Maternal transmission of interstitial 8p23.1 deletion detected during prenatal diagnosis

We report on the first prenatally diagnosed interstitial 8p23.1 maternally inherited deletion. At 20 weeks of gestation (WG) the fetus was diagnosed with a complete atrioventricular canal. In infancy, the mother underwent a two-step cardiac surgery for an interrupted aortic arch type A associated to an inlet ventricular septal defect (VSD). A straddling of the tricuspid valve type B was confirmed during surgery. The outcome showed no cardiac failure or conduction anomalies. However, she presented with moderate intellectual disability. Classical and molecular cytogenetic studies on amniotic and maternal lymphocytes cells showed a nearly identical interstitial deletion of the 8p23.1 region encompassing the GATA4 gene locus (Mother: nt 6,913,337-12,580,828, fetus: nt 7,074,449-12,580,828) with no modification of the telomeric region. The relevance of our report is not only the maternal syndromic interstitial 8p23.1 deletion, but also maternal transmission which has never been reported before. The maternal and fetal phenotypes were not identical, however, even though they had the same cellular and molecular background: an alteration of the epithelial mesenchymal transition of the atrioventricular valvulo-septal complex where GATA4 plays a positive role in the regulation. We reviewed all cases of interstitial 8p23.1 deletions diagnosed either prenatally or postnatally.

Binder phenotype: clinical and etiological heterogeneity of the so-called Binder maxillonasal dysplasia in prenatally diagnosed cases, and review of the literature

OBJECTIVE

Prenatal Binder profile is a well known clinical phenotype, defined by a flat profile without nasal eminence, contrasting with nasal bones of normal length. Binder profile results of a hypoplasia of the nasal pyramid (sometimes referred to as maxillonasal dysplasia). We report 8 fetuses prenatally diagnosed as Binder phenotype, and discuss their postnatal diagnoses.

METHODS

Ultrasonographic detailed measurements in 2D and 3D were done on the 8 fetuses with Binder profile, and were compared with postnatal phenotype.

RESULTS

All fetuses have an association of verticalized nasal bones, abnormal convexity of the maxilla, and some degree of chondrodysplasia punctata. The final diagnoses included fetal warfarin syndrome (one patient), infantile sialic acid storage (one patient), probable Keutel syndrome (one patient), and five unclassifiable types of chondrodysplasia punctata.

CONCLUSION

This series demonstrates the heterogeneity of prenatally diagnosed Binder phenotype, and the presence of chondrodysplasia punctata in all cases. An anomaly of vitamin K metabolism, possibly due to environmental factors, is suspected in these mild chondrodysplasia punctata. We recommend considering early prophylactic vitamin K supplementation in every suspected acquired vitamin K deficiency including incoercible vomiting of the pregnancy.

Contribution of diffusion-weighted imaging in the evaluation of diffuse white matter ischemic lesions in fetuses: correlations with fetopathologic findings

BACKGROUND AND PURPOSE

The sensitivity of fetal MR imaging is poor with regard to the evaluation of diffuse ischemic white matter (WM) abnormalities. Our purpose was to evaluate the contribution of diffusion-weighted imaging (DWI) in the analysis of microstructural changes in WM and to correlate neuroimaging with neurofetopathologic findings.

MATERIALS AND METHODS

We included fetuses with MR imaging, DWI, and a fetopathologic examination. In a region of interest defined by MR imaging, where T1 and T2 intensities were abnormal, the apparent diffusion coefficient (ADC) was measured and immunohistochemical analysis was performed. In fetuses with no WM abnormality in signal intensity, region of interest was defined at random. Histologic reading was performed with a complete blinding of the MR imaging results and ADC values. Three degrees of histologic appearance were defined with regard to vasogenic edema, astrogliosis, microgliosis, neuronal and oligodendrocytic abnormalities, and proliferation or congestion of vessels and were compared with a chi(2) test in groups A (normal ADC) and B (increased ADC) fetuses.

RESULTS

We included 12 fetuses in group A and 9 in group B, ranging from 29 to 38 weeks of gestation. All group B fetuses and 1 group A fetus demonstrated WM abnormalities in signal intensity. WM edema and astrogliosis were more common in group B than in group A (7/9 vs 2/12 and 8/9 vs 4/12, respectively). No significant difference was observed between both groups with regard to the other parameters.

CONCLUSION

This study showed a strong correlation between increased ADCs and 1) WM abnormalities in signal intensity on MR imaging, and 2) vasogenic edema with astrogliosis of the cerebral parenchyma.

Comparison between magnetic resonance imaging and fetopathology in the evaluation of fetal posterior fossa non-cystic abnormalities

OBJECTIVES

To compare magnetic resonance imaging (MRI) and fetopathological findings in the evaluation of non-cystic fetal posterior fossa anomalies and to describe associated abnormalities.

METHODS

This was a prospective study from 2000 to 2005 of fetuses identified on ultrasound as having sonographic suspicion of posterior fossa malformation. All underwent a thorough MRI examination of the fetal brain, after which we classified each fetus as presenting one of the following pathologies: vermian hypoplasia or agenesis, cerebellar and/or brain stem hypoplasia, destructive or dysplastic lesions. All of the pregnancies were then terminated, after which the whole fetus underwent fetopathological examination. We compared the findings from MRI and fetopathological examinations and recorded the associated cerebral and extracerebral abnormalities.

RESULTS

Twenty-five fetuses were included. MRI was performed at a mean gestational age of 31 weeks, and fetopathological examination at 33 weeks. In 12 cases we observed vermian hypoplasia, six had partial vermian agenesis, 11 had cerebellar hemisphere hypoplasia, seven had brain stem hypoplasia, four had destructive lesions and six had dysplastic lesions. The two techniques were similar in their performance with respect to the detection of vermian agenesis, brain stem hypoplasia and destructive lesions. There were four false-positive results of MRI for vermian hypoplasia and a poor agreement regarding cerebellar hemisphere hypoplasia. No dysplastic lesions were diagnosed by MRI. None of the posterior fossa malformations was isolated and many cerebral and extracerebral abnormalities were found.

CONCLUSION

A systematic analysis of the posterior fossa in fetal MRI makes it possible to diagnose accurately most posterior fossa malformations. These malformations never occurred in isolation in our study.

Detection of an Alu insertion in the POMT1 gene from three French Walker Warburg syndrome families

Walker Warburg syndrome (WWS) is the most severe of a group of multiple congenital disorders known as lissencephaly type II ( LIS Type II) associated with congenital muscular dystrophy and eye abnormalities. The POMT1 gene is the most frequently affected found in 20% of patients with WWS. We describe five fetuses with WWS in three non-related families carrying a same mutation in the POMT1 gene. All fetuses presented with tetra ventricular hydrocephaly, and arachnoidal neuroglial ectopia and cortical dysplasia characteristic of LIS type II. We performed sequencing of the POMT1 gene on fetal DNA. The five fetuses were found to share an insertion of an inversed Alu repeated DNA element within exon 3 of the POMT1 gene, all at the heterozygous state except one at the homozygous state. This mutation was associated with a common transition c.2203 C > T (p.Arg735Cys) in exon 20 on the same allele and similar intragenic haplotype, suggesting that the three families could be related or indicating a possible founder effect in France. Insertions of Alu sequences, which are rarely found in coding regions, have occasionally been reported to cause other genetic diseases. However, this is the first report of a retrotransposon insertion in the POMT1 gene associated with WWS.

Third-trimester fetal MRI in isolated 10- to 12-mm ventriculomegaly: is it worth it?

OBJECTIVE

The justification for magnetic resonance imaging (MRI) in isolated mild ventriculomegaly remains controversial. This study was undertaken to evaluate the contribution of third-trimester MRI in isolated 10- to 12-mm fetal ventriculomegaly.

DESIGN

Observational prospective cohort study.

SETTING

Universitary prenatal reference centre.

POPULATION

From February 2000 to May 2005, we prospectively collected data concerning fetuses referred to us for cerebral MRI following detection of ventriculomegaly by ultrasound scan (n= 310).

METHODS

Among these, we identified and analysed those cases in which ventriculomegaly was isolated and did not exceed 12 mm in ultrasound examinations prior to MRI scan (n= 185).

MAIN OUTCOME MEASURE

Cases in which MRI provided additional information that was likely to have an impact on prenatal management were detailed.

RESULTS

During the study period, 310 MRI were performed because of fetal ventriculomegaly. Hundred and eighty-five were suspected to be isolated 10- to 12-mm ventriculomegalies in ultrasound scan and formed our database. MRI confirmed the 10- to 12-mm isolated fetal ventriculomegaly in 106 cases (57.3%) and found other abnormalities in 5 (4.7%) of these 106 cases. MRI found ventricular measurement to be less than 10 mm in 43 cases (23.3%) and more than 12 mm in 36 cases (19.4%). Among these 36 fetuses with ventricle size more than 12 mm, 6 (16.7%) had other abnormalities, whereas MRI did not find other abnormalities in the 43 cases with ventricle size below 10 mm.

CONCLUSION

Before advantages of MRI to ultrasound examination can be demonstrated, it seems reasonable that MRI should remain an investigational tool, restricted to selected clinical situations in which the results are expected to modify case management. Where ultrasound scan suspects isolated ventriculomegaly of 10 to 12 mm, our data suggest that when the finding is confirmed with MRI this could be expected in around 5% of cases. Therefore, the policy of routine MRI in such cases should depend on prenatal centres' priorities.

Prenatal Marfan syndrome: report of one case and review of the literature

OBJECTIVES

Our objective was to describe the features of prenatal Marfan syndrome.

METHODS

Doppler fetal echocardiograms were performed. The morphology and rhythm of the fetal heart were examined sequentially.

RESULTS

The case was referred because of cardiomegaly and dilated great vessels. Sequential Doppler echocardiographic evaluation led to the diagnosis of prenatal Marfan syndrome. The main features are cardiomegaly, dysplastic atrioventricular valves with tricuspid regurgitation and dilated great vessels, which can be aneurysmal at their origin. The fetus died in utero at 39 weeks of gestation because of cardiac failure. Pathological study confirmed the Marfan habitus and complications. Molecular genetic study showed a de novo point mutation in exon 26 of the FBN1 gene.

CONCLUSION

We report a case of prenatal Marfan syndrome diagnosed by sequential evaluation of the cardiac signs, which are essential for prenatal diagnosis. The prognosis seems as poor as the neonatal one. The prenatal diagnosis is essential for adequate counselling.

C21orf5, a human candidate gene for brain abnormalities and mental retardation in Down syndrome

Mental retardation represents the more invalidating pathological aspect of trisomy 21 and has a hard impact on public health. The dosage imbalance of chromosome 21 genes could be the cause of neurological alterations and mental retardation seen in Down syndrome. We studied C21orf5 that we have demonstrated to be overexpressed in Down syndrome tissues, as a candidate gene for trisomy 21. A new optical technology (Rachidi et al., 2000) was used to compare signal intensity and cell density in presumptive embryonic brain compartments, at their boundaries and in higher specialized brain centres during fetal lifespan. We showed a developmentally regulated transcriptional activity of C21orf5 and a regional and cellular specific distribution of gene transcripts during human embryonic and fetal development. A wide but differential expression was detected in the nervous system during embryogenesis with a relatively lower level in the forebrain than in the midbrain and hindbrain and the highest transcription intensity in the future cerebellum. This developmentally regulated expression is maintained during post-embryogenesis and evolves selectively in fetal cerebral, hippocampal and cerebellar areas. Differential and cellular specificity were detected in hippocampus with higher C21orf5 mRNA level in the pyramidal cells compared to granular cells of the dentate gyrus. The expression pattern detected in cortical and cerebellar structures correlates well to the altered cortical lamination and to the lower size of the cerebellum observed in Down syndrome patients. In addition, the patterned differential expression detected in the medial temporal-lobe system, including hippocampal formation and perirhinal cortex, working as control centres of the memory circuits and involved in cognitive processes and memory storage, also corresponds to abnormal brain regions seen in Down syndrome patients. The C21orf5 selective expression in the key brain structures for learning and memory suggests that C21orf5 overexpression could participate in mental retardation pathogenesis in Down syndrome patients.

Phenotypic spectrum of CHARGE syndrome in fetuses with CHD7 truncating mutations correlates with expression during human development

BACKGROUND

The acronym CHARGE refers to a non-random cluster of malformations including coloboma, heart malformation, choanal atresia, retardation of growth and/or development, genital anomalies, and ear anomalies. This set of multiple congenital anomalies is frequent, despite rare patients with normal intelligence, and prognosis remains poor. Recently, CHD7 gene mutations have been identified in CHARGE patients; however, the function of CHD7 during development remains unknown.

METHODS

We studied a series of 10 antenatal cases in whom the diagnosis of CHARGE syndrome was suspected, considering that a careful pathological description would shed light on the CHD7 function during development. CHD7 sequence analysis and in situ hybridisation were employed.

RESULTS

The diagnosis of CHARGE syndrome was confirmed in all 10 fetuses by the identification of a CHD7 heterozygous truncating mutation. Interestingly, arhinencephaly and semi-circular canal agenesis were two constant features which are not included in formal diagnostic criteria so far. In situ hybridisation analysis of the CHD7 gene during early human development emphasised the role of CHD7 in the development of the central nervous system, internal ear, and neural crest of pharyngeal arches, and more generally showed a good correlation between specific CHD7 expression pattern and the developmental anomalies observed in CHARGE syndrome.

CONCLUSIONS

These results allowed us to further refine the phenotypic spectrum of developmental anomalies resulting from CHD7 dysfunction.

[Ductus venosus agenesis]

OBJECTIVE

Congenital absence of the ductus venosus is a rare anomaly in the fetus. The aim of our study was to evaluate the clinical and ultrasonographic features and outcome of the fetuses with ductus venosus agenesis.

STUDY DESIGN

We describe 12 cases in the period between 1992 and 2004. The umbilical vein drained either into the right atrium directly (2 cases) or by the coronary sinus (1 case), or in the inferior vena cava (5 cases), or in the azygos vein (1 case), or in the portal vein (3 cases). Our data where analyzed with the cases published in the literature. Two groups of anastomoses where defined on the basis of the hemodynamic consequences: the group of extrahepatic anastomoses (53 cases) and the group of intrahepatic anastomoses (22 cases).

RESULTS

In the group of extra hepatic anastomoses, cardiomegaly was the most common antenatal finding (39%), while in the intra hepatic group hydrops fetalis occurred most frequently (23%). Malformation rate was high in both groups (56% and 45%) and chromosomal anomalies where present in 9% of cases.

CONCLUSION

Careful assessment of the umbilical venous return and the ductus venosus should be a part of examination of every fetus with cardiomegaly, polyhydramnios, ascites or hydrops. In case of absence of the ductus venosus a referral scan, a fetal echocardiography and a karyotype should be performed.

Prenatal rupture of a left ventricular diverticulum: a case report and review of the literature

Congenital left ventricular diverticulum is a rare malformation. We report a case of a ruptured congenital left ventricular diverticulum in a 24-week-old fetus. The fetus was referred for a large and circumferential pericardial effusion confirmed by cross-sectional echocardiography in our tertiary fetal cardiology unit. Pericardiocentesis removed 25 mL of old hematic fluid. The fetus died 5 days later. The pathological examination showed a ruptured submitral fibrous diverticulum of the posterior wall of the left ventricle. There is no previous report in the literature of prenatal rupture of a cardiac diverticulum. The submitral location and the fibrous wall of the diverticulum is uncommon. As regards this case, we reviewed the diagnostic criteria and the outcome of 11 cases of prenatal cardiac diverticulum reported in the literature.

Chromosome 21 KIR channels in brain development

Two KIR (K+ Inwardly Rectifying) channel genes have been identified on chromosome 21, in a region associated with important phenotypic features of trisomy 21, including mental retardation: KIR3.2 (GIRK2) and KIR4.2. We analysed the expression of these channel genes in developing human and mouse brains to determine the possible role of the corresponding channels in brain development and function. KIR3.2, which has been extensively studied in the mouse, was found to be expressed in the human cerebellum during development. The KIR4.2 channel is expressed later in development in both mice and humans. We compared the expression of these channels in terms of RNA and protein levels and discussed the potential synergy and consequences of the overexpression of these channels in Down's syndrome brain development.

Infections néonatales à Candida

Candida infections in newborns are classified, as bacterial ones, in early onset or maternofoetal infections and late onset diseases, primitive and nosocomial. Candida infections are responsible of less than 1% of early onset sepsis. Their diagnosis is facilitated by suggestive cutaneous lesions which can be associated or not with systemic infection. Candida nosocomial infections are the most frequent, 7% in premature infants < 1500 g; they are associated with a central venous catheter or with cutaneous infection in extremely low birth weight infants. C. albicans is the predominant species in maternofoetal infections, contrary to nosocomial ones where C. parapsilosis is predominant, 60%. Both species are sensitive to fluconazole. Amphotericin B and its lipidic derivative Ambisome is the reference drug. Because of its lower toxicity and simplicity of administration, fluconazole is preferable for sensitive species. Its prophylactic use in colonized premature infants has been recently proposed.

Standards for dysmorphological diagnosis in human fetuses

This study provides new standards for some fetal dimensions frequently concerned with dysmorphological syndromes. Seven dimensions were included: the outer and inner canthal distances (OCD and ICD), the anteroposterior and transversal ocular diameters, the biparietal diameter and head circumference, and the inter-nipple distance. Subjects came from a large data set including more than 4000 fetuses autopsied in fetopathology units of pediatric hospitals in Paris between 1986 and 2001. From this data set, 673 subjects were carefully selected by exclusion of multiple pregnancies, macerated and malformed fetuses, and subjects with abnormal karyotypes and severe infections. Fetal ages ranged from 11 to 42 gestational wk, with a very large sample of fetuses in the first half of gestation. The standards of each dimension were computed in relation to age, as well as the ratio ICD/OCD. The mathematical models used to fit the percentile growth curves were carefully selected for each variable. This study supplies a set of accurate standards of specific dimensions useful for dysmorphological diagnosis in fetuses.

Absence of functional type 1 parathyroid hormone (PTH)/PTH-related protein receptors in humans is associated with abnormal breast development and tooth impaction

Recent studies in transgenic mice have demonstrated that PTH-related protein (PTHrP), signaling through the type 1 PTH/PTHrP receptor (PTHR1), regulates endochondral bone development and epithelial-mesenchymal interactions during the formation of the mammary glands and teeth. Recently, it has been shown that loss-of-function mutations in the PTHR1 gene result in a rare, lethal form of dwarfism known as Blomstrand chondrodysplasia. These patients suffer from severe defects in endochondral bone formation, but abnormalities in breast and tooth development have not been reported. To ascertain whether PTHrP signaling was important to human breast and tooth development, we studied two fetuses with Blomstrand chondrodysplasia. These fetuses lack nipples and breasts. Developing teeth were present, but they were severely impacted within the surrounding alveolar bone, leading to distortions in their architecture and orientation. Compatible with the involvement of PTHR1 and PTHrP in human breast and tooth morphogenesis, both were expressed within the developing breasts and teeth of normal human fetuses. Therefore, impairment of the PTHrP/PTHR1 signaling pathway in humans is associated with severe abnormalities in tooth and breast development. In addition to regulating human bone formation, this signaling pathway is also necessary for the normal development of the human breast and tooth.

C21orf5, a novel human chromosome 21 gene, has a Caenorhabditis elegans ortholog (pad-1) required for embryonic patterning

To contribute to the development of the transcription map of human chromosome 21 (HC21), we isolated a new transcript, C21orf5 (chromosome 21 open reading frame 5), encoding a predicted 2298-amino-acid protein. Analysis of the genomic DNA sequence revealed that C21orf5 consists of 37 exons that extend over 130 kb and maps between the CBR3 (carbonyl reductase 3) and the KIAA0136 genes. Northern blot analyses showed a ubiquitously expressed RNA species of 8.5 kb. RNA in situ hybridization on brain sections of normal human embryos revealed a strong labeling in restricted areas of the cerebral cortex. In silico analysis of the deduced C21orf5 protein revealed several highly probable transmembrane segments but no known protein domains or homology with known proteins. However, there were significant homologies to several hypothetical Caenorhabditis elegans proteins and Drosophila melanogaster genomic sequences. To investigate the function of C21orf5, we isolated the cDNA of the C. elegans ortholog and performed double-stranded RNA-mediated genetic interference experiments. The major phenotype observed in the progeny of injected animals was embryonic lethality. Most of the tissues of the embryo failed to undergo proper patterning during gastrulation, and morphogenesis did not occur; thus we termed the ortholog pad-1, for patterning defective 1. These results indicated that pad-1 is essential for the development and the survival of C. elegans. This study provides the first example of the use of C. elegans as a model to study the function of genes on human chromosome 21 that might be involved in Down syndrome.

EXT 1 gene mutation induces chondrocyte cytoskeletal abnormalities and defective collagen expression in the exostoses

Hereditary multiple exostoses (HME), an autosomal skeletal disorder characterized by cartilage-capped excrescences, has been ascribed to mutations in EXT 1 and EXT 2, two tumor suppressor-related genes encoding glycosyltransferases involved in the heparan sulfate proteoglycan (HSPG) biosynthesis. Taking advantage of the availability of three different exostoses from a patient with HME harboring a premature termination codon in the EXT 1 gene, morphological, immunologic, and biochemical analyses of the samples were carried out. The cartilaginous exostosis, when compared with control cartilage, exhibited alterations in the distribution and morphology of chondrocytes with abundant bundles of actin filaments indicative of cytoskeletal defects. Chondrocytes in the exostosis were surrounded by an extracellular matrix containing abnormally high amounts of collagen type X. The unexpected presence of collagen type I unevenly distributed in the cartilage matrix further suggested that some of the hypertrophic chondrocytes detected in the cartilaginous caps of the exostoses underwent accelerated differentiation. The two mineralized exostoses presented lamellar bone arrangement undergoing intense remodeling as evidenced by the presence of numerous reversal lines. The increased electrophoretic mobility of chondroitin sulfate and dermatan sulfate proteoglycans (PGs) extracted from the two bony exostoses was ascribed to an absence of the decorin core protein. Altogether, these data indicate that EXT mutations might induce a defective endochondral ossification process in exostoses by altering actin distribution and chondrocyte differentiation and by promoting primary calcification through decorin removal.

Expression of the PAX2 gene in human embryos and exclusion in the CHARGE syndrome

The CHARGE syndrome comprises ocular coloboma, heart malformation, choanal atresia, retarded growth and development, central nervous system malformations, genital hypoplasia, ear abnormalities, or deafness. The cause of the CHARGE syndrome remains unknown. In the present study, we analyzed the distribution pattern of the PAX2 gene in human embryos and found that PAX2 gene expression occurs in the primordia affected in the CHARGE syndrome. These data prompted us to consider the PAX2 gene a candidate gene in the CHARGE "association." We analyzed the PAX2 gene in 34 patients fulfilling the diagnostic criteria of the CHARGE syndrome for deletion and nucleotidic variations of the coding sequence and identified only polymorphisms. Our data suggest that mutation of the PAX2 gene is not a cause of the CHARGE association. However, the pattern of expression of PAX2 suggests that genes encoding downstream targets effectors could be candidate genes for the CHARGE syndrome.

Developmentally regulated expression of the murine ortholog of the potassium channel KIR4.2 (KCNJ15)

The gene KIR4.2 (K(+) inwardly rectifying channel 4.2) has been recently identified in the Down syndrome Chromosome Region 1. We have cloned the mouse ortholog of KIR4.2 and characterized its expression pattern. In situ hybridization showed a restricted and developmentally regulated pattern of expression. The expression is starting at E12.5 and expands at E14.5 in different tissues and organs, which may be affected in Down syndrome: heart, thymus, thyroid gland, and perichondrium. At E17.5, additional epithelia (kidney, bladder, stomach, lung) expressed also strongly the gene.

Calpain3 expression during human cardiogenesis

Transcripts of calpain3, the gene involved in limb girdle muscular dystrophy type 2A, appear in organs other than the skeletal muscle during human development, the first of which being the early embryonic heart. We examined more precisely the spatio-temporal transcription pattern of calpain3 during human cardiogenesis and the appearance of its protein in fetal tissues, and correlated it to titin expression. Different events of the heart's maturation can be recognized: (i) the presence of titin RNA or protein constitute very precocious developmental cardiac markers appearing before the fusion of the two lateral endocardial tubes; (ii) the disappearance of calpain3 RNA from the ventricular compartment later in the embryonic heart. Finally, although calpain3 transcripts are present in the heart, the corresponding protein is not detected elsewhere than in skeletal muscle.

Subtle familial unbalanced translocation t(8;11)(p23.2;p15.5) in two fetuses with Beckwith-Wiedemann features

We describe a subtle translocation t(8;11)(p23.2;p15.5) ascertained after two induced abortions in the same sibship because of the discovery of fetal hydrops on ultrasound examination. Initial cytogenetic studies performed on cultured amniotic fluid cells were considered as normal in both fetuses. High resolution banding analysis and FISH studies performed on the parents' chromosomes revealed a paternal translocation t(8;11)(p23.2;p15.5). Retrospective FISH analysis of both fetuses showed that they carried the same chromosomal imbalance including a distal monosomy 8pter and a distal trisomy 11pter. The phenotypes of the fetuses were re-examined and found to be compatible with Beckwith-Wiedemann syndromes (BWS). FISH analysis using an IGF2 probe demonstrated the presence of three copies of the IGF2 gene. This study highlights the value of searching for subtle chromosome rearrangements in families with recurrent unexplained multiple malformation syndromes discovered prenatally. Also, it contributes to a better delineation of the prenatal phenotype of BWS. Finally, it sheds new light on the aetiology of non-immune hydrops fetalis.

Regional and cellular specificity of the expression of TPRD, the tetratricopeptide Down syndrome gene, during human embryonic development

The TPRD gene (tetratricopeptide (TPR) containing Down syndrome gene) is one of the candidate genes in the Down syndrome chromosomal region-1. Duplication of this gene may be the cause of major phenotypic features of Down syndrome. Here we show that the TPRD expression is developmentally regulated during human embryogenesis. At the earliest stages of development (Carnegie 8-12) TPRD expression is ubiquitous. At later developmental stages (Carnegie stages 14, 16 and 18), it becomes restricted to the nervous system, as is the case for the mtprd gene during mouse development. We extended our analysis of TPRD expression during fetal development of the human nervous system (13, 22 and 24 weeks). A new oblique illumination technique was used to compare signal intensity and cell density. Some regions of the nervous system such as the external cortical layers of the brain, and the inner neuroblastic layer of the eye, strongly express the TPRD gene.

Ultrastructural evaluation of lung maturation in a sheep model of diaphragmatic hernia and tracheal occlusion

In fetuses with diaphragmatic hernia (DH) lung development is impaired, and pulmonary hypoplasia is one of the main factors responsible for the poor outcome of the disease. A possible treatment consists of occluding trachea during lung development to retain pulmonary fluid and to force the lung to expand. Although it appeared promising at first, this technique has recently been reported to decrease type II cell number and to induce surfactant deficiency. The aim of this study was to investigate lung maturation further through ultrastructural examination in a fetal lamb model of DH created at 85 d, followed or not by endoscopic balloon tracheal occlusion (TO) at 120 d of gestation. The proportion of alveolar epithelial type I and type II cells was altered by both treatments: the type I/type II cell ratio, which was about 2 in control lungs, was decreased 4.5-fold in DH lungs but was increased 4.5-fold in DH+TO lungs. The proportion of undifferentiated cells was increased in DH lungs. Indeterminate cells sharing features of type II and type I cells that were not observed in controls were seldom seen in DH lungs and were numerous in DH+TO lungs. The number of lamellar bodies per type II cell was decreased in both DH and DH+TO groups. In DH lungs, wall structure presented an immature appearance, with cellular connective tissue and poor secondary septation of saccules. In DH+TO lungs, primary septa appeared more mature, with reduced connective tissue, but secondary septa were still buds, although elastin was present at their tips. A single capillary layer was found in all three groups (control, DH, and DH+TO) with no sign of septal capillary pairing. This first investigation in DH and DH+TO lungs through transmission electron microscopy thus enabled us to show that compression and forced expansion of the lung are both responsible for alterations in type II cell differentiation and septal development.

Clinical variability in patients with Apert's syndrome

OBJECT

Apert's syndrome is characterized by faciocraniosynostosis and severe bony and cutaneous syndactyly of all four limbs. The molecular basis for this syndrome appears remarkably specific: two adjacent amino acid substitutions (either S252W or P253R) occurring in the linking region between the second and third immunoglobulin domains of the fibroblast growth factor receptor (FGFR)2 gene. The goal of this study was to examine the phenotype/genotype correlations in patients with Apert's syndrome.

METHODS

In the present study, 36 patients with Apert's syndrome were screened for genetic mutations. Mutations were detected in all cases. In one of the patients there was a rare mutation consisting of a double-base pair substitution in the same codon (S252F). A phenotypical survey of our cases was performed and showed the clinical variability of this syndrome. In two patients there was no clinical or radiological evidence of craniosynostosis. In two other patients with atypical forms of syndactyly and cranial abnormalities, the detection of a specific mutation was helpful in making the diagnosis.

CONCLUSIONS

The P253R mutation appears to be associated with the more severe forms, with regard to the forms of syndactyly and to mental outcome. The fact that mutations found in patients with Apert' s syndrome are usually confined to a specific region of the FGFR2 exon IIIa may be useful in making the diagnosis and allowing genetic counseling in difficult cases.

A new lethal syndrome of exomphalos, short limbs, and macrogonadism

We report a new lethal multiple congenital abnormality (MCA) syndrome of exomphalos, short limbs, nuchal web, macrogonadism, and facial dysmorphism in seven fetuses (six males and one female) belonging to three unrelated families. X rays showed enlarged and irregular metaphyses with a heterogeneous pattern of mineralisation of the long bones. Pathological examination showed adrenal cytomegaly, hyperplasia of Leydig cells, ovarian stroma cells, and Langherans cells, and renal microcysts. We suggest that this condition is a new autosomal recessive MCA syndrome different from Beckwith-Wiedemann syndrome, especially as no infracytogenetic deletion or uniparental disomy of chromosome 11 was found.

Expression of the RET proto-oncogene in human embryos

The patterns of RET proto-oncogene expression in mouse, rat, and chicken and the anomalies observed in targeted RET mutants suggest that RET plays a major role in development of mouse enteric nervous system and in kidney organogenesis. Here, we report on in situ hybridization studies describing the pattern of RET proto-oncogene expression during early development of human embryos between 23 and 42 days. We show that the RET gene is expressed in the developing kidney (nephric duct, mesonephric tubules, and ureteric bud), the presumptive enteric neuroblasts of the developing enteric nervous system, cranial ganglia (VII+VIII, IX, and X) and in the presumptive motor neurons of the spinal cord. Yet, despite the high level of RET gene expression in the kidney and in the motor neurons of the developing central nervous system in human embryos, only rare cases with renal agenesis have been reported in Hirschsprung disease patients, and no clinical evidence of spinal cord involvement has been shown in patients carrying RET germline mutations (i.e., multiple endocrine neoplasia syndromes and Hirschsprung disease).

The distribution of SMN protein complex in human fetal tissues and its alteration in spinal muscular atrophy

Spinal muscular atrophy (SMA) is a common autosomal recessive neuromuscular disorder characterized by degeneration of motor neurons of the spinal cord and muscular atrophy. SMA is caused by alterations to the survival of motor neuron (SMN) gene, the function of which has hitherto been unclear. Here, we present immunoblot analyses showing that normal SMN protein expression undergoes a marked decay in the postnatal period compared with fetal development. Morphological and immunohistochemical analyses of the SMN protein in human fetal tissues showed a general distribution in the cytoplasm, except in muscle cells, where SMN protein was immunolocalized to large cytoplasmic dot-like structures and was tightly associated with membrane-free heavy sedimenting complexes. These cytoplasmic structures were similar in size to gem. The SMN protein was markedly deficient in tissues derived from type I SMA fetuses, including skeletal muscles and, as previously shown, spinal cord. While our data do not help decide whether SMA results from impaired SMN expression in spinal cord, skeletal muscle or both, they suggest a requirement for SMN protein during embryo-fetal development.

Presentation of six cases of Stüve-Wiedemann syndrome

Stüve-Wiedemann syndrome (SWS) is a rare disorder characterized by bowing of the long bones, camptodactyly, respiratory distress, hyperthermic episodes and early lethality. We report six additional cases of SWS, suggesting that this syndrome is homogeneous. All patients had feeding and swallowing difficulties, respiratory insufficiency, dysmorphic features and radiolucent metaphyses with abnormal trabecular pattern. Recurrent episodes of unexplained fever was the cause of death in almost all cases. Parental consanguinity and recurrence in sibs is highly suggestive of autosomal recessive inheritance.

Insulin-like 4 (INSL4) gene expression in human embryonic and trophoblastic tissues

Polypeptide growth factors play an important role in the regulation of human embryonic development. Insulin-like 4 gene (INSL4) is a member of the insulin family, which includes insulin, IGF-I, IGF-II, relaxin, and INSL3. Using RT-PCR, we previously found abundant INSL4 mRNA in the human placenta. In this study, we examined the chronology and spatial expression of this gene in sections of human placenta and conceptus by means of in situ hybridization. Expression of the IGF-II gene was studied as a positive control. INSL4 distribution was tissue- and cell-specific. Indeed, INSL4 mRNA was most abundant in syncytiotrophoblast cells. In fetal tissues, INSL4 mRNA was identified in the perichondrium of all four limbs, vertebrae, and ribs. Moreover, INSL4 mRNA was abundant in interbone ligaments. These findings indicate that the INSL4 gene may play an important role in trophoblast development and regulation of bone formation. IGF-II mRNA, in agreement with the literature, are mainly located in the mesodermal core in the villous trophoblast and in most embryonic tissues.

Spatio-temporal expression of FGFR 1, 2 and 3 genes during human embryo-fetal ossification

Mutations in FGFR 1-3 genes account for various human craniosynostosis syndromes, while dwarfism syndromes have been ascribed exclusively to FGFR 3 mutations. However, the exact role of FGFR 1-3 genes in human skeletal development is not understood. Here we describe the expression pattern of FGFR 1-3 genes during human embryonic and fetal endochondral and membranous ossification. In the limb bud, FGFR 1 and FGFR 2 are initially expressed in the mesenchyme and in epidermal cells, respectively, but FGFR 3 is undetectable. At later stages, FGFR 2 appears as the first marker of prechondrogenic condensations. In the growing long bones, FGFR 1 and FGFR 2 transcripts are restricted to the perichondrium and periosteum, while FGFR 3 is mainly expressed in mature chondrocytes of the cartilage growth plate. Marked FGFR 2 expression is also observed in the periarticular cartilage. Finally, membranous ossification of the skull vault is characterized by co-expression of the FGFR 1-3 genes in preosteoblasts and osteoblasts. In summary, the simultaneous expression of FGFR 1-3 genes in cranial sutures might explain their involvement in craniosynostosis syndromes, whereas the specific expression of FGFR 3 in chondrocytes does correlate with the involvement of FGFR 3 mutations in inherited defective growth of human long bones.

Clinical homogeneity of the Stüve-Wiedemann syndrome and overlap with the Schwartz-Jampel syndrome type 2

The Stüve-Wiedemann syndrome (SWS) is a rare disorder characterized by respiratory distress, hyperthermic episodes, and early lethality and radiologically by bowing of the long bones with internal cortical thickening and large metaphyses. We report findings in 8 new patients suggesting that this syndrome is clinically homogeneous. All patients had feeding and swallowing difficulties, respiratory insufficiency, abnormal appearance, muscle hypotonia, and postnatal short stature. Recurrent episodes of unexplained fever occurred in all and were the cause of death in 6 of 8 cases. Parental consanguinity and sib recurrence suggest autosomal recessive inheritance. The clinical, radiological, and histological similarities between our patients with SWS and those with the recently delineated "neonatal" Schwartz-Jampel syndrome (SJS type 2) lead us to suggest that SWS and SJS type 2 may be a single entity.

Fibroblast growth factor receptor 3 mutations promote apoptosis but do not alter chondrocyte proliferation in thanatophoric dysplasia

Thanatophoric dysplasia (TD) is a lethal skeletal disorder caused by recurrent mutations in the fibroblast growth factor receptor 3 (FGFR 3) gene. The mitogenic response of fetal TD I chondrocytes in primary cultures upon stimulation by either FGF 2 or FGF 9 did not significantly differ from controls. Although the levels of FGFR 3 mRNAs in cultured TD chondrocytes were similar to controls, an abundant immunoreactive material was observed at the perinuclear level using an anti-FGFR 3 antibody in TD cells. Transduction signaling via the mitogen-activated protein kinase pathway was assessed by measuring extracellular signal-regulated kinase activity (ERK 1 and ERK 2). Early ERKs activation following FGF 9 supplementation was observed in TD chondrocytes (2 min) as compared with controls (5 min) but no signal was detected in the absence of ligand. By contrast ligand-independent activation of the STAT signaling pathway was demonstrated in cultured TD cells and confirmed by immunodetection of Stat 1 in the nuclei of hypertrophic TD chondrocytes. Moreover, the presence of an increased number of apoptotic chondrocytes in TD fetuses was associated with a higher expression of Bax and the simultaneous decrease of Bcl-2 levels. Taken together, these results indicate that FGFR 3 mutations in TD I fetuses do not hamper chondrocyte proliferation but rather alter their differentiation by triggering premature apoptosis through activation of the STAT signaling pathway.

MR imaging of fetal cerebral anomalies

BACKGROUND

Prenatal diagnosis of fetal brain anomalies relies mainly upon ultrasonography. However, even in the most experienced hands, the technique has limitations for some difficult diagnoses. MRI is an excellent imaging modality for the paediatric and adult brain.

OBJECTIVE

To assess the value of prenatal MRI when a cerebral anomaly was detected by US and where the prognosis depended on the identification of other anomalies undetectable by US, or where fetuses were at risk for a CNS lesion even when the US was normal.

MATERIALS AND METHODS

Four hundred prenatal MRI examinations were performed since 1988, and confirmed by postnatal follow-up or pathological examination. Two-thirds of the examinations were performed after 25 weeks of gestation, one-third between 21 and 26 weeks. Fetal immobilisation was obtained by maternal premedication with flunitrazepam, administered orally 1 h before the examination. The examinations were performed on 1.5 T scanners using one or two surface coils.

RESULTS

Prenatal MRI allowed the diagnosis of serious unsuspected lesions such as neuronal migration disorders, ischaemic and haemorrhagic lesions and the abnormalities observed in tuberous sclerosis. It helped to characterise ventricular dilatation and anomalies of the corpus callosum and of the posterior fossa.

CONCLUSIONS

MRI is a valuable complementary tool when prenatal US is incomplete, doubtful or limited. Prenatal MRI is particularly useful for the detection of ischaemic and haemorrhagic lesions, neuronal migration disorders and tuberous sclerosis lesions. Detection of these associated anomalies worsens the fetal prognosis, has medico-legal implications and modifies obstetric management. Normal prenatal MRI does not exclude an anomaly.

Lung growth and maturation after tracheal occlusion in diaphragmatic hernia

Tracheal occlusion (TO) was performed at 120 d of gestation by noninvasive endoscopic technique using a releasable latex balloon, in fetal lambs with diaphragmatic hernia (DH) established at 85 d. The lungs were studied at 139 d in five fetuses with DH + TO, five fetuses with DH only, and six control fetuses. Fluid retention consecutive to TO allowed fetal lungs to grow. Histological pulmonary structure was more mature in DH + TO than in DH alone. The growth-inducing effect of TO was however incomplete, with an increased protein/DNA ratio. Tissue phospholipids were increased, but this was not reflected in the surfactant compartment. The major surfactant component, disaturated phosphatidylcholine, was reduced to 58% of its control value in DH, and further reduced to 17.5% of its control value in DH + TO. The proportion of surfactant protein B immunoreactive cells, assumed to represent the proportion of type II cells, was increased in DH (27% of all parenchymal cells), and reduced in DH + TO (7.8%) as compared with control fetuses (15%). In conclusion, although noninvasive tracheal occlusion in utero is feasible and may partly compensate the adverse effects of DH on lung organogenesis, it reduces the number of type II cells and induces a dramatic surfactant deficit. Using this technique in human fetuses requires careful consideration until further evaluation of lung functional characteristics has been achieved in this experimental model.

Expression of genes (CAPN3, SGCA, SGCB, and TTN) involved in progressive muscular dystrophies during early human development

The developmental expression pattern of four human genes, three of which are involved in progressive muscular dystrophies, was investigated. The rationale for these experiments is that these patterns might provide useful information on the pathophysiology underlying these myopathies. Despite the presence of overlapping clinical signs, the spatiotemporal expression profiles of the corresponding genes differed widely. Transcripts of alpha-sarcoglycan (SGCA) were visible as soon as myotomes were formed, and constitute, together with titin transcripts, precocious muscular system landmarks. beta-sarcoglycan (SGCB) was initially transcribed in a ubiquitous manner, and, toward the second part of the embryonic period, became specific to striated muscle, heart, and the central nervous system. Whereas titin (TTN) transcription and translation seem to be coupled, for the sarcoglycans, translation seemed restricted to skeletal muscle. Calpain3 (CAPN3) RNA was found in only skeletal muscles during the fetal period. It was, however, present earlier in the whole heart, where it selectively disappeared. Finally, evidence for differentially spliced calpain3 variants in smooth muscles was also seen. The expression profiles of these genes is suggestive of their having a role during myogenesis, knowledge of which could be pertinent to the understanding of the pathophysiology of the associated diseases.

Cardiac myosin binding protein C gene is specifically expressed in heart during murine and human development

Cardiac myosin binding protein C (MyBP-C) is a substantial component of the sarcomere, with both structural and regulatory roles. The gene encoding cardiac MyBP-C in humans is located on chromosome 11p11.2, and mutations that are most predicted to produce truncated proteins have been identified in this gene in unrelated families with familial hypertrophic cardiomyopathy (FHC). To understand better the pathophysiology of FHC and with a view to the development of animal models for this disease, we have investigated by in situ hybridization the pattern of expression of the cardiac MyBP-C gene during human and mouse development using species-specific oligonucleotide probes. From 4 weeks of human development, a strong labeling of cardiac MyBP-C mRNAs was unambiguously detected in all heart compartments, and no signal could be visualized in somites. In murine embryos, from embryonic day 9.5 until birth, a strong signal was detected exclusively in the heart. Our results showed that during both human and murine development, in contrast to chicken development, the cardiac MyBP-C gene is abundantly and specifically expressed in the heart.

Screening of the C677T mutation on the methylenetetrahydrofolate reductase gene in French patients with neural tube defects

We report the analysis of the distribution of the C677T mutation on the methylenetetrahydrofolate reductase (MTHFR) gene in prenatally diagnosed neural tube defects (NTD) cases and controls. In contrast to previous reports, we found the same distribution in fetuses with NTD and controls, which suggests that the MTHFR C677T mutation cannot be regarded as a genetic risk factor for NTD.

Abnormal FGFR 3 expression in cartilage of thanatophoric dysplasia fetuses

Thanatophoric dysplasia (TD), the commonest lethal skeletal dysplasia in humans, is accounted for by recurrent mutations in the fibroblast growth factor receptor 3 gene (FGFR 3), causing its constitutive activation in vitro. Taking advantage of medical abortion of 18 TD fetuses, cartilage sections were studied for FGFR 3 gene expression by in situ hybridization and immunohistochemistry. Specific antibodies revealed high amounts of FGFR 3 in cartilage of TD fetuses with no increased level of the corresponding mRNA. The specific signal was mainly detected in the nucleus of proliferative and hypertrophic chondrocytes. Based on this observation and the abnormal expression of collagen type X in hypertrophic TD chondrocytes, we suggest that constitutive activation of the receptor through formation of a stable dimer increases its stability and promotes its translocation into the nucleus, where it might interfere with terminal chondrocyte differentiation.

Undersulfation of cartilage proteoglycans ex vivo and increased contribution of amino acid sulfur to sulfation in vitro in McAlister dysplasia/atelosteogenesis type 2

Mutations in the diastrophic dysplasia sulfate transporter gene cause a family of chondrodysplasias including, in order of increasing severity, diastrophic dysplasia, atelosteogenesis type 2 and achondrogenesis type 1B. McAlister dysplasia is a lethal chondrodysplasia considered on the basis of minor radiographic features to be a disorder different from atelosteogenesis type 2. Here, we demonstrate that McAlister dysplasia arises from mutations in the diastrophic dysplasia sulfate transporter gene and that this disorder essentially coincides on molecular and biochemical grounds with atelosteogenesis type 2. The fetus affected by McAlister dysplasia we have studied is a compound heterozygote for mutations leading to R279W and N425D substitutions in the diastrophic dysplasia sulfate transporter. Proteoglycan sulfation was studied in epiphyseal cartilage and in chondrocyte cultures of the patient by high performance liquid chromatography of chondrotinase digested proteoglycans; a high amount of non-sulfated disaccharide was observed as a consequence of the alteration of the transporter function caused by the mutations. However, sulfated disaccharides were detectable even if in low amounts, both in cultured cells and tissue. Functional impairment of the sulfate transporter was demonstrated in vitro by reduced incorporation of [35S]sulfate relative to [3H]glucosamine in proteoglycans synthesized by chondrocytes and by sulfate-uptake assays in fibroblasts. Parallel in vitro studies in a patient with achondrogenesis 1B indicated that the severity of the clinical phenotype seems to be correlated to the residual activity of the sulfate transporter. The capacity of fibroblasts to use cysteine as an alternative source of sulfate was evaluated by double-labeling experiments. Relative incorporation of [35S]cysteine-derived sulfate in the glycosaminoglycan chains was increased in the patient's cells, indicating that, in vitro, the catabolism of sulfur-containing amino acids can partially compensate for intracellular sulfate deficiency. Residual sulfation observed in proteoglycans extracted from cartilage suggests that this mechanism may be operating also in vivo.

[Detection of chromosome anomalies using in situ hybridization on fetal tissue sections]

The use of in situ hybridization to detect and characterize chromosome anomalies on cytogenetic preparations is now largely applied in clinical laboratories. Its use in embryofetopathology on formalin-fixed and paraffin-embedded tissues, when an aneuploid condition is suspected but a routine chromosomal analysis is not possible was assessed in the present study. Control values of hybridization signals obtained after different enzymatic digestion protocols have been established on normal fetal tissues. Tissue conservation and fetal age as well as other parameters have also been analysed. A successful hybridization has been achieved in most cases. Failure of hybridization was observed in specimens associated with extensive tissular lysis. In conclusion, the application of in situ hybridization on fetal tissues is very useful to detect chromosome anomalies in embryofetopathology.

Familial Blomstrand chondrodysplasia with advanced skeletal maturation: further delineation

We report on two sibs with a rare lethal chondrodysplasia born to a non-consanguineous couple. The hallmarks of this affection, also called Blomstrand chondrodysplasia, are short limbs, polyhydramnios, hydrops fetalis, facial anomalies, increased bone density, and a remarkable advance in skeletal maturation. We describe the radiologic and pathologic manifestations in these two cases. This recurrence affecting a male and a female fetus, born to the same couple, suggests autosomal recessive inheritance.

Tracheal obstruction in experimental diaphragmatic hernia: an endoscopic approach in the fetal lamb

Congenital diaphragmatic hernia (CDH) is associated with a neonatal mortality of up to 50 per cent resulting from pulmonary hypoplasia. Experimental ligation of the trachea increases pulmonary growth in fetuses with experimental diaphragmatic hernia (EDH). To provide a potentially reversible tracheal occlusion (TO) using a minimally invasive procedure, we designed the endoscopic placement of a latex tracheal balloon in fetal lambs with EDH. Following surgical creation of a left EDH at 85 days' gestation, endoscopic occlusion of the fetal trachea was performed at 120 days. The fetuses were retrieved at 139 days. The procedure was successful in 5/11 attempts, resulting in liveborns in which the balloon occluded the trachea completely with expanded lungs and reduction of the herniated viscera into the abdomen. These cases were compared with five cases of EDH without TO and six controls. In the TO group, the lung weight was significantly greater but the radial alveolar count, DNA content, and protein content were similar to normal controls. All lung growth parameters were greater in the TO than in the EDH group. Occlusion of the trachea using an endoscopic technique could provide a useful alternative to open fetal surgery in fetuses with CDH.

Fetal serum interferon-alpha suggests viral infection as the aetiology of unexplained lateral cerebral ventriculomegaly

We assayed fetal serum interferon-alpha (IFNA), a cytokine produced by leukocytes as a response to viral infection, in a series of 59 consecutive cases of ventriculomegaly diagnosed in utero and in 89 controls. Results were correlated with other findings including karyotype, maternal-fetal screening for serum antibodies to specific infectious pathogens, viral cultures of amniotic fluid, and neuropathological examination or postnatal follow-up. Fetal serum IFNA assay was negative in the five ventriculomegalies associated with a genetic anomaly and positive in the three cases with documented cytomegalovirus infections. In addition, fetal serum IFNA was detected significantly more often in the cases of ventriculomegaly with unexplained pathogenesis (15/51, 29.4 per cent) than in controls (1/89, 1.1 per cent). Detection of IFNA suggestive of viral infection in fetuses with otherwise unexplained ventriculomegaly underscores the need for more extensive viral screening in such cases.

Undersulfation of proteoglycans synthesized by chondrocytes from a patient with achondrogenesis type 1B homozygous for an L483P substitution in the diastrophic dysplasia sulfate transporter

Achondrogenesis type 1B is an autosomal recessive, lethal chondrodysplasia caused by mutations in the gene encoding a sulfate/chloride antiporter of the cell membrane (Superti-Furga, A., Hästbacka, J., Wilcox, W. R., Cohn, D. H., van der Harten, J. J., Rossi, A., Blau, N., Rimoin, D. L., Steinmann, B., Lander, E. S., and Gitzelmann, R.(1996) Nat. Genet. 12, 100-102). To ascertain the consequences of the sulfate transport defect on proteoglycan synthesis, we studied the structure and sulfation of proteoglycans in cartilage tissue and in fibroblast and chondrocyte cultures from a fetus with achondrogenesis 1B. Proteoglycans extracted from epiphyseal cartilage and separated on agarose gels migrated more slowly than controls and stained poorly with alcian blue. The patient's cultured cells showed reduced incorporation of [35S]sulfate relative to [3H]glucosamine, impaired uptake of sulfate, and higher resistance to chromate toxicity compared to control cells. Epiphyseal chondrocytes cultured in alginate beads synthesized proteoglycans of normal molecular size as judged by gel filtration chromatography, but undersulfated as judged by ion exchange chromatography and by the amount of nonsulfated disaccharide. High performance liquid chromatography analysis of chondroitinase-digested proteoglycans showed that sulfated disaccharides were present, although in reduced amounts, indicating that at least in vitro, other sources of sulfate can partially compensate for sulfate deficiency. A t1475c transition causing a L483P substitution in the eleventh transmembrane domain of the sulfate/chloride antiporter was present on both alleles in the patient who was the product of a consanguineous marriage. The results indicate that the defect of sulfate transport is expressed in both chondrocytes and fibroblasts and results in the synthesis of proteoglycans bearing glycosaminoglycan chains which are poorly sulfated but of normal length.

Aortico-left ventricular tunnel in fetuses and infants

BACKGROUND

Aortico-left ventricular tunnel is a rare congenital abnormal communication between the aorta and the left ventricle presenting in early childhood as aortic regurgitation and cardiac failure. This condition has rarely been reported in fetuses. Operation is the only treatment, and postoperative aortic incompetence could be related to the age or the type of repair.

METHODS

We conducted a retrospective, two-institution review, from 1983 to 1995, of aortico-left ventricular tunnel diagnosed in utero and before 6 months of age.

RESULTS

Three cases of aortico-left ventricular tunnel were diagnosed in utero by Doppler echocardiography between 22 and 24 weeks' gestation. Prenatal aortico-left ventricular tunnel was associated with severe left ventricular dysfunction, aortic valve anomalies, and fetal hydrops. One death occurred in utero and one immediately after birth, and in 1 case pregnancy was interrupted. In these 3 cases the diagnosis was confirmed by autopsy. Three neonates and 2 infants had the diagnosis of aortico-left ventricular tunnel made after birth and underwent successful surgical repair. At short and midterm follow-up all patients are alive and aortic valve regurgitation is absent or trivial.

CONCLUSIONS

This series shows that aortico-left ventricular tunnel covers an anatomic spectrum of lesions. Cases diagnosed in utero by Doppler echocardiography are characterized by severe ventricular dysfunction, associated aortic valve lesions, and poor outcome. Postnatal cases represent the more favorable end of the spectrum, with no associated lesions, and can be repaired without mortality and with good functional results.