Prenatal diagnosis in a familial form of male pseudohermaphroditism due to 17-keto reductase deficiency

In an infant considered at birth as a female but with easily palpable gonads in the labia major, the XY karyotype and the endocrine studies (determination of plasma levels of steroid hormones under basal conditions and during hCG stimulation) were consistent with the diagnosis of male pseudohermaphroditism due to 17-keto reductase deficiency. During the second pregnancy an amniocentesis revealed a 46 XY karyotype. Endocrine studies performed on the amniotic fluid at midgestation suggested that the fetus was affected by the same enzyme defect. After birth, the diagnosis was demonstrated with anatomical an endocrine studies.     

Prenatal diagnosis of Sanfilippo disease type B

Summary The prenatal diagnosis of a fetus affected with Sanfilippo disease type B is described. The deficiency of -N-acetylglucosaminidase in the cultured amniotic fluid cells was shown by a microassay enabling early prenatal diagnosis. In addition an increased level of heparan sulphate was demonstrated in the amniotic fluid by two-dimensional electrophoresis of glycosaminoglycans. The latter result confirmed the value of this test as an adjunctive method in the prenatal diagnosis. The pregnancy was terminated and the prenatal diagnosis was confirmed by enzyme analysis of cultured fetal fibroblasts and fetal liver.     

Rapid prenatal diagnosis of HG-PRT deficiency using ultra-microchemical methods

Summary A previously developed simple ultramicromethod has been used for the rapid prenatal diagnosis of hypoxanthine-guanine phosphoribosyl transferase (HG-PRT) deficiency. The method is based on the incubation of small numbers of visually selected, lyophilized fibroblasts (in the present study five cells per incubation) with radioactive substrate in an end volume of 0.3 l. Fibroblasts derived from the amniotic fluid of a 15-week male fetus in a heterozygote for the X-linked Lesch-Nyhan syndrome showed a severe degree of HG-PRT deficiency. In total 50 fibroblasts were used. The diagnosis was confirmed upon termination of the pregnancy by the demonstration of HG-PRT deficiency in fetal erythrocytes and cultured skin fibroblasts.HG-PRT: hypoxanthine-guanine phosphoribosyl transferase     

First-trimester prenatal diagnosis of pyruvate kinase deficiency in an Indian family with the pyruvate kinase-Amish mutation

Pyruvate kinase (PK) deficiency is a rare red cell glycolytic enzymopathy. The purpose of the present investigation was to offer prenatal diagnosis for PK deficiency to a couple who had a previous child with severe enzyme deficiency and congenital non-spherocytic hemolytic anemia. PK deficiency was identified in the family by assaying the enzyme activity in red cells. Chorionic villus sampling was performed in an 11-week gestation and the mutation was located in exon 10 of the PKLR gene characterized by polymerase chain reaction and using restriction endonuclease digestion with the MspI enzyme, which was confirmed by DNA sequencing on the ABI 310 DNA sequencer. Both the parents were heterozygous for the 1436G-->A [479 Arg-->His] mutation in exon 10 and the proband was homozygous for this mutation. The fetus was also heterozygous for this mutation and the pregnancy was continued. Prenatal diagnosis allowed the parents with a severely affected child with PK deficiency to have the reproductive choice of having the fetus tested in a subsequent pregnancy.     

First trimester prenatal diagnosis of adrenoleukodystrophy by determination of very long chain fatty acid levels and by linkage analysis to a DNA probe

Summary A first trimester prenatal diagnosis of adrenoleukodystrophy has been done on chorionic villi biopsy in the pregnancy of a carrier woman. Two different approaches allowed one to determine that the male fetus was affected: the linkage analysis of DNA from chorionic villi using the highly polymorphic probe St 14 and the determination of very long chain fatty acid levels in cultured chorionic villi.     

Impact of prenatal diagnosis on livebirth prevalence of children with congenital anomalies

The objectives of this study were to describe the impact of prenatal diagnosis on the birth prevalence of congenital anomalies over 21 years (1979-1999) in a well defined population in northeastern France (13,500 births per year). The material for this study came from the analysis of data from multiple sources on births and terminations of pregnancy after prenatal diagnosis of congenital anomalies in 279,642 consecutive pregnancies of known outcome. The study period was divided into three subgroups 1979-1988, 1989-1993 and 1994-1999. Between 1979-1988, 1989-1993 and 1994-1999, prenatal detection of congenital anomalies increased, respectively, from 12.0% to 25.5% and to 31.7%. Termination of pregnancy (TOP) increased in the same proportions during the three time periods. However, the increase of TOP was much higher for chromosomal anomalies than for nonchromosomal congenital anomalies. The birth prevalence of Down's syndrome fell by 80% from 1979-1988 to 1994-1999. Sensitivity of prenatal detection of congenital anomalies and TOPs were lower for isolated cases (only one malformation present in the fetus) than for multiple malformations in the same fetus. Sensitivity varied with the type of malformations: it was high for neural tube defect (79.7%) and urinary anomalies (50.7%) and low for congenital heart defects (16.4%). In conclusion, the introduction of routine prenatal diagnosis has resulted in a significant fall in the birth prevalence of children with congenital anomalies. However, this fall varied with the types of congenital anomalies.     

Fetal DNA in maternal serum: does it persist after pregnancy?

Fetal DNA and cells present in maternal blood have previously been used for non-invasive prenatal diagnosis. However, some fetal cells can persist in maternal blood after a previous pregnancy. Fetal rhesus status and sex determination have been performed by using amplification by real-time polymerase chain reaction (PCR) of fetal DNA sequences present in maternal circulation; no false-positive results related to persistent fetal DNA from a previous pregnancy have been reported. This idea has recently been challenged. An SRY real-time PCR assay was performed on the serum of 67 pregnant women carrying a female fetus but having previously given birth to at least one boy and on the serum of 30 healthy non-pregnant women with a past male pregnancy. In all cases, serum was negative for the SRY gene. These data suggest that fetal DNA from a previous pregnancy cannot be detected in maternal serum, even by using a highly sensitive technique. Therefore, non-invasive prenatal diagnosis by fetal sex determination for women at risk of producing children with X-linked disorders, and fetal RHD genotyping is reliable and secure as previously demonstrated.     

Prenatal diagnosis in 200 pregnancies with a 1-in-4 risk of cystic fibrosis

Summary Prenatal diagnosis of cystic fibrosis was performed in 200 pregnancies with a 1-in-4 risk, and was based on significant modifications in amniotic fluid taken at 17, 18, 19 weeks of pregnancy, of six enzymatic assays: gamma-glutamyl-transpeptidase, aminopeptidase M, and alkaline phosphatase (total and isoenzymes). On the basis of normal values, normal outcome was predicted in 135 pregnancies reaching term, all the babies were normal. On the basis of significantly abnormal enzymatic values, an affected fetus was predicted in 56 pregnancies, 53 were terminated, and 3 went to term; the infants were affected. There were discrepancies in enzymatic values in nine cases, in eight cases normal outcome was predicted, six babies were normal and two were affected; in one case an affected baby was predicted, the pregnancy went to term and the baby is normal. Criteria giving evidence for cystic fibrosis in fetuses have been described: macroscopic observation of a typical meconium ileus, significant increase of albumin content in the meconium, and PAS-positive mucus-like material in some pancreatic acini. Using these criteria, diagnosis of cystic fibrosis has been confirmed in all the examined fetuses. The recurrence rate of cystic fibrosis was 22.5% in 147 diagnoses in which the index case had cystic fibrosis without a history of meconium ileus at birth, but was 47.5% when the index case had meconium ileus. The results of the study suggest that prenatal diagnosis of cystic fibrosis can be performed with an accuracy of 98%.     

A case of first trimester prenatal diagnosis of 21-hydroxylase deficiency with human complement C4 cDNA probe

Early prenatal diagnosis of 21-hydroxylase (21-OHase) deficiency would enable treatment to be done to protect the fetus from masculinization and/or life-threatening adrenal crisis at birth. We report here the prenatal diagnosis of 21-OHase deficiency with human complement component C4 cDNA to probe DNA from chorionic villi at 10 weeks of gestation. Southern analysis with human C4 cDNA identified TaqI restriction fragment length polymorphisms (RFLPs) in the family. Family analysis with these RELPs showed that the fetus was not affected at greater than 99% probability, because the frequency of recombination between the 21-OHase B gene and the C4 gene would be extremely low.     

Prenatal diagnosis of Duchenne muscular dystrophy by fetal muscle biopsy

Summary Prenatal diagnosis and carrier detection for Duchenne muscular dystrophy (DMD) usually can be performed using DNA analysis. When recombination occurs within the DMD gene, or DNA analysis is uninformative, or in pedigrees where it is unclear whether or not the consultand is a carrier, direct examination of muscle by dystrophin analysis may provide the only means of prenatal diagnosis. We present three cases representing each of these molecular genetic diagnostic dilemmas. In each instance, we used sonographically guided fetal muscle biopsy for dystrophin protein analysis to resolve the dilemma. In the first and third cases, the presence of normal dystrophin was shown by immunofluorescence and this was followed by delivery of an unaffected male fetus. In the second case, dystrophin was not found in fetal muscle tissue implying that this fetus was affected. The absence of dystrophin and affected status was confirmed in skeletal and cardiac muscle obtained after pregnancy termination.     

Genotyping and prenatal assessment of collagen lysyl hydroxylase deficiency in a family with Ehlers-Danlos syndrome type VI.

Collagen lysyl and prolyl hydroxylase activities were measured in cultured fibroblasts from a child with clinical features of Ehlers-Danlos syndrome. Lysyl-to-prolyl hydroxylase activity ratios in cells from the proband, mother, father, and control were .24, .86, .52, and 1.00, respectively, providing a biochemical diagnosis of Ehlers-Danlos syndrome type VI and indicating an autosomal recessive mode of inheritance in this family. Prenatal assessment of lysyl hydroxylase deficiency was requested and accomplished for the first time during a subsequent pregnancy in the family. A series of control cultures established lysyl hydroxylase activity to be similar in cultured amniotic fluid cells (AF and F cells) and in cultured dermal fibroblasts. Cultured F and AF cells from the monitored pregnancy had enzyme activity similar to controls, indicating that the fetus should not be affected by lysyl hydroxylase deficiency. This finding was confirmed by demonstration of normal lysyl hydroxylase activity in fibroblasts cultured from the newborn baby. These studies show that cells cultured from second trimester amniotic fluid have collagen lysyl hydroxylase activity similar to that in dermal fibroblasts, making prenatal diagnosis of lysyl hydroxylase deficiency possible.     

Prenatal diagnosis of ornithine transcarbamylase deficiency by using a single nucleated erythrocyte from maternal blood

We have developed a method that allows the prenatal DNA diagnosis of ornithine transcarbamylase (OTC) deficiency by using a single fetal nucleated erythrocyte (NRBC) isolated from maternal blood. OTC gene analysis of a male patient (TF) with early onset OTC deficiency was performed by single-strand conformation polymorphism (PCR-SSCP) and DNA sequencing. To investigate the possible prenatal diagnosis of OTC deficiency, maternal blood was obtained at 13 weeks of gestation of a subsequent pregnancy, from the mother of patient TF. NRBCs in the maternal blood were separated by using the density gradient method and then collected with a micromanipulator. The entire genome of a single NRBC was amplified by primer extension preamplification (PEP). The human leukocyte antigen (HLA)-DQ alpha genotype and sex were determined from small aliquots of the PEP product. The HLA-DQ alpha genotype of each of the parents of the male patient was also determined. Once a single NRBC had been identified as being of fetal origin, the OTC gene was analyzed by using the restriction fragment length polymorphism (RFLP) method. DNA analysis revealed a point mutation in exon 9 of the OTC gene in the OTC-deficient patient (TF). All NRBCs retrieved from maternal blood were successfully identified as being of fetal origin by HLA-DQ alpha genotyping and sex determination. RFLP analysis demonstrated that the fetal OTC gene was normal. This is the first study to successfully diagnose OTC deficiency prenatally, by using a single fetal NRBC from the maternal circulation. Such prenatal DNA diagnosis is non-invasive and can be applied to other genetic diseases, including autosomal and X-linked diseases. Received: 19 December 1997 / Accepted: 14 February 1998     

Prenatal diagnosis of triploidy by transabdominal aspiration of chorionic villi

A case of triploidy identified in second trimester fetal diagnosis is presented. Cytogenetic study was undertaken in chorionic willi obtained by transabdominal placentocentesis. The diagnosis was confirmed by cytogenetic analysis of cultured amniotic fluid cells. The observation was revealed within a programme of combined ultrasound and cytogenetic prenatal monitoring, in association with maternal age. The fetus aborted at 23 weeks of pregnancy was abnormal, including congenital malformations and hypoplasia of internal organs and placenta.     

Citrullinemia: prenatal diagnosis of an affected fetus.

We monitored a pregnancy in a family at risk for citrullinemia due to argininosuccinic acid (ASA) synthetase deficiency. ASA synthetase activity in cultured epithelioid amniotic fluid cells from the fetus at risk was less than 2% of control epithelioid amniotic fluid cell activity. An increased concentration of citrulline was found in the at-risk amniotic fluid (0.14 mumol/ml) as compared with fluid from six controls and one at-risk but unaffected pregnancy (trace). The pregnancy was terminated, and the in utero diagnosis was confirmed by assay of ASA synthetase activity in cultured fetal skin fibroblasts (4.4% of control activity). In addition, all five fetal tissues studied had significant accumulation of citrulline, whereas control fetal tissues had none. These data provide evidence that, if precise control is maintained over tissue culture variables, citrullinemia can be diagnosed successfully in utero by microassay of ASA synthetase activity in cultured amniotic fluid cells. They also suggest that amniotic fluid citrulline concentrations provide strong adjunctive evidence for this prenatal diagnosis.     

Cystic hygroma and multiple pterygium syndrome

We report the prenatal detection of a cystic hygroma in a 17 weeks gestation male foetus with multiple pterygium syndrome. Ultrasonographic study was performed in this pregnancy after the birth of a macerated, hydropic male foetus with large cystic nuchal hygroma in a previous pregnancy.     

Prenatal diagnosis for recessive dystrophic epidermolysis bullosa in 10 families by mutation and haplotype analysis in the type VII collagen gene (COL7A1).

BACKGROUND: Epidermolysis bullosa (EB) is a group of heritable diseases that manifest as blistering and erosions of the skin and mucous membranes. In the dystrophic forms of EB (DEB), the diagnostic hallmark is abnormalities in the anchoring fibrils, attachment structures beneath the cutaneous basement membrane zone. The major component of anchoring fibrils is type VII collagen, and DEB has been linked to the type VII collagen gene (COL7A1) at 3p21, with no evidence for locus heterogeneity. Due to life-threatening complications and significant long-term morbidity associated with the severe, mutilating form of recessive dystrophic EB (RDEB), there has been a demand for prenatal diagnosis from families with affected offspring. MATERIALS AND METHODS: Intragenic polymorphisms in COL7A1 and flanking microsatellite markers on chromosome 3p21, as well as detection of pathogenetic mutations in families, were used to perform PCR-based prenatal diagnosis from DNA obtained by chorionic villus sampling at 10-15 weeks or amniocentesis at 12-15 weeks gestation in 10 families at risk for recurrence of RDEB. RESULTS: In nine cases, the fetus was predicted to be normal or a clinically unaffected carrier of a mutation in one allele. These predictions have been validated in nine cases by the birth of a healthy child. In one case, an affected fetus was predicted, and the diagnosis was confirmed by fetal skin biopsy. CONCLUSIONS: DNA-based prenatal diagnosis of RDEB offers an early, expedient method of testing which will largely replace the previously available invasive fetal skin biopsy at 18-20 weeks gestation.     

Attempt at antenatal diagnosis of argininosuccinic aciduria]

Antenatal diagnosis in a woman previously delivered of a child with arginino-succinic aciduria, due to deficiency of arginino-succinase (EC 4.3.2.1.), showed the fetus to be unaffected. This was confirmed at birth.     

Extremely high prevalence of neural tube defects in a 4-county area in Shanxi Province, China

BACKGROUND: In the past, northern China's Shanxi Province has reported the highest incidence of neural tube defects (NTDs) in the world. However, little is known about the epidemiology of NTDs in this area in recent years. METHODS: Data were collected from a population-based birth defects surveillance system in 4 counties that captures information on all live births, stillbirths of at least 20 weeks' gestation, and pregnancy terminations at any gestational age resulting from prenatal diagnosis of a birth defect. We also surveyed mothers of NTD case patients to determine their use of folic acid before and during early pregnancy. RESULTS: During 2003, 160 NTD cases were identified among 11,534 births (NTD birth prevalence = 138.7/10,000 births). The rates of anencephaly, spina bifida and encephalocele were 65.9, 58.1, and 14.7 per 10,000, respectively, and a female predominance was observed among anencephaly cases (male-to-female relative risk [RR], 0.49; 95% confidence interval [CI], 0.30-0.79), but not among spina bifida (RR, 0.90; 95% CI, 0.55-1.45) and encephalocele (RR, 1.03; 95% CI, 0.40-2.69) cases. The percentages of pregnancy termination following prenatal diagnosis of anencephaly, spina bifida, and encephalocele were 50%, 41.8%, and 35.3%, respectively. NTD birth prevalence tended to be higher among mothers aged <20 or > or =30 years (P = .06) and was markedly associated with lower levels of maternal education (P < .001). Among 143 NTD mothers, only 6 (4.2%) used folic acid supplements during the periconceptional period. CONCLUSIONS: The NTD birth prevalence rate in the study area is among the highest worldwide. Folic acid deficiency may be one important risk factor.     

Prenatal diagnosis of congenital adrenal hyperplasia due to 21-hydroxylase deficiency by allele-specific hybridization and Southern blot

The feasibility and accuracy of gene-specific molecular genetic diagnosis for congenital adrenal hyperplasia due to 21-hydroxylase deficiency was studied in a group of 24 pregnancies at 25% risk of carrying an affected fetus. Chorionic villus sampling was performed at 9–10 weeks' gestation. Southern analysis and polymerase chain reaction, followed by allele-specific hybridization for a panel of nine known mutations, were performed for each family. Mutations were identified in 95% of chromosomes examined; the molecular diagnosis was accurate in 96% of infants as confirmed by postnatal examination. The most common mutation identified was an A-to-G transition at base 656 in the second intron, the result of an apparent gene conversion. In one family, there had been a de novo mutation in intron 2, which was detected in the proband, but not in the mother or in the fetus. We conclude that first trimester prenatal diagnosis of congenital adrenal hyperplasia due to 21-hydroxylase deficiency is feasible and accurate employing CYP21-specific probes.     

The role of immunocytochemistry and linkage analysis in the prenatal diagnosis of merosin-deficient congenital muscular dystrophy

Complete or partial deficiency of the laminin α2 chain of merosin has been demonstrated in a proportion of children with classical congenital muscular dystrophy and linkage to the laminin α2 chain gene (LAMA2) on chromosome 6q2 has been established. As the laminin α2 chain is also expressed in the trophoblast, its detection and linkage analysis are useful tools for prenatal diagnosis. We report our experience of seven prenatal diagnoses in families with partial deficiency or total absence of the laminin α2 chain in the muscle of the propositi. In five instances, expression of the laminin α2 chain in the trophoblast was normal and linkage data suggested that the fetuses were unaffected. In one family, the immunocytochemical studies of the trophoblast showed the absence of laminin α2, suggesting that the fetus was affected. Linkage analysis confirmed that the fetus had inherited the two at-risk haplotypes. In one family with partial laminin α2 chain deficiency, the haplotype analysis was hampered by maternal DNA contamination. Immunocytochemical analysis of chorionic villus sampling showed a reduction in laminin α2 expression. The pregnancy was presumed to be at high-risk and terminated. However, subsequent analysis of fetal DNA indicated that the fetus was probably heterozygous. Our data suggest that immunocytochemical analysis of the trophoblast can detect abnormalities in affected fetuses and gives normal results in unaffected and carrier fetuses. Nevertheless, we recommend that linkage analysis to the LAMA2 locus is also studied in all cases. Received: 2 October 1996 / Revised: 28 November 1996