Deletion 15q24-26 in prenatally detected diaphragmatic hernia: increasing evidence of a candidate region for diaphragmatic development

CHD2-Related CNS Pathologies

Epileptic encephalopathies (EE) are severe epilepsy syndromes characterized by multiple seizure types, developmental delay and even regression. This class of disorders are increasingly being identified as resulting from de novo genetic mutations including many identified mutations in the family of chromodomain helicase DNA binding (CHD) proteins. In particular, several de novo pathogenic mutations have been identified in the gene encoding chromodomain helicase DNA binding protein 2 (CHD2), a member of the sucrose nonfermenting (SNF-2) protein family of epigenetic regulators. These mutations in the CHD2 gene are causative of early onset epileptic encephalopathy, abnormal brain function, and intellectual disability. Our understanding of the mechanisms by which modification or loss of CHD2 cause this condition remains poorly understood. Here, we review what is known and still to be elucidated as regards the structure and function of CHD2 and how its dysregulation leads to a highly variable range of phenotypic presentations.

Array Characterization of Prenatally Diagnosed 15q26 Microdeletion and 2q37.1 Duplication: Report of a New Case with Multicystic Kidneys and Review of the Literature

We report on a molecular cytogenetic characterization of 15q26 deletion and 2q37.1 duplication in a fetus presenting with intrauterine growth restriction (IUGR), diaphragmatic hernia, multicystic kidneys, left kidney pyelectasis, and clubfeet. A terminal 15q26 deletion and a terminal 2q duplication of at least 10 and 9 Mb, respectively, derived from a maternal translocation, were found. The 15q26 deletion represents a contiguous gene deletion syndrome mainly characterized by IUGR, congenital diaphragmatic hernia, and less frequently kidney defects. This deletion encompasses the IGF1R and COUPTF2 genes, known to lead to fetal growth retardation syndrome. However, kidney malformations are less well known in such conditions, and to the best of our knowledge, no candidate gene has been proposed to date. Here, we review the literature of the 15q26 deletion syndrome and suggest that hypoplastic and multicystic kidneys, the most commonly observed anomalies in this condition, should be considered in the prenatal diagnosis setting. Based on COUPTF2 protein function, we hypothesize that its haploinsufficiency might be responsible for the renal pathology.

Pre- and Postnatal Analysis of Chromosome 15q26.1 and 8p23.1 Deletions in Congenital Diaphragmatic Hernia

Congenital diaphragmatic hernia (CDH) is defined as a protrusion of abdominal content into the thoracic cavity through an abnormal opening in the diaphragm present at birth. It is a common birth defect with high mortality and morbidity. Submicroscopic deletions of 15q26.1 and 8p23.1 have been reported in several cases of CDH. We studied a total of 17 cases with CDH in pre- and postnatal samples using FISH probes. Deletion 15q26.1 was seen in 1/17 prenatal samples. There was no deletion for 8p23.1 in all the samples analyzed. CDH has a genetic etiology, and deletion 15q26.1 increases the risk of CDH. Deletion 15q26.1 in a fetus with CDH is a predictor of poor prognosis. This deletion is also seen in a phenotype similar to Fryns syndrome. CDH identified pre- or postnatally should be investigated further to exclude a 15q26.1 deletion and enable appropriate parental counseling.

Prenatal diagnosis of a fetus with ring chromosomal 15 by two- and three-dimensional ultrasonography

We report on a prenatal diagnosis of ring chromosome 15 in a fetus with left congenital diaphragmatic hernia (CDH) and severe intrauterine growth restriction (IUGR). A 31-year-old woman, gravida 2 para 1, was referred because of increased nuchal translucency at gestational age of 13 weeks. Comprehensive fetal ultrasound examination was performed at 19 weeks revealing an early onset IUGR, left CDH with liver herniation, and hypoplastic nasal bone. Three-dimensional ultrasound (rendering mode) showed low set ears and depressed nasal bridge. Amniocentesis was performed with a result of a 46,XX,r(15) fetus after a cytogenetic study. A 1,430 g infant (less than third percentile) was born at 36 weeks. The infant presented with respiratory failure and died at 2 h of life. Postnatal karyotype from the umbilical cord confirmed the diagnosis of 15-ring chromosome. We described the main prenatal 2D- and 3D-ultrasound findings associated with ring chromosome 15. The interest in reporting the present case is that CDH can be associated with the diagnosis of 15-ring chromosome because the critical location of the normal diaphragm development is at chromosome 15q26.1-q26.2.

COUP-TFs and eye development

Recent studies reveal that COUP-TF genes are essential for neural development, cardiovascular development, energy metabolism and adipogenesis, as well as for organogenesis of multiple systems. In this review, we mainly describe the COUP-TF genes, molecular mechanisms of COUP-TF action, and their crucial functions in the morphogenesis of the murine eye. Mutations of COUP-TF genes lead to the congenital coloboma and/or optic atrophy in both mouse and human, indicating that the study on COUP-TFs and the eye will benefit our understanding of the etiology of human ocular diseases. This article is part of a Special Issue entitled: Nuclear receptors in animal development.

Role of copy number variants in structural birth defects

BACKGROUND AND OBJECTIVE

Human genomes include copy number variants (CNVs), defined as regions with DNA gains or losses. Pathologic CNVs, which are larger and often occur de novo, are increasingly associated with disease. Given advances in genetic testing, namely microarray-based comparative genomic hybridization and single nucleotide polymorphism arrays, previously unidentified genotypic aberrations can now be correlated with phenotypic anomalies. The objective of this study was to conduct a nonsystematic literature review to document the role of CNVs as they relate to isolated structural anomalies of the craniofacial, respiratory, renal, and cardiac systems.

METHODS

All full-length articles in the PubMed database through May 2011 that discussed CNVs and isolated structural defects of the craniofacial, respiratory, renal, and cardiac systems were considered. Search terms queried include CNV, copy number variation, array comparative genomic hybridization, birth defects, craniofacial defects, respiratory defects, renal defects, and congenital heart disease. Reports published in languages other than English and articles regarding CNVs and neurocognitive deficits were not considered.

RESULTS

Evidence supports that putatively pathogenic CNVs occur at an increased frequency in patients with isolated structural birth defects and implicate specific regions of the genome. Through CNV detection, advances have been made in identifying genes and specific loci that underlie isolated birth defects.

CONCLUSIONS

Although limited studies have been published, the promising evidence reviewed here warrants the continued investigation of CNVs in children with isolated structural birth defects. Patient care and genetic counseling stand to improve through a better understanding of CNVs and their effect on disease phenotype.

Congenital diaphragmatic hernia

Congenital Diaphragmatic Hernia (CDH) is defined by the presence of an orifice in the diaphragm, more often left and posterolateral that permits the herniation of abdominal contents into the thorax. The lungs are hypoplastic and have abnormal vessels that cause respiratory insufficiency and persistent pulmonary hypertension with high mortality. About one third of cases have cardiovascular malformations and lesser proportions have skeletal, neural, genitourinary, gastrointestinal or other defects. CDH can be a component of Pallister-Killian, Fryns, Ghersoni-Baruch, WAGR, Denys-Drash, Brachman-De Lange, Donnai-Barrow or Wolf-Hirschhorn syndromes. Some chromosomal anomalies involve CDH as well. The incidence is < 5 in 10,000 live-births. The etiology is unknown although clinical, genetic and experimental evidence points to disturbances in the retinoid-signaling pathway during organogenesis. Antenatal diagnosis is often made and this allows prenatal management (open correction of the hernia in the past and reversible fetoscopic tracheal obstruction nowadays) that may be indicated in cases with severe lung hypoplasia and grim prognosis. Treatment after birth requires all the refinements of critical care including extracorporeal membrane oxygenation prior to surgical correction. The best hospital series report 80% survival but it remains around 50% in population-based studies. Chronic respiratory tract disease, neurodevelopmental problems, neurosensorial hearing loss and gastroesophageal reflux are common problems in survivors. Much more research on several aspects of this severe condition is warranted.

Coup d'Etat: an orphan takes control

Chicken ovalbumin upstream promoter transcription factors (COUP-TFs) belong to the steroid/thyroid hormone receptor superfamily. Cloning of their cDNAs demonstrated the existence of two distinct but related genes: COUP-TFI (EAR-3, NR2F1) and COUP-TFII (ARP-1, NR2F2). They are referred to as orphan receptors because ligands for COUP-TFs have yet to be identified. Since 1998, extensive studies have demonstrated their physiological importance in cell-fate specification, organogenesis, angiogenesis, and metabolism, as well as a variety of diseases. In this article, we will comprehensively review the biological functions of COUP-TFII and its underlying mechanism in various developmental processes and diseases. In addition, we will briefly summarize some of the current findings of COUP-TFI.

The Transcriptional Control of Lymphatic Vascular Development

More than 100 years ago, Florence Sabin suggested that lymphatic vessels develop by sprouting from preexisting blood vessels, but it is only over the past decade that the molecular mechanisms underpinning lymphatic vascular development have begun to be elucidated. Genetic manipulations in mice have identified a transcriptional hub comprised of Prox1, CoupTFII, and Sox18 that is essential for lymphatic endothelial cell fate specification. Recent work has identified a number of additional transcription factors that regulate later stages of lymphatic vessel differentiation and maturation. This review highlights recent advances in our understanding of the transcriptional control of lymphatic vascular development and reflects on efforts to better understand the activities of transcriptional networks during this discrete developmental process. Finally, we highlight the transcription factors associated with human lymphatic vascular disorders, demonstrating the importance of understanding how the activity of these key molecules is regulated, with a view toward the development of innovative therapeutic avenues.

Early onset myoclonic epilepsy and 15q26 microdeletion: observation of the first case

The authors report the study of a 30-month-old girl with refractory myoclonic epilepsy associated with mental retardation, growth delay, peculiar facial appearance, and minor physical anomalies. Extensive genetic studies were performed, including an array-based comparative genomic hybridization (array-CGH) that showed a cryptic interstitial deletion of 15q (5 Mb) affecting the 15q26.1-26.2 region. Partial deletions of the long arm of chromosome 15, including the 15q26 region, were observed in syndromic associations that typically include congenital diaphragmatic hernia, but neurologic features were poorly described and epileptic seizures were never reported. Our findings suggest that genes for seizures could be included in the 15q26.1q26.2 deletion interval.

Drayer's syndrome of mental retardation, microcephaly, short stature and absent phalanges is caused by a recurrent deletion of chromosome 15(q26.2-->qter)

We reevaluated a unique family with two sibs who had a presumed autosomal recessively inherited syndrome characterized by mental retardation, microcephaly, short stature and absent phalanges. This family was originally described by Drayer et al. in 1977. Using modern molecular techniques, we demonstrated that the syndrome is caused by the recurrence of an apparently de novo 15qter deletion of 5.8 Mb. Analysis of polymorphic markers revealed that the deletion was of maternal origin in both cases, indicating germline mosaicism in the clinically unaffected mother. This study demonstrates the possibility of parental mosaicism and the risk of recurrence in sibs for terminal subtelomeric deletions.

Disruption of chromodomain helicase DNA binding protein 2 (CHD2) causes scoliosis

Herein we characterize an apparently balanced de novo translocation, t(X;15)(p22.2;q26.1)dn, in a female patient with scoliosis, hirsutism, learning problems, and developmental delay (DGAP025). Other clinical findings include a high-arched palate, 2-3 syndactyly of the toes, and mildly elevated serum testosterone. No known or predicted genes are disrupted by the Xp22.2 breakpoint. The 15q26.1 breakpoint disrupts chromodomain helicase DNA binding protein 2 (CHD2). Another member of the chromatin-remodeling gene family, CHD7, has been associated with a defined constellation of congenital anomalies known as coloboma, heart anomaly, choanal atresia, mental retardation, genital and ear anomalies syndrome (CHARGE) and idiopathic scoliosis. Monosomy of 15q26 also has been associated with a spectrum of congenital abnormalities and growth retardation that overlaps with those of DGAP025. To provide a biological correlate, we characterized a mutant mouse model with Chd2 disruption that is associated with embryonic and perinatal lethality. Expression analysis indicated that Chd2 is expressed in the heart, forebrain, extremities, facial and dorsal regions during specific times of embryonic development. Chd2(+/m) mice showed pronounced lordokyphosis, reduced body fat, postnatal runting, and growth retardation. These data suggest that haploinsufficiency for CHD2 could result in a complex of abnormal human phenotypes that includes scoliosis and possibly features similar to CHARGE syndrome.

Gene expression in the developing diaphragm: significance for congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a frequently occurring birth defect and a source of potentially fatal neonatal respiratory distress. Recently, through the application of detailed karyotyping methods, several CDH-critical regions within the human genome have been identified. These regions typically contain several genes. Here we focused on genes from 15q26, the best-characterized CDH-critical region, as well as FOG2 and GATA4, genes singled out from CDH-critical regions at 8q22-8q23 and 8p23.1, respectively. We tested the hypothesis that these putative CDH-related genes are expressed within the developing diaphragm at the time of the hypothesized initial defect. Our results show that 15q26 contains a cluster of genes that are expressed in the developing rodent diaphragm, consistent with an association between deletions in this region and CDH. We then examined the protein expression pattern of positively identified genes within the developing diaphragm. Two major themes emerged. First, those factors strongly associated with CDH are expressed only in the nonmuscular, mesenchymal component of the diaphragm, supporting the hypothesis that CDH has its origins in a mesenchymal defect. Second, these factors are all coexpressed in the same cells. This suggests that cases of CDH with unique genetic etiology may lead to a common defect in these cells and supports the hypothesis that these factors may be members of a common pathway. This study is the first to provide a detailed examination of how genes associated with CDH are expressed in the developing diaphragm and provides an important foundation for understanding how the deletion of specific genes may contribute to abnormal diaphragm formation.

Congenital diaphragmatic hernia (CDH) etiology as revealed by pathway genetics

Congenital diaphragmatic hernia (CDH) is a common birth defect with high mortality and morbidity. Two hundred seventy CDH patients were ascertained, carefully phenotyped, and classified as isolated (diaphragm defects alone) or complex (with additional anomalies) cases. We established different strategies to reveal CDH-critical chromosome loci and genes in humans. Candidate genes for sequencing analyses were selected from CDH animal models, genetic intervals of recurrent chromosomal aberration in humans, such as 15q26.1-q26.2 or 1q41-q42.12, as well as genes in the retinoic acid and related pathways and those known to be involved in embryonic lung development. For instance, FOG2, GATA4, and COUP-TFII are all needed for both normal diaphragm and lung development and are likely all in the same genetic and molecular pathway. Linkage analysis was applied first in a large inbred family and then in four multiplex families with Donnai-Barrow syndrome (DBS) associated with CDH. 10K SNP chip and microsatellite markers revealed a DBS locus on chromosome 2q23.3-q31.1. We applied array-based comparative genomic hybridization (aCGH) techniques to over 30, mostly complex, CDH patients and found a de novo microdeletion in a patient with Fryns syndrome related to CDH. Fluorescence in situ hybridization (FISH) and multiplex ligation-dependent probe amplification (MLPA) techniques allowed us to further define the deletion interval. Our aim is to identify genetic intervals and, in those, to prioritize genes that might reveal molecular pathways, mutations in any step of which, might contribute to the same phenotype. More important, the elucidation of pathways may ultimately provide clues to treatment strategies.

Molecular characterization of a ring chromosome 15 in a fetus with intra uterine growth retardation and diaphragmatic hernia

OBJECTIVE

To improve the phenotype-genotype correlation in terminal 15q deletions and ring chromosome 15 syndrome.

METHODS

Echographic examination of fetus. R-banded chromosome and FISH analysis on cultured amniocytes. Microsatellite analysis to determine parental origin of the ring chromosome 15. Fetal autopsy.

RESULTS

We report a new case of prenatal diagnosis of congenital diaphragmatic hernia and intrauterine growth retardation in a fetus with ring chromosome 15 involving 15q26.1-qter deletion.

CONCLUSION

This case support the evidence that the region 15q26.3 is implicated in intrauterine growth retardation and suggests that the 15q critical region implicated in congenital diaphragmatic hernia is localized in 15q26.1-q26.2.

Overview of epidemiology, genetics, birth defects, and chromosome abnormalities associated with CDH

Congenital diaphragmatic hernia (CDH) is a common and well-studied birth defect. The etiology of most cases remains unknown but increasing evidence points to genetic causation. The data supporting genetic etiologies which are detailed below include the association of CDH with recurring chromosome abnormalities, the existence of CDH-multiplex families, and the co-occurrence of CDH with additional congenital malformations.

Genetic factors in congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a relatively common birth defect associated with high mortality and morbidity. Although the exact etiology of most cases of CDH remains unknown, there is a growing body of evidence that genetic factors play an important role in the development of CDH. In this review, we examine key findings that are likely to form the basis for future research in this field. Specific topics include a short overview of normal and abnormal diaphragm development, a discussion of syndromic forms of CDH, a detailed review of chromosomal regions recurrently altered in CDH, a description of the retinoid hypothesis of CDH, and evidence of the roles of specific genes in the development of CDH.

Experiences in the Perinatal Management of Congenital Diaphragmatic Hernia during the Last 15 Years in a Tertiary Referral Institute

OBJECTIVE

Review of cases of perinatally diagnosed congenital diaphragmatic hernias with special regard to time of diagnosis, organs herniated into the thorax, associated malformations, and outcomes.

METHODS

We analyzed the data of 106 cases between July 1, 1990, and June 30, 2005. The observation period was analyzed in two parts.

RESULTS

Prenatal ultrasound was performed in 89.6% (95/106) of the cases. 51.7% (46/89) of the pre- and postnatally verified congenital diaphragmatic hernia cases were diagnosed before the 24th week of gestation. 11% (11/100) of the hernias were identified postnatally. 71% (71/100) of the cases were associated with other malformations. The hernia was on the left side in 86% (86/100) and bilateral in 5% (5/100) of the cases. Between 1990 and 1997, the proportion of right-sided hernias was 4.3% (2/46), while during the second period it was 13% (7/54). 27.5% (14/51) of the newborns survived the perinatal period. The survival rate of the newborns delivered by caesarean section was three times higher than that of infants delivered vaginally. In the latter group, the rate of premature deliveries was considerably higher. The pregnancy was terminated in 45% (40/89) of the cases. 15% (6/40) of the terminated cases were isolated. Intrauterine or intrapartum deaths occurred in 5.6% (5/89) of the prenatally diagnosed cases. Simultaneous thoracic herniation of liver, spleen, or stomach decreased the survival rate. In these cases, the discharge rate was between 6 and 22%.

CONCLUSIONS

According to the analysis of 15-year data, the herniated organs, multiple malformations, as well as the mode of delivery influence the survival in a large number of cases. Early diagnosis predicts a large hernia, a higher malformation rate, and a less favourable prognosis.

Prenatal detection and outcome of congenital diaphragmatic hernia (CDH) associated with deletion of chromosome 15q26: Two patients and review of the literature

Congenital diaphragmatic hernia (CDH) is a severe birth defect characterized by a defect in the diaphragm with pulmonary hypoplasia and postnatal pulmonary hypertension. Approximately 50% of CDH cases are associated with other non-pulmonary congenital anomalies (so called non-isolated CDH) and in 5-10% of cases there is a chromosomal etiology. The majority of CDH cases are detected prenatally. In some cases prenatal chromosome analysis reveals a causative chromosomal anomaly, most often aneuploidy. Deletion of 15q26 is the most frequently described structural chromosomal aberration in patients with non-isolated CDH. In this paper we report on two patients with a deletion of 15q26 and phenotypes similar to other patients with CDH caused by 15q26 deletions. This phenotype consists of intra-uterine growth retardation, left-sided CDH, cardiac anomalies and characteristic facial features, similar to those seen in Fryns syndrome. We propose that when this combination of birth defects is identified, either pre- or postnatally, further investigations to confirm or exclude a deletion of 15q26 are indicated, since the diagnosis of this deletion will have major consequences for the prognosis and, therefore, can affect decision making.

Array comparative genomic hybridization in patients with congenital diaphragmatic hernia: mapping of four CDH-critical regions and sequencing of candidate genes at 15q26.1–15q26.2

Congenital diaphragmatic hernia (CDH) is a common birth defect with a high mortality and morbidity. There have been few studies that have assessed copy number changes in CDH. We present array comparative genomic hybridization data for 29 CDH patients to identify and map chromosome aberrations in this disease. Three patients with 15q26.1-15q26.2 deletions had heterogeneous breakpoints that overlapped with the critical 4 Mb region previously delineated for CDH, confirming 15q26.1-15q26.2 as a critical region for CDH. The three other most compelling CDH-critical regions for genomic deletions based on these data and a literature review are located at chromosomes 8p23.1, 4p16.3-4pter, and 1q41-1q42.1. Based on these recurrent deletions at 15q26.1-15q26.2, we hypothesized that loss-of-function mutations in a gene or genes from this region could cause CDH and sequenced six candidate genes from this region in more than 100 patients with CDH. For three of these genes (CHD2, ARRDC4, and RGMA), we identified missense changes and that were not identified in normal controls; however, none of these alterations appeared unambiguously causal with CDH. These data suggest that CDH caused by chromosome deletions at 15q26.2 may arise because of a contiguous gene deletion syndrome or may have a multifactorial etiology. In addition, there is evidence for substantial genetic heterogeneity in CDH and diaphragmatic hernias can be non-penetrant in patients who have deletions involving CDH-critical regions.

Prenatal diagnosis ofde novo deletions of 8p23.1 or 15q26.1 in two fetuses with diaphragmatic hernia and congenital heart defects

OBJECTIVE

To show the importance of using high-resolution chromosome analysis and FISH-technique for finding subtle chromosomal lesions in prenatal diagnosis specially when there are abnormal ultrasound findings.

METHODS

Ecographic examination of the fetus. GTG banded chromosome and FISH analysis using subtelomeric probes on amniocytes.

RESULTS

We report two prenatal cases with congenital diaphragmatic hernia (CDH) and congenital heart defects (CHDs) with different deletions confirmed by FISH: del(8)(p23.1p23.1) and del(15)(q26.1).

CONCLUSION

These cases support the evidence that the regions 15q26.1 and 8p23.1 may play an important role in the development of the diaphragm. A deletion 8p23.1 or 15q26.1 should be considered whenever a CDH and/or a cardiac abnormality are detected on ultrasound.

Associated malformations in congenital diaphragmatic hernia cases in the last 15 years in a tertiary referral institute

This is a review of cases of perinatally diagnosed congenital diaphragmatic hernia (CDH) with associated malformations with regard to time of diagnosis, side of hernia, associated malformations, and outcome. The authors analyzed the data of CDH cases with associated malformations from records of the I. Department of Obstetrics and Gynecology, Semmelweis University Faculty of Medicine, Budapest, between July 1, 1990 and June 30, 2005. The observed period was analyzed in two parts. The pre- and postnatal examinations verified CDH in 100 cases, 71% of which were associated with other malformations. In 52% (37/71) CDH was diagnosed before the 24th week of gestation. The rate of early diagnosed cases doubled in the second period. Ten percent (7/71) of cases were verified postnatally. Between 1990 and 1997, the percentage of right-sided hernia was 6% (2/34) while in the second period it was 19% (7/37). The association with cardiovascular, chest, and craniofacial anomalies doubled in the second period, while association of central nervous system anomalies halved. Chromosome anomalies were verified in four cases. Pregnancy was terminated in 53% (34/64) and 13% (4/30) of newborn infants survived the perinatal period. Intrauterine or intrapartum death occurred in 8% (5/64) of cases. The prevalence of cardiovascular, pulmonary, and craniofacial anomalies doubled, while that of central nervous system malformations decreased. The prevalence of other associated malformations has not changed significantly between the two periods. The improvement of technical facilities and accumulated experience make it possible to identify a higher number of associated malformations before the 24th week of gestation.

Mouse lacking COUP-TFII as an animal model of Bochdalek-type congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH), a life-threatening anomaly, is a major cause of pediatric mortality. Although the disease was described >350 years ago, the etiology of CDH is poorly understood. Here, we show that tissue-specific null mutants of COUP-TFII exhibit Bochdalek-type CDH, the most common form of CDH. COUP-TFII, a member of orphan nuclear receptors, is expressed in regions critical for the formation of the diaphragm during embryonic development. Ablation of COUP-TFII in the foregut mesenchyme, including the posthepatic mesenchymal plate (PHMP), results in the malformation of the diaphragm and the failure of appropriate attachment of the PHMP to the body wall. Thus, both the stomach and liver enter the thoracic cavity, leading to lung hypoplasia and neonatal death. Recently a minimally deleted region for CDH has been identified on chromosome 15q26.1-26.2 by CGH array and FISH analysis. COUP-TFII is one of the four known genes residing within this critical region. Our finding suggests that COUP-TFII is a likely contributor to the formation of CDH in individuals with 15q deletions, and it may also be a potential contributor to some other Bochdalek-type of CDH.

Infants with Bochdalek diaphragmatic hernia: sibling precurrence and monozygotic twin discordance in a hospital-based malformation surveillance program

Congenital diaphragmatic hernia (CDH) is a common and often devastating birth defect. In order to learn more about possible genetic causes, we reviewed and classified 203 cases of the Bochdalek hernia type identified through the Brigham and Women's Hospital (BWH) Active Malformation Surveillance Program over a 28-year period. Phenotypically, 55% of the cases had isolated CDH, and 45% had complex CDH defined as CDH in association with additional major malformations or as part of a syndrome. When classified according to likely etiology, 17% had a Recognized Genetic etiology for their CDH, while the remaining 83% had No Apparent Genetic etiology. Detailed analysis using this largest cohort of consecutively collected cases of CDH showed low precurrence among siblings. Additionally, there was no concordance for CDH among five monozygotic twin pairs. These findings, in conjunction with previous reports of de novo dominant mutations in patients with CDH, suggest that new mutations may be an important mechanism responsible for CDH. The twin data also raise the possibility that epigenetic abnormalities contribute to the development of CDH.

Prenatal diagnosis of congenital diaphragmatic hernia in a fetus with 46,XY/46,X,-Y,+der(Y)t(Y;1)(q12;q12) mosaicism: a case report

Congenital diaphragmatic hernia (CDH) is often associated with major anomalies and chromosomal abnormalities. Chromosomal abnormalities are usually detected in 9.5% to 34% of fetuses with CDH prenatally diagnosed and the defect has also been reported in association with multiple syndromes such as Pallister-Killian syndrome, Fryns syndrome, Di George syndrome and Apert syndrome. Among the chromosomal abnormalities associated with CDH, trisomy 21, 18, and 13 are most common. Association with complex chromosomal aberrations such as mosaicism has also been reported. However, CDH presented in a fetus with Y-autosome translocation is extremely rare. Herein, we reported a case of fetus with 46,XY/46,X,-Y, +der(Y)t(Y;1)(q12;q12) mosaicism who presented with CDH diagnosed by ultrasonography at 19 weeks' gestation.

The co-occurrence of congenital diaphragmatic hernia, esophageal atresia/tracheoesophageal fistula, and lung hypoplasia

BACKGROUND

Two severe birth defects, congenital diaphragmatic hernia (CDH) and esophageal atresia (EA) with or without tracheoesophageal fistula (TEF), have traditionally been analyzed separately in epidemiological studies. Lung hypoplasia (LH), part of the CDH spectrum, is not usually associated with EA/TEF, yet both are foregut malformations.

METHODS

We conducted an epidemiological study of two combinations of the defects in the population of 3,318,966 live births and stillbirths monitored from 1983 to 1996 by the California Birth Defects Monitoring Program (CBDMP).

RESULTS

A total of 433 cases had a Bochdalek type CDH/LH (0.13 per 1000 births), 893 had EA/TEF (0.27 per 1000 births), and 646 had LH (0.19 per 1000 births). Among them, 18 cases had CDH/LH with EA/TEF (0.005 per 1000 births), and 53 had EA/TEF and LH (0.02 per 1000 births); both prevalences are significantly higher than expected. Sixteen of 17 cases of CDH/LH with EA/TEF, and 34 of 40 cases of EA/TEF with LH were stillborn or died; 72% and 74%, respectively, had an autopsy. The male to female sex ratios were 1.43 and 1.13, respectively. In both groups, infants had similar proportions of additional severe defects, except for genitourinary and anal defects and syndromes/associations, which were more prevalent in the EA/TEF with LH group. We reviewed human studies and experimental animal models for factors reported to cause any combination of the defects.

CONCLUSIONS

Several genetic and environmental factors could affect the significant co-occurrence of the defects. Future studies should include storage of patients' biological materials for DNA analysis, karyotyping, and environmental exposure evaluation.

Congenital diaphragmatic hernia and chromosome 15q26: determination of a candidate region by use of fluorescent in situ hybridization and array-based comparative genomic hybridization

Congenital diaphragmatic hernia (CDH) has an incidence of 1 in 3,000 births and a high mortality rate (33%-58%). Multifactorial inheritance, teratogenic agents, and genetic abnormalities have all been suggested as possible etiologic factors. To define candidate regions for CDH, we analyzed cytogenetic data collected on 200 CDH cases, of which 7% and 5% showed numerical and structural abnormalities, respectively. This study focused on the most frequent structural anomaly found: a deletion on chromosome 15q. We analyzed material from three of our patients and from four previously published patients with CDH and a 15q deletion. By using array-based comparative genomic hybridization and fluorescent in situ hybridization to determine the boundaries of the deletions and by including data from two individuals with terminal 15q deletions but without CDH, we were able to exclude a substantial portion of the telomeric region from the genetic etiology of this disorder. Moreover, one patient with CDH harbored a small interstitial deletion. Together, these findings allowed us to define a minimal deletion region of approximately 5 Mb at chromosome 15q26.1-26.2. The region contains four known genes, of which two--NR2F2 and CHD2--are particularly intriguing gene candidates for CDH.

A patient with a de novo 15q24q26.1 interstitial deletion, developmental delay, mild dysmorphism, and very blue irises

We report on a patient with a de novo 15q24q26.1 interstitial deletion. She presented with developmental delay, behavioral characteristics, and mild dysmorphism with very blue irises. We review the limited literature of interstitial 15q deletions. There was no distinct phenotypic overlap between these two cases in literature and the present patient. Additional reports are necessary in order to establish a possible recognizable deletion 15q24q26.1 phenotype.

A report of three patients with an interstitial deletion of chromosome 15q24

Partial monosomy of the q2 region of chromosome 15 has been infrequently reported. Moreover, interstitial deletions involving 15q22-q24 have been described in only nine patients to date. The phenotype of these reported individuals is subject to the extent of the deletion but typically includes altered muscle tone and significant developmental delays. In addition, eye abnormalities, such as strabismus, microphthalmia, or colobomas, ear abnormalities including cleft earlobe and preauricular tags, and urogenital defects are common features. Congenital heart defects, diaphragmatic hernia, abnormalities of the central nervous system, and skeletal anomalies have been reported but appear to be less frequent clinical manifestations. In this report, we describe three new patients with interstitial deletions involving 15q24, two with cryptic deletions identified by fluorescence in situ hybridization (FISH) with a probe for the PML gene and one with a cytogenetically visible deletion of 15q22.3-q24. The clinical presentation of these individuals is similar to those previously described and includes global developmental delays, hypotonia, and genital abnormalities in the males. The identification of these three cases demonstrates that the above clinical features are associated with a new cytogenetic deletion syndrome. Furthermore, we suggest that FISH analysis with a probe for the PML gene be performed in patients with these physical findings.

Association of Deletions of the Chromosomal Region 15q24-ter and Diaphragmatic Hernia: A New Case and Discussion of the Literature

OBJECTIVE

To provide new insights into how chromosomal aberrations affect fetal development, as well as for the counseling of parents in comparable situations, it is important to characterize and report the genotypes of fetuses with clinical anomalies.

METHODS

Molecular cytogenetic analyses in a fetus with congenital diaphragmatic hernia (CDH).

RESULTS

This report describes the first case of a deletion of the region q26.1-ter on chromosome 15 occurring as a de novo event associated with CDH. A detailed review of the literature provides further evidence of a functional association between deletions within the chromosomal region 15q24-ter and the development of CDH.

CONCLUSIONS

The obtained data argue that detection of such a deletion in the region 15q24-ter associated with CDH likely predicts a poor prognosis. This report highlights the importance of giving special diagnostic attention to the chromosomal region 15q24-ter when prenatal ultrasound examination provides evidence of a CDH and warrants further research to identify genetic elements within the chromosomal region 15q24-ter related to the development of diaphragmatic hernia.

Postmortem findings and clinicopathological correlation in congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a severe life-threatening disease, with an incidence of 3 per 10,000 births, that can occur as an isolated defect or in combination with other congenital anomalies. We reviewed the clinical and autopsy reports of 39 subjects with CDH that were autopsied between 1988 and 2001 to determine whether autopsy had an additional value in the detection of malformations in patients with CDH. We compared the clinical data (including echographic results in some patients) concerning congenital anomalies with the autopsy results. Before autopsy, 6 structural cardiac defects, 3 anomalies of the urogenital system, and 3 anomalies of the digestive tract were observed in 10 patients (clinical and echographic results). However, with postmortem examination, only 4 structural cardiac defects were confirmed, 2 cases showed another cardiac anomaly, and 7 new cardiac defects were found. In the urogenital system, 1 anomaly was confirmed, 1 was not confirmed, and 1 showed another malformation. In addition, in 7 patients new urogenital malformations were found after autopsy. In the digestive tract, all 3 malformations were confirmed, but we found 3 new malformations after postmortem examination. All clinically established dysmorphic features and anomalies of the skeletal system and central nervous system were confirmed by autopsy, and no additional malformations were found. We concluded that postmortem examination has an important additional role in the detection of structural cardiac defects and malformations of the urogenital system and digestive tract in children with CDH.

Congenital diaphragmatic hernia: is 15q26.1-26.2 a candidate locus?

Congenital diaphragmatic hernia is a developmental abnormality due to failure of the normal formation of the diaphragm. While the majority of cases are idiopathic, chromosomal abnormalities have been implicated in approximately 15% of cases. Several recent series have suggested that 15q24-26 is critical in normal development of the diaphragm. We present a patient with a karyotype of 46, XX, del (15)(q26.1) born with a diaphragmatic hernia, coarctation of the aorta, and dysmorphic features. This patient represents the smallest isolated chromosomal aberration on distal 15q reported to date. The DNA regulatory proteins, myocyte-specific enhancer factor 2 proteins (MEF2), play a critical role in the control of muscle differentiation and development. One member of this gene family, MEF2A, maps to 15q26. We propose that this region is a candidate locus for diaphragmatic hernia and future investigations should examine the role of MEF2A in diaphragm formation.

Molecular cytogenetic analysis of a de novo balanced X;autosome translocation: Evidence for predominant inactivation of the derivative X chromosome in a girl with multiple malformations

We report on the characterization of a de novo, apparently balanced translocation t(X;15)(p11.3;q26) detected in a girl with multiple congenital malformations. Replication banding studies on Epstein-Barr virus transformed peripheral blood lymphocytes revealed non-random X chromosome inactivation with predominant inactivation of the derivative X chromosome. Using chromosomal fluorescence in situ hybridization (FISH), we located the breakpoints to a 30 kb region on the short arm of the X chromosome band p11.3 and to a 160 kb region defined by BAC RP11-89K11 on the long arm of chromosome 15. Our data suggest that the disruption/disturbance of plant homeo domain (PHD) zinc finger gene KIAA0215 or of another gene (RGN, RNU12, P17.3, or RBM10) in the breakpoint region on the X chromosome is not well tolerated and leads to the selection of cells with an active non-rearranged X chromosome.

Inverted duplication of 15q with terminal deletion in a multiple malformed newborn with intrauterine growth failure and lethal phenotype

We describe the cytogenetic and molecular characterization of an inverted duplication of chromosome 15q with evidence of a terminal deletion of the same rearranged chromosome. The proband was a multiple congenital malformed female with a prenatal diagnosis of trisomy 15q and an extremely severe clinical course. The phenotype of the patient was characterized by marked intrauterine growth retardation, congenital heart defect, "horseshoe" kidney, hand contractures, and clubfeet. The exitus came at 20 days because of progressive cardio-respiratory impairment. Overall, the clinical phenotype appeared more severe than usual trisomy 15q syndrome. Postnatal cytogenetic and molecular studies unraveled a "de novo" inverted duplication of 15q (q21.3-->q26.3), associated with the deletion of the 15q telomere and part of the band 15q26.3. A single copy region spanning approximately 600 kb between the duplicated segments was present. Correlation between the clinical findings of the patient and the phenotype of trisomy 15q reported in literature is also provided.

Prenatal diagnosis of congenital diaphragmatic hernia in a McFadden Kalousek type 2 triploid fetus

Triploidy is characterized by an extra haploid set. We report a rare case of a prenatally diagnosed digynic type (McFadden/Kalousek type 2) triploid fetus with congenital diaphragmatic hernia (CDH). Prenatal ultrasonographic examination allows reliable detection of CDH and it is therefore of great importance for proper parental counselling, as well as performing fetal karyotype for associated chromosomal anomalies.

Retinal dehydrogenase-2 is inhibited by compounds that induce congenital diaphragmatic hernias in rodents

Currently, the etiology of the serious developmental anomaly congenital diaphragmatic hernia (CDH) is unknown. We have used an animal model of CDH to address this issue. We characterized four separate teratogens that produced diaphragmatic defects in embryonic rats that are similar to those in infants with CDH. We then tested the hypothesis that all these agents share the common mechanism of perturbing the retinoid-signaling pathway. Specifically, inhibition of retinal dehydrogenase-2 (RALDH2), a key enzyme necessary for the production of retinoic acid and that is expressed in the developing diaphragm, was assayed by measuring retinoic acid production in cytosolic extracts from an oligodendrocyte cell line. The following compounds all induce posterolateral defects in the rat diaphragm; nitrofen, 4-biphenyl carboxylic acid, bisdiamine, and SB-210661. Importantly, we demonstrate that they all share the common mechanism of inhibiting RALDH2. These data provide an important component of mounting evidence suggesting that the retinoid system warrants consideration in future studies of the etiology of CDH.