Trisomy 5 mosaicism detected prenatally with an affected liveborn

This paper reports a case of chromosomal mosaicism for trisomy 5 recovered from amniotic fluid cells and from skin fibroblasts of a liveborn dysmorphic male. Routine amniocentesis was performed at 16 weeks' gestation because of parental concern. Trisomy 5 cells were measured from 25 per cent of amniocytes from two culture vessels. No further invasive testing was performed until 32 weeks' gestation, at which time ultrasound examination showed fetus with intrauterine growth retardation. Fetal blood sampling was then performed, with only karyotypically normal cells recovered. At birth, the child was found to have multiple dysmorphic features and congenital anomalies, including an eventration of the diaphragm and ventricular septal defect, both of which required surgical correction. Chromosomal analysis of cord blood lymphocytes indicated 46,XY; however, 20 per cent of the cultured fibroblasts obtained from the chest skin at the incision site for diaphragmatic repair had a 47,XY,+5 karyotype. Trisomy 5 mosaicism may be another example of tissue-limited mosaicism. Fetal blood sampling can then be falsely reassuring. Furthermore, because some cell lines rarely appear in lymphocyte populations, cytogenetic analysis of multiple tissues warranted as part of the evaluation of individuals with developmental delay and dysmorphic features.     

Prenatal detection of trisomy 9 mosaicism

Chromosomal mosaicism in amniotic fluid cells poses a serious dilemma in prenatal diagnosis since the observation may represent: (1) pseudomosaicism—an inconsequential tissue culture artefact; or (2) true mosaicism—occurring in approximately 0.0 per cent of amniocenteses with a significant impact on pregnancy outcome. Mosaicism for trisomy 9 was observed in an amniotic fluid specimen obtained for advanced maternal age with two cell lines [46,XX (46 per cent)/47,XX, + 9 (54 per cent)] present in each of four culture flasks. Since more than 75 per cent of newborns with trisomy 9 mosaicism have complex cardiac malformations, a fetal echocardiogram was obtained at 20 weeks' gestation and interpreted as normal. A fetal blood sample (22 weeks' gestation) disclosed only a single trisomy 9 cell among the 100 metaphases analysed. However, a second fetal echocardiogram performed at the time of blood sampling suggested a non-specific cardiac anomaly. Fetal autopsy following elective pregnancy termination revealed several malformations including severe micrognathia, persistence of the left superior vena cava, and skeletal anomalies. Cytogenetic studies of cell cultures derived from several fetal tissues demonstrated trisomy 9 ranging from 12 to 24 per cent.     

An infant with trisomy 9 mosaicism presenting as a complete trisomy 9 by amniocentesis

We present a case in which amniocentesis performed at 33 weeks' gestation because of symmetrical intrauterine growth retardation and decreased amniotic fluid volume led to the prenatal diagnosis of a fetus with a karyotype of 47,XX,+9, t(1;20)(q42;p11.2) pat, i.e., with an extra chromosome 9 and a balanced translocation between chromosomes 1 and 20. At delivery, the baby showed clinical features of trisomy 9, yet chromosome analysis of the cord blood revealed no trisomy 9 cells, a finding confirmed by neonatal blood karyotyping. The balanced translocation was present in all cells. A skin biopsy confirmed trisomy 9 mosaicism with 10 per cent trisomy 9 cells. The baby died at 6 weeks and an autopsy was obtained. Chromosome analysis of different organs demonstrated different frequencies of the mosaicism of trisomy 9. The possible underlying mechanism for the discrepancy between the karyotype results by amniocentesis and those of other tissues is discussed.     

Visualization of fetal intra-abdominal organs in second-trimester severe oligohydramnios by intraperitoneal infusion

Fetal intraperitoneal infusion of saline was performed in two patients with severe oligohydramnios at 24 and 25 weeks' gestation in order to enhance visualization of intra-abdominal organs. Renal agenesis was easily diagnosed. The technique can be considered as an alternative to artificial instillation of amniotic fluid in the differential diagnosis of conditions associated with severe oligohydramnios.     

Prenatal detection of monosomy 21 mosaicism

We report a case of chromosomal mosaicism for monosomy 21 revealed in amniotic fluid cell culture. Ultrasound examination at 19 weeks' gestation showed in utero growth retardation and a complex cardiac malformation. A repeated amniocentesis confirmed the presence of monosomy 21 mosaicism. In view of the sonographically detected fetal abnormalities, termination of pregnancy was elected.     

True trisomy 15 mosaicism,detected by amniocentesis at 12 weeks of gestation and fetal echocardiography

A case of mosaicism of trisomy 15, with two-thirds of the cells trisomic, was detected at 12 weeks of gestation in amniotic fluid cell cultures obtained with the filtration technique. Ultrasound examination at 13 weeks showed a nodule protruding into the amniotic cavity which was speculated to be remnants of a co-twin, causing the trisomic cell line. At 20 weeks of gestation, a malformation scan (level III) was normal, but supplementary fetal echocardiography revealed a severe cardiac defect (mitral atresia and a ventricular septal defect). Fetal lymphocytes obtained by cordocentesis showed trisomy 15 mosaicism, but only in 5 per cent of the mitoses. After termination, the same percentage of trisomy 15 mosaicism was found in cells from skin and tendon as in the original early amniocentesis. No sign of earlier twinning was found in the placenta or membranes. We conclude that mosaicism in early amniotic fluid obtained by the filter technique in this case reflected the true karyotype accurately and that supplementary echocardiography added significantly to the interpretation of the clinical implications.     

SPONTANEOUS RESOLUTION OF CYSTIC HYGROMA IN A 46,XX NORMAL FEMALE

We report a case of nuchal cystic hygroma with spontaneous resolution detected by ultrasound examination at 13 weeks' gestation. Fetal karyotype and amniotic fluid alphafetoprotein levels were normal. Extreme caution in evaluating this situation is stressed.     

Prenatal diagnosis and post-mortem study of a fetus with mosaic trisomy 14 due to a dic(14)(p11)

Amniocentesis at 17 weeks' gestation revealed a mosaic karyotype—46,XX/46,XX, — 14,+dic(14)(p11). No abnormalities were detected on ultrasound. Growth and placentation were normal. The fetus was examined after termination of pregnancy and micrognathia and pulmonary hyperlobation were the only abnormalities detected. Several tissues were set up for cytogenetics, including fetal skin, kidney, ovary, and placenta. The diagnosis was confirmed by these studies. The level of mosaicism varied between tissues, with the trisomy 14 cell line highest in amniotic fluid.     

Prenatal diagnosis of pelvic kidney

A 30-year-old woman had serial ultrasound scans from 28 weeks' gestation which revealed the presence of a cystic area in the fetal pelvis. The ‘cyst’ remained unchanged until delivery at 41 weeks. Fetal growth and amniotic fluid volume were normal throughout. A pelvic kidney was confirmed at birth. The differential diagnosis and antenatal management of this ‘cyst’ are discussed.     

Prenatal diagnosis of trisomy 9 mosaicism possibly limited to fetal membranes

In repeat amniotic fluid cultures mosaicism due to trisomy 9 was noted. Autopsy of the aborted female fetus showed a sinus urogenitalis and gonadal dysgenesis with absence of germ cells only. Fetal lymphocytes and skin fibroblasts had a normal karyotype but trisomy 9 was found in cells grown from placenta. It is likely that trisomic cells were limited to fetal membranes.     

Fetal tissue involvement in the late infantile type of neuronal ceroid lipofuscinosis

Prenatal diagnosis in a pregnancy at risk for late infantile neuronal ceroid lipofuscinosis (Batten's disease) was undertaken at 17 weeks' gestation by ultrastructural examination of amniotic fluid cells. The presence of curvilinear profiles indicated an affected fetus and the diagnosis was confirmed, after the pregnancy was terminated, by the finding of many typical curvilinear profiles in multiple tissues which included skin, amnion, umbilical vessels, blood, liver, and brain. Comparison between the involved cells in the amniotic fluid and fetal tissues suggests that these cells are probably derived from the periderm, and possibly also from the amnion. The prominent presence of cytosomes in the periderm and intermediate cells of the fetal epidermis and occasionally also in the endothelial cells of the dermis suggests that fetal skin may be a useful alternative site for assessing fetal involvement. Control specimens of the amniotic fluid, fetal skin, amnion, and liver showed no similar cytosomes. However, some control amniotic fluid samples did contain cells with large collections of irregular trilaminar membranes, and these could be open to misinterpretation. It is important that only typical curvilinear profiles are considered as an indication of an affected pregnancy.     

First-trimester diagnosis of duodenal stenosis associated with oesophageal atresia

Duodenal stenosis associated with oesophageal atresia was diagnosed by ultrasound at 12 weeks' gestation. The diagnosis was made by recognition of a double bubble sign which was more pronounced when a vaginal transducer was used. Post-abortion autopsy confirmed the diagnosis. Oesophageal and duodenal obstruction in this case had no effect on the amount of amniotic fluid or the alpha-fetoprotein concentration since swallowing and subsequent utilization of amniotic fluid do not occur before 12 weeks of gestation.     

Oligohydramnios sequence in a live-born infant following chorionic villus sampling

We describe an infant born at 29 weeks' gestation with oligohydramnios sequence due to amniotic fluid leakage following chorionic villus sampling at 12 weeks. To our knowledge, this is the first such report.     

Oligohydramnios with amnio-chorionic separation at 15–16 weeks' gestation

Nine patients with oligohydramnios and amnio-chorionic separation were identified out of 7000 women who underwent a vaginal ultrasound examination at 15–16 weeks' gestation. Oligohydramnios was defined as a reduced amount of amniotic fluid, a distance of more than 1 cm between the chorion and amnion, and a good turgor of the amnion without floating membranes or intrauterine sheets. Fetal malformations were observed in all nine cases. In four of six fetuses where chromosomal analysis was available, an abnormal karyotype was found. It is concluded that oligohydramnios in the early second trimester is associated with fetal abnormality.     

Extraction of DNA from amniotic fluid cells for the early prenatal diagnosis of genetic disease

Ten-ml samples of amniotic fluid were taken from pregnancies being terminated at 8–14 weeks' gestation. DNA was extracted from the amniotic cells by sequential centrifugation and analysed using the polymerase chain reaction (PCR). Fifteen samples were analysed for evidence of maternal contamination using Mfd5 oligo-nucleotide primers for repeat polymorphisms. Ten amniotic fluid samples were tested for the Delta-F₅₀₈ deletion characteristic of cystic fibrosis to demonstrate a diagnostic application for the technique. In each case, DNA extracted from fetal tissue from the same pregnancy was included in the controls. In 14 of the 15 cases tested with the Mfd5 primers, both the amniotic fluid DNA and the fetal DNA showed no evidence of contaminating DNA. In one case, neither the amniotic fluid cells nor the fetal cells yielded results. In nine of the ten cases tested with the Delta-F₅₀₈ primers, the amniotic fluid cell DNA provided accurate information about the genetic status of the fetus; in the tenth, the fetal DNA failed to amplify. The results indicate that adequate DNA can be extracted from amniotic fluid from 8 weeks' gestation onward and these samples are suitable for prenatal diagnosis using PCR.     

Prenatal exclusion of homocystinuria (cystathionine β-synthase deficiency) by assay of phytohaemagglutinin-stimulated fetal lymphocytes

Homocystinuria due to cystathionine β-synthase deficiency was excluded in a fetus at 23 weeks' gestation by demonstrating activity of the enzyme in fetal lymphocytes after stimulation by phytohaemagglutinin. Fetal blood sampling was carried out because two determinations of enzyme activity on cultured amniotic cells gave low, not fully diagnostic values.     

Early amniocentesis at 11–14 weeks' gestation for the diagnosis of fetal chromosomal abnormality—a clinical evaluation

Early arnniocentesis between 11 and 14 weeks' gestation was offered to 110 women at risk of a chromosomally abnormal fetus due to maternal age. Four were found to be unsuitable for the procedure, and 106 early amniocenteses were performed. In 102 cases, clear amniotic fluid was obtained with a single tap. There were two dry taps and two bloodstained tapis; sampling was repeated in three of these cases before 15 weeks. In the fourth case, placental biopsy was performed at 16 weeks. Thus, we were able to obtain a satisfactory sample in all but three cases(2.8 percent). Karyotyping of cells harvested from the early amniotic fluid samples was successful in all the 105 cases. Cell culture from the initial samples revealed a normal karyotype in 99 cases, two balanced translocations, two tetraploid karyotypes, and two cases of pseudomosaicism. Of the 105 pregnancies successfully sampled, there have been two losses to date (1–8 per cent). Two further patients presented with premature rupture of membranes, both pregnancies having successful outcomes. Sixty-two babies have delivered to date, with four congenital anomalies. There were no respiratory problems. Twenty-nine pregnancies are continuing without known complications, and details are not yet available on the remaining 12. The results indicate that early arnniocentesis may replace the traditional test at 15–17 weeks.     

Prenatal diagnosis of congenital cytomegalovirus infection: False-negative amniocentesis at 20 weeks' gestation

Cytomegalovirus (CMV) is the most common cause of congenital infection. Recent studies show amniocentesis to be a 100 per cent sensitive and 100 per cent specific predictor of congenital infection, and recommend that it be offered in the at-risk pregnancy. However, these publications have focused on pregnancies at or beyond 22 weeks' gestation. Here, we report a case of maternal CMV hepatitis at 7–8 weeks' gestation, in which culture and polymerase chain reaction testing for CMV in amniotic fluid at 20 weeks' gestation were negative, but the infant had a positive CMV urine culture shortly after delivery. Implications for the prenatal diagnosis of CMV infection are discussed.     

Chorion biopsy in early pregnancy: A method of early prenatal diagnosis for inherited disorders

Chorion biopsy was performed in 165 cases at 6–12 weeks of pregnancy, following an ultrasonic or embryo-fetoscopic chorion frondosum localization. One hundred patients had their biopsies taken immediately before induced abortion. In 39 cases abortion was carried out 5–10 days after biopsy. In 26 pregnant patients biopsy was performed for genetic reasons. Fetal sex was determined in ‘native’ smears from biopsy specimens for cytological investigation, using X- and Y-chromatin assays. Fetal sex diagnosis proved correct in all the cases. In 40 observations, the origin of the biopsy specimen was histologically checked. In 16 biopsy specimens, a number of enzymes were simultaneously assayed: β-D-ghcosidase, β-D-galacto-sidase, β-D-hexosaminidase, β-D-glucuronidase, α-L-fucosidase, β-D-mannosidase, sphingo-myelinase and arylsulphatase A. The levels of the above enzymes were compared to those observed in tissue cultures of amniotic cells obtained through amniocentesis at 16–18 weeks of pregnancy. The amniotic sac remained intact in all cases of chorion biopsy. If the pregnancy was maintained after the biopsy, no spontaneous abortions were recorded, and pregnancies resulted in the timely delivery of full-term healthy infants. Therefore, the method described is a valuable means of diagnosing inherited disorders, with promising applications in prenatal medicine.     

Alpha-fetoprotein and acetylcholinesterase are not predictive of fetal junctional epidermolysis bullosa,Herlitz variant

Junctional epidermolysis bullosa, Herlitz variant (junctional EB-Herlitz) is a lethal autosomal recessive skin disorder currently amenable to prenatal diagnosis only by direct analysis of fetal skin. However, elevated levels of alpha-fetoprotein, as well as the presence of acetylcholinesterase in amniotic fluid, have been associated with other severe fetal genodermatoses. Fetal skin samplings were performed in ten pregnancies at risk for fetal junctional EB-Herlitz, with three fetuses affected on the basis of electron microscopic detection of blisters within the lamina lucida and abnormal hemidesmosomes. In neither affected nor unaffected pregnancies were maternal serum or amniotic fluid alpha-fetoprotein levels elevated. Moreover, alphafetoprotein levels in both maternal serum and amniotic fluid were not statistically different comparing affected and unaffected fetuses. Acetylcholinesterase was not present in the amniotic fluid samples of the three affected pregnancies. Unlike other severe fetal genodermatoses, neither alpha-fetoprotein nor acetylcholinesterase was predictive of junctional EB-Herlitz.