, epicanthic fold, a stubby nose with a depressed nasal bridge, anteverted nares, thin lips, micrognathia, low-set ears, a short neck and a distended abdomen. Necropsy confirmed bilateral renal agenesis and ascites. A cytogenetic study performed on fibroblasts obtained from the proband's skin revealed an extra supernumerary chromosome. The mother was later found to have a reciprocal translocation. Fluorescence in situ hybridization for a submicroscopic deletion in chromosome 22q11 in the proband was negative. The parents had no urological anomalies. Our observation further extends the clinical spectrum associated with proximal trisomy 13q and distal trisomy 16p. We suggest prenatal cytogenetic analysis in fetuses with urological anomalies, including renal agenesis, to uncover underlying genetic disorders.     

Prenatal diagnosis of jumping translocation involving chromosome 22 with ultrasonographic findings

We report on the prenatal diagnosis and ultrasonographic findings of a second-trimester fetus with jumping translocation involving chromosome 22. A 28-year-old gravida 2, partus 1, Turkish woman was referred for genetic counselling and ultrasonographic examination at 18 weeks' gestation because of a high risk of trisomy 21 in triple test. Prenatal ultrasonography showed tetralogy of Fallot with a diverticular dilatation of the pulmonary artery, flattened brow, complete absence of the right upper limb, hypospadias, oligodactyly (three digits) in left hand and in both feet, and hyperechogenic abdominal foci. Amniocentesis revealed a karyotype of 46,XY[4]/46,XY,-8,+ der(8),t(8;22)(q24.3;q11.21)[2]/45, XY,-22,-8,+ der(8)t(8;22)(q24.3;q11.21)[22]/45,XY,-22,-5,+ der(5)t(5;22)(q35.3;q11.21)[44]. A C-banding and FISH study with a specific centromeric probe (D14Z1/D22Z1) for chromosome 22 was made. In our case, partial monosomy for the regions 22q11.21-->22pter, 8q24.3-->8qter and 5q35.3-->5qter may partially explain the fetal malformations.     

Mosaic 46,XY,der(15)t(6;15)(q25.1;p12)/46,XY at amniocentesis in a pregnancy associated with a favorable fetal outcome and postnatal decrease of the aneuploid cell line with the unbalanced translocation

ObjectiveWe present mosaic 46,XY,der(15)t(6;15)(q25.1;p12)/46,XY at amniocentesis in a pregnancy associated with a favorable fetal outcome and postnatal decrease of the aneuploid cell line with the unbalanced translocation.Case reportA 34-year-old primigravid woman underwent amniocentesis at 17 weeks of gestation because of advanced maternal age. Amniocentesis revealed a karyotype of 46,XY,add(15)(p12)[17]/46,XY[5]. A second amniocentesis at 19 weeks of gestation revealed a karyotype of 46,XY,der(15)t(6;15)(q25.1;p12)[12]/46,XY[8], and array comparative genomic hybridization (aCGH) analysis on the DNA extracted from uncultured amniocytes revealed arr arr 6q25.1q27×2-3 with 40% mosaic level. She was referred for genetic counseling. Prenatal ultrasound and the parental karyotypes were normal. A third amniocentesis at 24 weeks of gestation revealed a karyotype of 46,XY,der(15)t(6;15)(q25.1;p12)[23]/46,XY[1], and in uncultured amniocytes, aCGH analysis revealed arr 6q25.1q27×2.5, interphase fluorescence in situ hybridization (FISH) revealed 51% mosaicism (51/100 cells) for partial trisomy 6q and quantitative fluorescence polymerase chain reaction (QF-PCR) analysis determined maternal origin of the aberrant chromosome and excluded uniparental disomy (UPD) 15 and UPD 6. A fourth amniocentesis at 27 weeks of gestation revealed a karyotype of 46,XY,der(15)t(6;15)(q25.1;p12)[21]/46,XY[5], and in uncultured amniocytes, aCGH analysis revealed arr 6q25.1q27×2.46, and interphase FISH revealed 35% mosaicism (35/100 cells) for partial trisomy 6q. At 39 weeks of gestation, a healthy 3028-g male baby was delivered without any phenotypic abnormality. The karyotypes of cord blood, umbilical cord and placenta were 46,XY,der(15)t(6;15)(q25.1;p12)[2]/46,XY,der(15)t(6;15)(q25.1;p12)[29]/46,XY[11] and 46,XY, respectively. When follow-up at age one month, the neonate was phenotypically normal, the peripheral blood had a karyotype of 46,XY (40/40 cells), and FISH analysis on 105 buccal mucosal cells detected five cells with partial trisomy 6q compared with 2% mosaicism (2/100 cells) in the normal control.ConclusionMosaicism for an unbalanced translocation with a normal cell line without UPD at amniocentesis can be a transient and benign condition, and can be associated with a favorable fetal outcome and postnatal decrease of the aneuploid cell line.     

Prenatal diagnosis and fetal pathology of partial trisomy 20P-monosomy 4P resulting from paternal translocation

Amniocentesis was performed in view of a paternal balanced chromosomal rearrangement t(4;20)(p16;p12), inv(18)(p11q11). The pregnancy was complicated by severe oligohydramnios. The fetal karyotype was unbalanced: 46XX, der(4), t(4;20)(p16;p12), inv(18) (p11q11)pat., thus resulting in partial trisomy 20p and monosomy 4p. In addition, the amniotic fluid alpha-fetoprotein (AFP) became increasingly elevated with gestational age. The pregnancy was terminated at 25 weeks. The fetus presented with typical facial dysmorphic features, unilateral cleft lip and palate, severe renal hypoplasia, consistent with the 4p-(Wolf-Hirschhorn) syndrome.     

Prenatal diagnosis and molecular cytogenetic analysis of partial monosomy 10q (10q25.3-->qter) and partial trisomy 18q (18q23-->qter) in a fetus associated with cystic hygroma and ambiguous genitalia

OBJECTIVES: To present the prenatal diagnosis and molecular cytogenetic analysis of a fetus with nuchal cystic hygroma and ambiguous genitalia. CASE AND METHODS: Amniocentesis was performed at 16 weeks' gestation because of the abnormal fetal sonographic finding of a large septated nuchal cystic hygroma. Genetic amniocentesis revealed a terminal deletion in the long arm of chromosome 10. The paternal karyotype was subsequently found to be 46,XY,t(10;18)(q25.3;q23). The maternal karyotype was normal. The pregnancy was terminated. A hydropic fetus was delivered with a septated nuchal cystic hygroma and ambiguous genitalia. Fluorescence in situ hybridization (FISH), microarray-based comparative genomic hybridization (CGH), and polymorphic DNA markers were used to investigate the involved chromosomal segments. RESULTS: FISH study showed absence of the 10q telomeric probe and presence of the 18q telomeric probe in the derivative chromosome 10. Microarray-based CGH analysis showed loss of distal 10q and gain of distal 18q. Polymorphic DNA marker analysis determined the breakpoints. The fetal karyotype was 46,XY,der(10)t(10;18)(q25.3;q23)pat. The chromosome aberration resulted in partial monosomy 10q (10q25.3-->qter) and partial trisomy 18q (18q23-->qter). CONCLUSIONS: The present case provides evidence that partial monosomy 10q (10q25.3-->qter) with partial trisomy 18q (18q23-->qter) can be a genetic cause of fetal cystic hygroma and ambiguous genitalia. Cytogenetic analysis for prenatally detected structural abnormalities may detect unexpected inherited chromosome aberrations.     

Molecular cytogenetic characterization of Jacobsen syndrome (11q23.3-q25 deletion) in a fetus associated with double outlet right ventricle,hypoplastic left heart syndrome and ductus venosus agenesis on prenatal ultrasound

Objective

We present molecular cytogenetic characterization of Jacobsen syndrome (11q23.3-q25 deletion) in a fetus associated with double outlet right ventricle (DORV), hypoplastic left heart syndrome (HLHS), and ductus venosus (DV) agenesis on prenatal ultrasound.

Microphthalmia with linear skin defects (MLS) syndrome evaluated by prenatal karyotyping, FISH and array comparative genomic hybridization

OBJECTIVE: To explore the utility of comparative genomic hybridization to BAC arrays (array CGH) for prenatal diagnosis of microphthalmia and linear skin defects syndrome. METHODS: We used karyotype analysis, FISH and array CGH to investigate an X;Y translocation. Replication studies were done on cultured amniocytes and lymphoblasts. RESULTS: We describe a severe case of MLS syndrome that presented prenatally with multiple anomalies including cystic hygroma, microphthalmia, intrauterine growth restriction and a complex congenital heart defect. Cytogenetic analysis of amniocytes revealed an unbalanced de novo translocation between chromosomes X and Y [karyotype 46,X,der(X)t(X;Y)(p22.3;q11.2).ish der(X)(DXZ1+,DMD+,KAL-,STS-,SRY-),22q11.2 (Tuple1 x 2)]. MLS diagnosis was made at birth and the prenatal karyotype was confirmed. Replication studies showed the derivative X chromosome was the inactive X. Array CGH confirmed the X and Y imbalances seen in the karyotype and also showed twelve BACs in the MLS region were deleted as a result of the translocation. FISH with BAC clones verified the array findings and placed the X breakpoint in Xp22.2, resulting in the amended karyotype, 46,X,der(X)t(X;Y)(p22.2;q11.2).ish der(X)(DXZ1+,DMD+,KAL-,STS-,SRY-),22q11.2(Tuple1 x 2) arr cgh Xp22.33p22.2(LLNOYCO3M15D10 -->GS1-590J6)x 1,Yq11.222q23(RP11-20H21-->RP11-79J10)x 1. CONCLUSION: The sensitivity of array CGH was valuable in detecting monosomy of the MLS critical region. Array CGH should be considered for the prenatal diagnosis of this syndrome.