The risk of spina bifida aperta after first-trimester exposure to valproate in a prenatal cohort.

Use of antiepileptic drugs (AEDs) during pregnancy is associated with an increased risk of congenital malformations. Spina bifida aperta has been linked specifically to valproic acid (VPA) (estimated risk, 1 to 2%). The actual risk, the exclusive association of VPA with spina bifida and not anencephaly, and the precise causative relation remain matters of discussion. A prospective cohort study of pregnant women with epilepsy receiving AEDs and referred for prenatal diagnosis before week 22 of gestation was conducted, with follow-up to 3 months after birth. Pregnancies (291 singleton and 6 twin) in 261 women were evaluated. The prevalence of anomalies after exposure to any AED was 6.9%. For fetuses exposed to VPA, the prevalence was 9.4%, including six cases of spina bifida, two of which were in monozygotic twins (giving a prevalence rate of 6.3%, or 5.4%, if twins counted as one). Spina bifida was associated with a significantly higher average daily dose of VPA as compared with pregnancies with normal outcome (1.640 +/- 136 mg/d vs 941 +/- 48 mg/d, p = 0.0001). No relation was observed between the occurrence of spina bifida and type of maternal seizure or epilepsy, family history of epilepsy or neural-tube defects, or medical history. From these results we suggest that when the use of VPA during pregnancy cannot be avoided, the teratogenic risk might be diminished by reduction of the daily dose.

Acceptance of chorionic villus sampling in the southwest region of The Netherlands: a 5-year evaluation.

The acceptance of chorionic villus sampling (CVS) for monitoring pregnancies at risk for chromosomal and genetic disorders was studied from its introduction in the Centre for Clinical Genetics in Rotterdam in 1984 until 1988. Special attention was given to increasing acceptance in the group with advanced maternal age (AMA) (12.6% CVS in 1984, 52.2% CVS in 1988) and the group with a high genetic risk (HGR) (42.7% in 1984, 86.7% in 1988). The odds-growth-rate in CVS was 1.64 and 1.67 respectively, which was not significantly different. The relatively limited use of CVS at AMA is most likely determined by the fact that a considerable number of patients are referred too late in pregnancy to have the option of CVS.

Case of 45,X/46,XY mosaicism with non-mosaic discordance between short-term villi (45,X) and cultured villi (46,XY).

We report on a prenatally detected case of discordant non-mosaic karyotypes following chorionic villus sampling. A 45,X karyotype was found in cytotrophoblast cells and a 46,XY karyotype in mesenchymal core cells. A subsequent amniocentesis showed a true 45,X/46,XY mosaicism. Confirmatory studies, including fluorescence in situ hybridization (FISH) in various fetal and placental tissues as well as in the original villi preparations changed the presumed condition of generalized mosaicism with culture confined normality to that of generalized mosaicism with absolute concordance. This case underscores the importance of the investigation of both short-term and cultured villi preparations, the implementation of prenatal FISH studies, and the need for thorough follow-up investigation in cases of discrepant results.

Prenatal detection of trisomy 18 caused by isochromosome 18p and 18q formation.

We report on the prenatal detection and further genetic studies in a case of trisomy 18 caused by isochromosome 18p [i(18p)] and 18q [i(18q)] formation. The diagnosis was made by standard cytogenetic techniques in amniotic fluid cells and confirmed by fluorescence in situ hybridization. The formation of the isochromosomes cannot be explained by a single model; centromere misdivision and meiosis II nondisjunction without recombination or mitotic misdivision are the most likely mechanisms of formation as indicated by DNA analysis.

Interpretation of chromosome mosaicism and discrepancies in chorionic villi studies.

In 3,000 chorionic villi studies (CVS) 33 cases of mosaicism and 7 false-positive cell lines in all cells were seen. The mosaic cell lines were caused by aneuploidy of autosomes (13x), sex chromosomes (9x), and structural anomalies (11x). Mosaics of fetal origin were only 4 cases of trisomy 21 and one 47,XXY mosaic. In 7 cases abnormal karyotype of non-fetal origin was seen in all cells in direct studies, including trisomy 16 (3x) and trisomy 18 (2x). The combined use of direct CVS and cell cultures always uncovered the non-fetal origin of chromosome abnormalities and the study of cultured cells in all cases could have prevented 5 terminations. Complete follow-up studies demonstrated no false-negative results. Therefore, CVS can be nearly 100% accurate when both direct studies and cultures are examined in cases of mosaicism and other cell lines of possible non-fetal origin, such as trisomy 16, trisomy 18, translocation (21;21), and 45,X cells.

Terminal transverse limb defects and early chorionic villus sampling: evaluation of 4,300 cases with completed follow-up.

Data from 4,300 consecutive cases following prenatal diagnosis by transcervical (TC) CVS (n = 1,570) and transabdominal (TA) CVS (n = 2,370) were evaluated. In the follow-up study only infants examined by a physician were included. Gestational age varied between 8.5 and 11.6 weeks (mean 10.3 weeks) for TC-CVS and between 9.3 and 20 weeks (mean 12.3 weeks) for TA-CVS 98% of TC-CVS was performed at 9-10 weeks, 80.7% of TA-CVS procedures were carried out at 12-15 weeks. Selective termination took place in 97 cases of TC-CVS (6.1%) and in 72 cases of TA-CVS (2.6%). Another 8 women had a termination for psychosocial reasons, resulting in 4,123 (1,469 TC, 2,654 TA) continuing pregnancies. The overall fetal loss rate < 28 weeks was 5.4% (n = 80) for TC-CVS and 2.6% (n = 70) for TA-CVS. The overall incidence of congenital abnormalities after birth was 0.9%. Two terminal transversal limb defects were detected in the TC-CVS group (0.14%) against one (0.04%) in the TA-CVS group.

Prenatal diagnosis of cystic kidney disease with ventriculomegaly: a report of six cases in two related sibships.

In 2 consanguineous relationships, a Cape Verdian man fathered six fetuses (5 male) with fetal ventriculomegaly and echodense fetal kidneys as visualized by ultrasonography between 16 and 32 weeks. During prenatal monitoring, an increased alpha fetoprotein level and abnormal acetylcholinesterase were detected at amniocentesis in 5 of 6 affected fetuses. Chromosomes were normal. Five pregnancies resulted in elective termination; one child was still-born prematurely. Hydrocephalus and cystic disease of the (renal) cortico medullary areas were found. One fetus had polydactyly. The differential diagnosis and prenatal diagnosis of this presumably autosomal recessive syndrome are discussed.

Ring chromosome 18 in a fetus with only facial anomalies.

We report on a prenatally detected case of ring chromosome 18 [46,XX,r(18)] in amniotic fluid cells of a fetus with an abnormal facial profile on ultrasound as the only malformation. The chromosome 18 origin of the ring chromosome, of a supernumerary marker chromosome in some cells, and of micronuclei was demonstrated by fluorescent in situ hybridization with a whole chromosome 18 paint (Cambio) and 18 centromere probe L1.84. DNA investigations showed deletions of 18p as well as 18q material of r(18), which turned out to be of paternal origin. Autopsy of the fetus after termination of pregnancy at 20 weeks of gestation showed no additional malformations, in agreement with the previous ultrasound findings.

Transabdominal chorionic villus sampling in a multiple pregnancy at risk of argininosuccinic aciduria: a case report.

We report on a 32-year-old G3P2 woman at increased risk of argininosuccinic aciduria in her offspring. In her first infant, the disease was diagnosed at age 3 months. In the second pregnancy, the disorder was excluded following incorporation of radio-labeled 14C-citrulline in intact chorionic villi obtained through transcervical chorionic villus sampling at 10 weeks gestation. Twins were diagnosed in the third pregnancy. Separate transabdominal chorionic villus sampling of both fetuses was carried out at 10 weeks gestation. Chromosome analysis demonstrated a normal male and female karyotype. Incorporation of radio-labeled 14C-citrulline in intact villi was deficient in both villus samples, establishing the diagnosis of argininosuccinic aciduria in both fetuses. The present results confirm the reliability of direct analysis of villi for the diagnosis of argininosuccinic aciduria.

Prenatal diagnosis of Niemann-Pick disease type C.

Niemann-Pick disease type C (NPC) was demonstrated in two successive pregnancies by strongly reduced activity of sphingomyelinase in amniotic fluid cells. By contrast, chorionic villi from the first pregnancy had shown normal sphingomyelinase activity. The prenatal diagnosis of NPC in the two fetuses was confirmed, after termination of the pregnancies, by (phospho)lipid analyses of the fetal livers, by the assay of sphingomyelinase in the fetal fibroblasts and by the demonstration of a defective esterification of exogenous cholesterol and of cholesterol accumulation by filipin staining. Retrospective analysis of cultured amniocytes for cholesterol esterification and filipin staining confirmed the feasibility of these methods for prenatal diagnosis. In a recent pregnancy in the same mother the three available methods were applied to amniotic fluid cells and an unaffected child was correctly predicted. Lipid analysis of liver tissue from the patient with NPC and the two fetuses showed a 3-5 times increased level of cholesterol, a 2-3 times increased level of sphingomyelin and a remarkable increase of bis (monoacylglyceryl) phosphate.

Prenatal diagnosis of ataxia-telangiectasia and Nijmegen Breakage syndrome by the assay of radioresistant DNA synthesis.

Prenatal diagnosis was performed in 16 pregnancies at risk of ataxia-telangiectasia (A-T) or Nijmegen Breakage Syndrome (NBS). Radioresistant DNA synthesis (RDS) was investigated in cultured chorionic villus (CV) cells and/or amniotic fluid (AF) cells. In four pregnancies, an affected foetus was diagnosed with increased RDS in cultured CV cells. In three of the four cases confirmation of the diagnosis was obtained by analysis of AF cells and/or skin fibroblasts from the foetus cultured after termination of the pregnancy; in the fourth case a fibroblast culture from the aborted foetus failed. In one case, only AF cells could be analysed in a late stage of pregnancy; pregnancy was terminated due to intermediate/equivocal results but the foetal fibroblasts showed normal RDS. Normal RDS was demonstrated in the other 11 pregnancies at 25% risk either by analysis of CV cells (nine cases) or of AF cells (two cases). In some cases the (normal) results on the CV cells were corroborated by subsequent analysis of AF cells. The results suggest that RDS analysis of CV cells allows reliable prenatal diagnosis of A-T/NBS. However, amniocentesis may be necessary to confirm normal results on CV cells if the foetus is female (because of the risk of maternal cell contamination) or in the rare case of equivocal results.

Chromosome analysis of small and large L5178Y mouse lymphoma cell colonies: comparison of trifluorothymidine-resistant and unselected cell colonies from mutagen-treated and control cultures.

Mutagenesis assays at the thymidine kinase (TK) locus in L5178Y mouse lymphoma cells frequently yield mutant colonies with a bimodal size distribution. The objectives of this study were to determine whether a relationship exists between mutant colony size and chromosomal aberrations and whether the colony-size distributions obtained from this assay can indicate the clastogenic activity of a test chemical. Cells from 8 different types of L5178Y mouse lymphoma cell colonies were examined for chromosomal abnormalities within 10 cell generations after colony isolation. The colonies included small (sigma) and large (lambda) unselected cell (UC) and trifluorothymidine-resistant (TFTr) colonies derived from TK +/- cell cultures treated with the solvent dimethyl sulfoxide (DMSO) or hycanthone methanesulfonate (HYC). Chromosome abnormalities were present in cells from 12% (7/60) of the UC colonies, but there was no apparent relationship between colony diameter and the presence of chromosomal abnormalities. Abnormalities affecting chromosome 11, which is believed to be the site of the TK gene, were not observed in cells from UC colonies. Abnormalities affecting chromosome 11 were observed only in cells from sigma-TFTr colonies irrespective of whether they were spontaneous (5/15 colonies) or induced by HYC (4/15 colonies). Overall, 30% (9/30) of sigma-TFTr colonies had cells with an abnormal chromosome 11 and 10% (3/30) had abnormalities affecting other chromosomes. Abnormalities affecting chromosome 11 were not observed in cells from lambda-TFTr colonies (0/30 colonies). The observation of only 30% of sigma-TFTr colonies with chromosome damage affecting chromosome 11 indicates that other mechanisms, in addition to chromosome damage at the level of resolution used in this study (i.e., 200-300 chromosome bands). contribute to small TFTr colony size.

[Twenty years of experience in advanced ultrasound scanning for fetal anomalies in Rotterdam]. / Geavanceerd ultrageluidonderzoek naar aangeboren afwijkingen in Rotterdam; 20 jaar ervaring.

At the Rotterdam Fetal Medicine Unit over a period of 20 years, scanning for foetal anomalies has been performed in more than 24,000 pregnancies at risk of a foetal congenital anomaly. In pregnancies where there was prior knowledge of increased risk of a foetal anomaly (group I), the incidence of foetal pathology was 2-5%. In pregnancies in which a foetal anomaly was suspected on clinical or sonographic grounds (group II), the incidence of foetal pathology was 32-57%. For reasons of good-image quality, group I pregnancies were nearly always referred for a foetal-anomaly scan at 18-21 weeks of gestation. Group II pregnancies were often referred after 24 weeks of gestation, which is the upper legal limit for termination of pregnancy in the Netherlands. The detection rate was 94.7% (2000 and 2001). An abnormal chromosome pattern was established in 18% of all affected pregnancies, the great majority of these patterns (83%) being numerical. Approximately 18% of affected pregnancies were discussed in a multidisciplinary setting to ensure correct diagnosis, prognosis and management. Depending on the nature and severity of the foetal anomaly, standard obstetric management was advised in two thirds of cases. In the remaining one third termination of pregnancy was carried out at the request of the parents or a policy of obstetric non-intervention was adopted. In a subgroup comprising 460 pregnant women with both indications for referral, who were investigated at 12-14 weeks gestation, the detection rate for a number of congenital abnormalities was 89.5%.

Transmission and prenatal diagnosis of the T9176C mitochondrial DNA mutation.

A family presented with three affected children with Leigh syndrome, a progressive neurodegenerative disorder. Analysis of the OXPHOS complexes in muscle of two affected patients showed an increase in activity of pyruvate dehydrogenase and a decrease of complex V activity. Mutation analysis revealed the T9176C mutation in the mtATPase 6 gene (OMIM 516060) and the mutation load was above 90% in the patients. Unaffected maternal relatives were tested for carrier-ship and one of them, with a mutation load of 55% in blood, was pregnant with her first child. The possibility of prenatal diagnosis was evaluated. The main problem was the lack of data on genotype-phenotype associations for the T9176C mutation and on variation of the mutation percentage in tissues and in time. Therefore, multiple tissues of affected and unaffected carriers were analysed. Eventually, prenatal diagnosis was offered with understanding by the couple that there could be considerable uncertainty in the interpretation of the results. Prenatal diagnosis was carried out twice on cultured and uncultured chorion villi and amniotic fluid cells. The result was a mutation percentage just below the assumed threshold of expression (90%). The couple decided to continue the pregnancy and an apparently healthy child was born with an as yet unclear prognosis. This is the first prenatal diagnosis for a carrier of the T9176C mutation. Prenatal diagnosis for this mutation is technically reliable, but the prognostic predictions are not straightforward.

A case of early intrauterine parvovirus B19 infection.

We present a case of parvovirus B19 infection in the first trimester, confirmed by polymerase chain reaction (PCR) in amniotic fluid and cord blood, that caused myocarditis, severe intrauterine growth retardation, and probably glomerulonephritis. Eventually a small-for-dates neonate was born, without any signs of the infection.

Clinical significance of placenta-confined nonmosaic trisomy 16.

Since the introduction of chorionic villi sampling in 1984 we have observed five first-trimester cases of nonmosaic placenta confined trisomy 16. At subsequent follow-up it appeared that all five had an adverse maternal or fetal outcome. In three cases the mother had preeclampsia. Two of the infants were born with multiple congenital abnormalities, including tetralogy of Fallot. All children were growth retarded.

Prenatal diagnosis of congenital cystic adenomatoid lung malformation: a report of seven cases.

Six cases of macrocystic and one case of microcystic congenital adenomatoid lung malformation were diagnosed by ultrasound between 20 and 31 weeks of gestation. Combined polyhydramnios and fetal hydrops was present in three cases, polyhydramnios alone in one case, and isolated fetal hydrops also in one case. In the remaining two cases, both polyhydramnios and fetal hydrops were absent. Fetal outcome was poor, i.e., two terminations of pregnancy, three early neonatal deaths, and two survivors.