1/255. 'Identical' twins with discordant karyotypes.A chromosomal abnormality in one of the fetuses of a monozygotic twin pregnancy is a rare phenomenon. In the prenatal unit of our cytogenetics laboratory we have recently come across two such heterokaryotypic twin pregnancies. In both cases ultrasound abnormalities were detected in one fetus of each twin pair. Chromosomal analysis showed that one twin pregnancy was discordant for trisomy 21 and the other for 45,X. Ultrasonographic examination suggested a monochorionic twin pregnancy in each case and dna studies confirmed that both sets of twins were monozygotic. Both pregnancies were terminated. Biopsies taken from different sites of the placentas showed chromosomal mosaicism in both cases. There was no clear correlation between the karyotype found close to the site of the umbilical cord insertion in the placenta and the karyotype of the fetus. Sampling of amniotic fluid from both sacs is recommended in diamniotic twin pregnancies if one (or both) of the fetuses has ultrasound abnormalities, even if the twins are apparently monochorionic.- - - - - - - - - - ranking = 1keywords = pregnancy (Clic here for more details about this article) |
2/255. trisomy/tetrasomy 21 mosaicism in CVS: interpretation of cytogenetic discrepancies between placental and fetal chromosome complements.trisomy/tetrasomy 21 mosaicism was found in chorionic villi (semidirect preparation) obtained from a 40 year old pregnant woman. Since both cell lines were abnormal, the couple elected for pregnancy termination. placenta and fetal tissue samples were obtained for cytogenetic study. Long term cultured villi showed a non-mosaic trisomy 21 karyotype, while other tissues showed either a normal karyotype or normal/trisomy21 mosaicism. These discrepancies could be explained by a modified "bottle neck" embryogenic model with a trisomic zygote and a non-disjunction event taking place in one of the first divisions. Our case emphasises the need for confirmatory studies in other tissues when mosaicism is encountered in chorionic villi, even if all cell lines are abnormal.- - - - - - - - - - ranking = 0.33333333333333keywords = pregnancy (Clic here for more details about this article) |
3/255. Clinical details, cytogenic studies,and cellular physiology of a 69, XXX fetus, with comments on the biological effect of triploidy in man.A triploid fetus, 69, XXX, aborted spontaneously at 26 weeks' gestation. It had multiple abnormalities including syndactyly of the hands and feet single palmar creases, hypoplasia of the adrenals and ovaries, hypertrophy of thigh muscles, and abnormalities of the brain. The placenta was large and showed hydatidiform degeneration. The pregnancy had been complicated by acute dyspnoea, pre-eclampsia, and postpartum haemorrhage. Detailed cytogenetic studies, using banding and fluorescence techniques, were performed on fetus and parents. Meiotic studies were made on the fetal ovaries. Muscle cell differentiation and electrophysiological relationships of cultured skin fibriblasts were examined in an attempt to study the way in which the extra haploid set of chromosomes exerts its effect on the phenotype. The antenatal diagnosis of late triploidy is discussed. The finding that 25 per cent of late triploids have spina bifida is further evidence that meningomyelocele has a genetic component and strongly suggests that this results from chromosomal imbalance or a regulatory gene disturbance.- - - - - - - - - - ranking = 0.96134776478171keywords = gestation, pregnancy (Clic here for more details about this article) |
4/255. prenatal diagnosis of a mosaic extra structurally abnormal chromosome by spectral karyotyping.A de novo mosaic extra structurally abnormal chromosome (ESAC) was detected in 33 per cent of cultured amniotic fluid cells from a pregnant woman. Neither Q-banding nor fluorescence in situ hybridization (FISH) employing a dna probe for nucleolar organizer region demonstrated the presence of satellites on the ESAC. spectral karyotyping (SKY) was performed in this prenatal case and led to a quick and accurate determination of the ESAC as chromosome 14 in origin. The SKY finding was confirmed by conventional FISH analysis using a chromosome 14 specific painting probe. Subsequent hybridizations with a centromeric probe and a 14q subtelomeric probe were also performed to further characterize the ESAC. Absence of (TTAGGG)n sequence on the ESAC, determined postnatally, suggested it is a ring chromosome 14. Genetic counselling concerning these findings was provided to the parents who chose to continue the pregnancy. The male infant had no apparent abnormal phenotype at birth.- - - - - - - - - - ranking = 0.33333333333333keywords = pregnancy (Clic here for more details about this article) |
5/255. prenatal diagnosis in a family with severe type I plasminogen deficiency, ligneous conjunctivitis and congenital hydrocephalus.Severe type I plasminogen deficiency may cause severe ligneous conjunctivitis, a rare and unusual form of chronic pseudo-membranous conjunctivitis that usually starts in early infancy, but also pseudo-membranous lesions of other mucous membranes in the mouth, nasopharynx, trachea and female genital tract, and in rare cases congenital occlusive hydrocephalus. The index patient, the daughter of a consanguineous marriage, had suffered from severe ligneous conjunctivitis and had died from decompensated congenital hydrocephalus despite numerous shunt revisions. She was found to be homozygous for a non-sense mutation in exon 15 of the plasminogen gene (Trp597->Stop). In her next pregnancy, the mother asked for prenatal diagnosis of the plasminogen deficiency. Chorionic villus biopsy was performed at 12 weeks of gestation. dna analysis of the plasminogen gene by PCR and single-strand conformation polymorphism (SSCP) revealed that the fetus exhibited an identical heterozygous band pattern as observed in the healthy mother. Therefore, the fetus was heterozygous for the Trp597->Stop mutation in plasminogen exon 15. In addition, the fetus was found to be male by cytogenetic analysis and by multiplex PCR analysis using two polymorphic X-chromosomal markers (DXS424, HPRT). These findings excluded the possibility of contamination by maternal dna. It was concluded that the fetus was not at risk for ligneous conjunctivitis and its associated complications. After the birth of a healthy boy, plasminogen functional activity was shown to be 38 per cent. dna analysis confirmed prenatal molecular genetic results.- - - - - - - - - - ranking = 0.96134776478171keywords = gestation, pregnancy (Clic here for more details about this article) |
6/255. Partial trisomy 13q22-->qter and monosomy 18q21-->qter as a result of familial translocation.We report on a patient with a partial trisomy of chromosome 13q22-->qter and partial monosomy of chromosome 18q21-->qter showing distinct malformations. The phenotype of this unbalanced karyotype has not been previously described. The proband had a craniofacial dysmorphism, neck pterygium, closed fists with overlapping fingers, cutaneous appendix of the left fist, equinovarus and postaxial hexadactyly of the feet, atrial septum defect, unilateral cryptorchidism and hypertrophic pyloric stenosis. Using fluorescence in situ hybridization (FISH) the father's karyotype 46,XY.ish t(13;18)(13pter-->13q22::18q21-->18qter; 18pter-->18q21::13q22-->13qter) and the child's 46,XY.ish der(18)(18pter-->18q21::13q22-->13qter)pat were established. The mother's karyotype was normal. A risk of unbalanced offspring in carriers of a balanced reciprocal translocation depends on the length and genetic constitution of the exchanged segments. risk figures should come only from empirical data. A phenotypically normal child with a balanced or normal karyotype could be born in the case of alternate segregation. amniocentesis should therefore be recommended in any further pregnancy.- - - - - - - - - - ranking = 0.33333333333333keywords = pregnancy (Clic here for more details about this article) |
7/255. Maternal uniparental isodisomy for chromosome 14 detected prenatally.Maternal uniparental disomy (UPD) for chromosome 14 (upd(14)mat) has been associated with a distinct phenotype. We describe the first case of maternal uniparental isodisomy for chromosome 14 detected prenatally, in a pregnancy with mosaicism for trisomy 14 observed in both a chorionic villus sample (CVS) and in amniocytes. Detailed analysis of polymorphic microsatellites showed that the fetus was essentially isodisomic for one of the mother's chromosomes 14 and that recombination had introduced a mid-long arm region of heterodisomy. The fetus, which died in utero at 18 weeks, showed no apparent pathological features. The case demonstrates for the first time a maternal meiosis II non-disjunction of chromosome 14 leading to a trisomic conception which has been incompletely corrected by 'rescue' in the early embryo.- - - - - - - - - - ranking = 0.33333333333333keywords = pregnancy (Clic here for more details about this article) |
8/255. 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.- - - - - - - - - - ranking = 0.96134776478171keywords = gestation, pregnancy (Clic here for more details about this article) |
9/255. Maternal uniparental disomy for chromosome 14 in a boy with a normal karyotype.We report on a boy with a maternal uniparental disomy for chromosome 14 (UPD(14)). At 7 years of age he was referred to us by the paediatrician because of symptoms of prader-willi syndrome (PWS). He showed short stature, obesity, mild developmental delay, cryptorchidism, and some mild dysmorphic features. The history further indicated intrauterine growth retardation at the end of the pregnancy. His mother was 44 years of age at the time of his birth. After birth he showed hypotonia with poor sucking, for which gavage feeding was needed. Motor development was delayed. After 1 year he became obese despite a normal appetite. Recurrent middle ear infections, a high pain threshold, and a great skill with jigsaw puzzles were reported. There were no behavioural problems or sleep disturbance. Chromosomal analysis was normal (46,XY). dna analysis for prader-willi syndrome showed no abnormalities. Two years later he was re-examined because we thought his features fitted the PWS-like phenotype associated with maternal UPD(14). At that time precocious puberty was evident. dna analysis showed maternal heterodisomy for chromosome 14. In all the previously described 11 cases with maternal UPD(14), a Robertsonian translocation involving chromosome 14 was detected cytogenetically before dna analysis. This is the first report of diagnosis of maternal UPD(14) based on clinical features. This finding underlines the importance of dna analysis for maternal UPD(14) in patients with a similar PWS-like phenotype even without previous identification of a Robertsonian translocation involving chromosome 14.- - - - - - - - - - ranking = 0.33333333333333keywords = pregnancy (Clic here for more details about this article) |
10/255. Analysis of a de novo complex chromosome rearrangement involving chromosomes 4, 11, 12 and 13 and eight breakpoints by conventional cytogenetic, fluorescence in situ hybridization and spectral karyotyping.A complex chromosome rearrangement (CCR) with eight breakpoints resulting in four derivative chromosomes (4, 11, 12 and 13) was detected prenatally in a male fetus of a twin pregnancy. The karyotype of the female second fetus was normal. The apparently balanced de novo CCR was identified by classical cytogenetic methods and fluorescence in situ hybridization (FISH). We compared these findings with results from spectral karyotyping (SKY).- - - - - - - - - - ranking = 0.33333333333333keywords = pregnancy (Clic here for more details about this article) |
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