Deletion of a 5-cM region at chromosome 8p23 is associated with a spectrum of congenital heart defects

Association between NOS3 gene polymorphisms and genetic susceptibility to congenital heart Disease: A systematic review and meta-analysis

BACKGROUND

Endothelial nitric oxide (NO) produced by endothelial Nitric Oxide Synthase (eNOS) can promote the expression of pro-angiogenic cytokines and is favorable for angiogenesis. However, the relationship between NOS3 gene polymorphisms and genetic susceptibility to congenital heart disease (CHD) was still unclear.

METHODS

We searched five databases including Pubmed, Cochrane Library, Embase, Web of Science, CNKI, and Wan Fang, to find all studies on NOS3 gene polymorphisms and CHD. Rstudio was used to merge the data included in the study to obtain OR, 95%CI, and forest plots.

RESULTS

Five relevant literatures were included, including three sites of NOS3 gene, rs1799983 (G894T), rs2070744 (T-786C), and rs7830 (G10T). Several models including the homozygous model of rs1799983 (G894T) gene polymorphism (TT VS GG: OR = 1.602, 95%CI: 1.098 ∼ 2.337, P = 0.027), rs7830 (G10T) gene polymorphism allele model (A VS C: OR = 1.171, 95%CI: 1.029 ∼ 1.333, P = 0.017), homozygous model (AA VS CC: OR = 1.474, 95%CI: 1.122 ∼ 1.936, P = 0.005) and implicit model (AA VS CC + AC: OR = 1.451, 95%CI: 1.133 ∼ 1.859, P = 0.003) indicated that there was a correlation. The results of the combined analysis of each gene model of rs2070744 (T-786C) gene polymorphism sites were not statistically significant, and their P values were all>0.05.

CONCLUSION

rs1799983 (G894T) and rs7830 (G10T) polymorphic sites might play a role in the susceptibility of sporadic congenital heart disease and increase the risk of CHD. Yet, it is still necessary to expand the sample size and conduct more prospective/retrospective studies to confirm whether the rs2070744 (T-786C) polymorphism tended to increase the incidence of CHD.

8p23.1 deletion: Look out for left ventricular hypertrabeculation and not only congenital heart diseases. Single-center experience and literature revision

Deletions involving the distal portion of the short arm of chromosome 8(8p23.1) show a high phenotypic variability. Congenital heart diseases (CHD) are often described. GATA4 when mutated or deleted is reported to be involved in cardiac morphogenesis. Only twice, left ventricular non compaction (LVNC) was reported in literature in association with 8p23.1 deletion. The present cohort includes five new patients with 8p23.1 deletions including GATA4. The spectrum of CHD is variable. Moreover, in four patients, LV hypertrabeculation was detected and in the fifth LVNC was recognized. Literature revision identified 45 patients with 8p23.1 deletions (encompassing GATA4) and heart involvement. It included wide spectrum of CHD including: heterotaxy spectrum 7/45 (15, 6%), atrioventricular canal 14/45 (balanced 3/45 including two of them with hypoplastic aortic arch; unbalanced 4/45, Fallot-AVC 1/45, partial AVC 3/45, unspecified 3/45), predominant major left heart lesions included 2/45 (4, 4%): interrupted aortic arch and hypoplastic left heart syndrome. Left ventricular hypertrabeculation might be potentially underestimated in patients with 8p23.1 deletion. These might suggest the importance of including microarray analysis in this group of patients. Moreover, 8p23.1 microdeletion or GATA4 variants can be considered in heterotaxy genetic panels.

Sox7 Regulates Lineage Decisions in Cardiovascular Progenitor Cells

Specification of the mesodermal lineages requires a complex set of morphogenetic events orchestrated by interconnected signaling pathways and gene regulatory networks. The transcription factor Sox7 has critical functions in differentiation of multiple mesodermal lineages, including cardiac, endothelial, and hematopoietic. Using a doxycycline-inducible mouse embryonic stem cell line, we have previously shown that expression of Sox7 in cardiovascular progenitor cells promotes expansion of endothelial progenitor cells (EPCs). In this study, we show that the ability of Sox7 to promote endothelial cell fate occurs at the expense of the cardiac lineage. Using ChIP-Seq coupled with ATAC-Seq we identify downstream target genes of Sox7 in cardiovascular progenitor cells and by integrating these data with transcriptomic analyses, we define Sox7-dependent gene programs specific to cardiac and EPCs. Furthermore, we demonstrate a protein-protein interaction between SOX7 and GATA4 and provide evidence that SOX7 interferes with the transcriptional activity of GATA4 on cardiac genes. In addition, we show that Sox7 modulates WNT and BMP signaling during cardiovascular differentiation. Our data represent the first genome-wide analysis of Sox7 function and reveal a critical role for Sox7 in regulating signaling pathways that affect cardiovascular progenitor cell differentiation.

Is interstitial 8p23 microdeletion responsible of 46,XY gonadal dysgenesis? One case report from birth to puberty

BACKGROUND

Chromosome 8p deletions are associated with a variety of conditions, including cardiac abnormalities, mental, behavioral problems with variable morphotype and genitourinary anomalies in boys.

METHODS

We describe the follow-up over almost 15 years of a boy who initially presented with perineal hypospadias with a micropenis and cryptorchidism with 46,XY DSD.

RESULTS

Imaging, pathology, and hormonal exploration suggested gonadal dysgenesis. Further genetic studies were deemed necessary during follow-up. The child's further development recommended further genetic analyses. High-resolution analysis showed an interstitial deletion on the short arm of a chromosome 8: 46,XY,del(8)(p23.1p23.1). We reviewed the literature and found 102 cases including 54 boys: 62.7% had mental problems, 50.9% a dysmorphic disorder, 55.9% cardiac anomalies, and 46.3% of the boys had genitourinary anomalies. Our patient's genital abnormalities can be explained by the haploinsufficiency of the genes, such as GATA4 (OMIM 600576) that are included in the deleted area.

CONCLUSION

This case of severe 46,XY DSD raises the question of the role played by 8p23 microdeletion in gonadal dysgenesis. Clinicians are encouraged to look for this anomaly on chromosome 8 in cases of unexplained gonadal dysgenesis even when few signs suggestive of this anomaly are present.

Heterozygous missense mutations in NFATC1 are associated with atrioventricular septal defect

Atrioventricular septal defect (AVSD) may occur as part of a complex disorder (e.g., Down syndrome, heterotaxy), or as isolate cardiac defect. Multiple lines of evidence support a role of calcineurin/NFAT signaling in AVSD, and mutations in CRELD1, a protein functioning as a regulator of calcineurin/NFAT signaling have been reported in a small fraction of affected subjects. In this study, 22 patients with isolated AVSD and 38 with AVSD and heterotaxy were screened for NFATC1 gene mutations. Sequence analysis identified three missense variants in three individuals, including a subject with isolated AVSD [p.(Ala367Val)], an individual with AVSD and heterotaxy [p.(Val210Met)], and a subject with AVSD, heterotaxy, and oculo-auriculo-vertebral spectrum (OAVS) [p.(Ala696Thr)], respectively. The latter was also heterozygous for a missense change in TBX1 [p.(Pro86Leu)]. Targeted resequencing of genes associated with AVSD, heterotaxy, or OAVS excluded additional hits in the three mutation-positive subjects. Functional characterization of NFATC1 mutants documented defective nuclear translocation and decreased transcriptional transactivation activity. When expressed in zebrafish, the three NFATC1 mutants caused cardiac looping defects and altered atrioventricular canal patterning, providing evidence of their functional relevance in vivo. Our findings support a role of defective NFATC1 function in the etiology of isolated and heterotaxy-related AVSD.

Isolated chromosome 8p23.2‑pter deletion: Novel evidence for developmental delay, intellectual disability, microcephaly and neurobehavioral disorders

The current study presents a patient carrying a de novo ~6 Mb deletion of the isolated chromosome 8p23.2-pter that was identified with a single-nucleotide polymorphism array. The patient was characterized by developmental delay (DD)/intellectual disability (ID), microcephaly, autism spectrum disorder, attention-deficit/hyperactivity disorders and mildly dysmorphic features. The location, size and gene content of the deletion observed in this patient were compared with those in 7 patients with isolated 8p23.2 to 8pter deletions reported in previous studies (4 patients) or recorded in the Database of Chromosomal Imbalance and Phenotype in Humans Using Ensembl Resources (DECIPHER) database (3 patients). The deletions reported in previous studies were assessed using a chromosomal microarray analysis. The 8p23.2-pter deletion was a distinct microdeletion syndrome, as similar phenotypes were observed in patients with this deletion. Furthermore, following a detailed review of the potential associations between the genes located from 8p23.2 to 8pter and their clinical significance, it was hypothesized that DLG associated protein 2, ceroid-lipofuscinosis neuronal 8, Rho guanine nucleotide exchange factor 10 and CUB and sushi multiple domains 1 may be candidate genes for DD/ID, microcephaly and neurobehavioral disorders. However, firm evidence should be accumulated from high-resolution studies of patients with small, isolated, overlapping and interstitial deletions involving the region from 8p23.2 to 8pter. These studies will allow determination of genotype-phenotype associations for the specific genes crucial to 8p23.2-pter.

De novo unbalanced translocation (4p duplication/8p deletion) in a patient with autism, OCD, and overgrowth syndrome

Chromosomal abnormalities, such as unbalanced translocations and copy number variants (CNVs), are found in autism spectrum disorders (ASDs) [Sanders et al. (2011) Neuron 70: 863-885]. Many chromosomal abnormalities, including sub microscopic genomic deletions and duplications, are missed by G-banded karyotyping or Fragile X screening alone and are picked up by chromosomal microarrays [Shen et al. (2010) Pediatrics 125: e727-735]. Translocations involving chromosomes 4 and 8 are possibly the second most frequent translocation in humans and are often undetected in routine cytogenetics [Giglio et al. (2002) Circulation 102: 432-437]. Deletions of 4p16 have been associated with Wolf-Hirschhorn syndrome while 4p16 duplications have been associated with an overgrowth syndrome and mild to moderate mental retardation [Partington et al. (1997) Journal of Medical Genetics 34: 719-728]. The 8p23.3 region contains the autism candidate gene DLGAP2, which can contribute to autism when disrupted [Marshall et al. (2008) The American Journal of Human Genetics 82: 477-488] . There has been a case report of a family with autism spectrum disorder (ASD), prominent obsessional behavior, and overgrowth in patients with der (8) t (4;8) p (16;23) [Partington et al. (1997)]. This is an independent report of a male patient with autism, obsessive compulsive disorder (OCD), attention-deficit hyperactivity disorder (ADHD), and an overgrowth syndrome, whose de novo unbalanced translocation der (8) t (4;8) p (16.1→ter; 23.1→ter) was initially missed by routine cytogenetics but detected with SNP microarray, allowing higher resolution of translocation breakpoints.

A novel mutation in exon 1 of GATA4 in Egyptian patients with congenital heart disease

BACKGROUND/AIM

Congenital heart disease (CHD) is a common birth defect. Many studies have reported GATA4 mutations in patients with CHD, mainly septal defects. This study aimed to investigate the GATA4 exon 1 mutation in Egyptian patients with isolated congenital heart defects as a possible causative mutation.

MATERIALS AND METHODS

Screening for mutations or any sequence variations in exon 1 of the GATA4 gene was carried out by PCR amplification followed by direct sequencings in 165 Egyptian patients with different nonsyndromic congenital heart diseases and 93 controls who were matched in terms of age and sex. Thorough clinical assessments were done for all subjects, along with X-ray, 2D echocardiography, and Doppler examinations.

RESULTS

The most common CHD among our cases was isolated ventricular septal defect (VSD) in 47.3% (78/165), followed by isolated atrial septal defect. A novel nonsynonymous sequence variation in fragment 2 (P193H) of exon 1 of GATA4 was detected in 15 (9.1%) of the subjects with septal defects. This mutation was not seen in any of the control group subjects.

CONCLUSION

There is a high prevalence of exon 1 GATA4 mutation (9.1%) in our study compared to other studies in different populations, which may correlate with different ethnic populations.

Identification of candidate genes for congenital heart defects on proximal chromosome 8p

With the application of advanced molecular cytogenetic techniques, the number of patients identified as having abnormal chromosome 8p has increased progressively. Individuals with terminal 8p deletion have been extensively described in previous studies. The manifestations usually include cardiac anomalies, developmental delay/mental retardation, craniofacial abnormalities, and multiple other minor anomalies. However, some patients with proximal deletion also presented with similar phenotypic features. Here we describe a female child with an 18.5-Mb deletion at 8p11.23–p22 that include the cardiac-associated loci NKX2-6 and NRG1. Further mutation screening of these two candidate genes in 143 atrial septal defect patients, two heterozygous mutations NKX2-6 (c.1A > T) and NRG1 (c.1652G > A) were identified. The mutations were described for the first time in patients with congenital heart disease (CHD). The c.1A > T NKX2-6 generated a protein truncated by 45 amino acids with a decreased level of mRNA expression, whereas the NRG1 mutation had no significant effect on protein functions. Our findings suggest that 8p21-8p12 may be another critical region for 8p-associated CHD, and some cardiac malformations might be due to NKX2-6 haploinsufficiency. This study also links the NKX2-6 mutation to ASD for the first time, providing novel insight into the molecular underpinning of this common form of CHD.

Genetic Variants in Isolated Ebstein Anomaly Implicated in Myocardial Development Pathways

Ebstein anomaly (EA) is a rare heart defect in which the tricuspid valve is malformed and displaced. The tricuspid valve abnormalities can lead to backflow of blood from the right ventricle to the right atrium, preventing proper circulation of blood to the lungs. Although the etiology of EA is largely unresolved, increased prevalence of EA in those with a family history of congenital heart disease suggests EA has a genetic component. Copy number variants (CNVs) are a major source of genetic variation and have been implicated in a range of congenital heart defect phenotypes. We performed a systematic, genome-wide search for CNVs in 47 isolated EA cases using genotyping microarrays. In addition, we used a custom HaloPlex panel to sequence three known EA genes and 47 candidate EA genes. We identified 35 candidate CNVs in 24 (51%) EA cases. Rare sequence variants in genes associated with cardiomyopathy were identified in 11 (23%) EA cases. Two CNVs near the transcriptional repressor HEY1, a member of the NOTCH signaling pathway, were identified in three unrelated cases. All other candidate CNVs were each identified in a single case. At least 11 of 35 candidate CNVs include genes involved in myocardial development or function, including multiple genes in the BMP signaling pathway. We identified enrichment of gene sets involved in histone modification and cardiomyocyte differentiation, supporting the involvement of the developing myocardium in the etiology of EA. Gene set enrichment analysis also identified ribosomal RNA processing, a potentially novel pathway of altered cardiac development in EA. Our results suggest an altered myocardial program may contribute to abnormal tricuspid valve development in EA. Future studies should investigate abnormal differentiation of cardiomyocytes as a potential etiological factor in EA.

8p23.1 Interstitial Deletion in a Patient with Congenital Cardiopathy, Neurobehavioral Disorders, and Minor Signs Suggesting 22q11.2 Deletion Syndrome

Copy number variation studies of known disorders have the potential to improve the characterization of clinical phenotypes and may help identifying candidate genes and their pathways. The authors described a child with congenital heart disease, microcephaly, facial dysmorphisms, developmental delay, learning difficulties, and behavioral problems. There was initially a clinical suspicion of 22q11.2 deletion syndrome (22q11.2 DS), but molecular cytogenetic analysis (array genomic hybridization [aGH]) showed the presence of a de novo 3.6-Mb interstitial microdeletion in 8p23.1. The main features of 8p23.1 DS include congenital heart disease and behavioral problems, in addition to minor dysmorphisms and mental delay. Therefore, this article highlights the application of aGH to investigate 8p23.1 deletion in nonconfirmed 22q11.2 DS patients presenting neurobehavioral disorders, congenital cardiopathy, and minor dysmorphisms.

Genetic basis of congenital cardiovascular malformations

Cardiovascular malformations are a singularly important class of birth defects and due to dramatic improvements in medical and surgical care, there are now large numbers of adult survivors. The etiologies are complex, but there is strong evidence that genetic factors play a crucial role. Over the last 15 years there has been enormous progress in the discovery of causative genes for syndromic heart malformations and in rare families with Mendelian forms. The rapid characterization of genomic disorders as major contributors to congenital heart defects is also notable. The genes identified encode many transcription factors, chromatin regulators, growth factors and signal transduction proteins- all unified by their required roles in normal cardiac development. Genome-wide sequencing of the coding regions promises to elucidate genetic causation in several disorders affecting cardiac development. Such comprehensive studies evaluating both common and rare variants would be essential in characterizing gene-gene interactions, as well as in understanding the gene-environment interactions that increase susceptibility to congenital heart defects.

Regulation of fetal gene expression in heart failure

During the processes leading to adverse cardiac remodeling and heart failure, cardiomyocytes react to neurohumoral stimuli and biomechanical stress by activating pathways that induce pathological hypertrophy. The gene expression patterns and molecular changes observed during cardiac hypertrophic remodeling bare resemblance to those observed during fetal cardiac development. The re-activation of fetal genes in the adult failing heart is a complex biological process that involves transcriptional, posttranscriptional and epigenetic regulation of the cardiac genome. In this review, the mechanistic actions of transcription factors, microRNAs and chromatin remodeling processes in regulating fetal gene expression in heart failure are discussed.

A potential relationship among beta-defensins haplotype, SOX7 duplication and cardiac defects

OBJECTIVE

To determine the pathogenesis of a patient born with congenital heart defects, who had appeared normal in prenatal screening.

METHODS

In routine prenatal screening, G-banding was performed to analyse the karyotypes of the family and fluorescence in situ hybridization was used to investigate the 22q11.2 deletion in the fetus. After birth, the child was found to be suffering from heart defects by transthoracic echocardiography. In the following study, sequencing was used to search for potential mutations in pivotal genes. SNP-array was employed for fine mapping of the aberrant region and quantitative real-time PCR was used to confirm the results. Furthermore, other patients with a similar phenotype were screened for the same genetic variations. To compare with a control, these variations were also assessed in the general population.

RESULTS

The child and his mother each had a region that was deleted in the beta-defensin repeats, which are usually duplicated in the general population. Besides, the child carried a SOX7-gene duplication. While this duplication was not detected in his mother, it was found in two other patients with cardiac defects who also had the similar deletion in the beta-defensin repeats.

CONCLUSION

The congenital heart defects of the child were probably caused by a SOX7-gene duplication, which may be a consequence of the partial haplotype of beta-defensin regions at 8p23.1. To our knowledge, this is the first congenital heart defect case found to have the haplotype of beta-defensin and the duplication of SOX7.

Pre- and postnatal findings in a patient with a novel rec(8)dup(8q)inv(8)(p23.2q22.3) associated with San Luis Valley syndrome

San Luis Valley syndrome, which is due to a recombinant chromosome 8 (SLV Rec8) found in Hispanic individuals from Southwestern United States, is a well-established syndrome associated with intellectual disabilities and, frequently, severe cardiac anomalies. We report for the first time on a Moroccan girl with a recombinant chromosome 8 prenatally diagnosed as SLV Rec8 by conventional cytogenetic studies. At birth, an oligo array-CGH (105 K) defined the breakpoints and the size of the imbalanced segments, with a deletion of ≈ 2.27 Mb (8p23.2-pter) and a duplication of ≈ 41.93 Mb (8q22.3-qter); thus this recombinant chromosome 8 differed from that previously reported in SLV Rec8 syndrome. The phenotypic characteristics associated with this SLV Rec8 genotype overlap those commonly found in patients with 8q duplication reported in the literature. We review SLV Rec8 and other chromosome 8 aberrations and suggest that the overexpression of cardiogenic genes located at 8q may be the cause of the cardiac defects in this patient.

Chromosomal imbalance letter: Phenotypic consequences of combined deletion 8pter and duplication 15qter

Exact breakpoint determination by oligonucleotide array-CGH has improved the analysis of genotype-phenotype correlations in cases with chromosome aberrations allowing a more accurate definition of relevant genes, particularly their isolated or combined impact on the phenotype in an unbalanced state. Chromosomal imbalances have been identified as one of the major causes of mental retardation and/or malformation syndromes and they are observed in ~2-5% of the cases. Here we report a female child born to non-consanguineous parents and having multiple congenital anomalies such as atrial septal defect and multiple ventricular septal defects, convergent strabismus, micropthalmia, seizures and mental retardation, with her head circumference and stature normal for her age. Cytogenetic study suggested 46,XX,add(8)(p23). Further analysis by array-CGH using 44K oligonucleotide probe confirmed deletion on 8p23.3p23.1 of 7.1 Mb and duplication involving 15q23q26.3 of 30 Mb size leading to 46,XX,der(8)t(8;15)(p23.3;q23)pat.arr 8p23.3p23.1(191,530-7,303,237)x1,15q23q26.3(72,338,961-102,35,195)x3. The unique phenotypic presentation in our case may have resulted from either loss or gain of a series of contiguous genes which may have resulted in a direct phenotypic effect and/or caused a genetic regulatory disturbance. Double segmental aberrations may have conferred phenotypic variability, as in our case, making it difficult to predict the characteristics that evolved as a result of the global gene imbalance, caused by the concomitant deletion and duplication.

[Subvalvular aortic stenosis associated with 8p23 deletion]

We report the case of a 35-year-old man admitted due to heart failure, who had had moderate cognitive deficit, craniofacial dysmorphism, epilepsy, panic attacks and congenital heart disease (subvalvular aortic stenosis) associated with chronic atrial fibrillation since childhood. In view of his facial dysmorphism and clinical presentation, karyotype analysis was performed and revealed a de novo interstitial deletion in chromosome 8 in the region p23.1-p23.2. This is a rare chromosomal anomaly (about 50 descriptions in the literature), whose most common manifestations include heart defects, cognitive retardation and behavioral disturbances. In this paper we present the first case with associated subvalvular aortic stenosis and review the literature on this chromosomal abnormality.

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.

Molecular cytogenetic characterization and genotype/phenotype analysis in a patient with a de novo 8p23.2p23.3 deletion/12p13.31p13.33 duplication

Genomic copy number imbalances are being increasingly identified as an important cause of intellectual disability (ID) and behavioral disturbances. This article reports the clinical features, and long term follow-up of a patient with neurodevelopmental, cognitive, and behavioral abnormalities associated with facial dysmorphism, CNS anomalies, and epilepsy. The karyotype was normal; array CGH testing revealed a de novo cryptic aberration with a terminal 8p23.2p23.3 deletion, and a concomitant 12p13.31p13.33 duplication, of 6.86 Mb, and 8.49 Mb, respectively. Our patient clinical features are compared to those of partial 8 monosomy and/or partial 12p trisomy cases reported in literature, in order to establish genotype-phenotype correlations. For some features, for example, electroencephalogram (EEG) abnormalities and epilepsy, both abnormalities seem to make a contribution, while most phenotypic traits have been assigned to 8p monosomy or to 12p trisomy, contributing to a tentative phenotype map for partial monosomy of the short arm of chromosome 8, and trisomy of the short arm of chromosome 12.

Dextrocardia, atrial septal defect, severe developmental delay, facial anomalies, and supernumerary ribs in a child with a complex unbalanced 8;22 translocation including partial 8p duplication

We report on a child with dextrocardia, atrial septal defect (ASD), severe developmental delay, hypotonia, 13 pairs of ribs, left preauricular choristoma, hirsutism, and craniofacial abnormalities. Prenatal cytogenetic evaluation showed karyotype 46,XY,?dup(8p)ish del(8)pter. Postnatal array CGH demonstrated a 6.8 Mb terminal deletion at 8p23.3-p23, an interstitial 31.1 Mb duplication within 8p23.1-p11, and a terminal duplication of 0.24 Mb at 22q13.33, refining the karyotype to 46,XY,der(8)dup(8)(p23.1p11.1)t(8;22)(p23.1;q13.1).ish der(8)dup(8)(p23.1p11.1)t(8;22)(p23.1;q13.1) (D8S504-,MS607 + ,ARSA + ,D8Z1 + , RP115713 + +). Previous reports of distal 8p deletion, 8p duplication, and distal 22q duplication have shown similar manifestations, including congenital heart disease, intellectual impairment, and multiple minor anomalies. We correlate the patient's clinical findings with these particular areas of copy number. This case study supports the use of aCGH to identify subtle chromosomal rearrangement in infants with cardiac malformation as their most significant or only apparent birth defect. Additionally, it illustrates why aCGH is essential in the description of chromosome rearrangements, even those seemingly visible via routine karyotype. This method shows that there is often greater complexity submicroscopically, essential to an adequate understanding of a patient's genotype and phenotype.

Transcription factor pathways and congenital heart disease

Congenital heart disease is a major cause of morbidity and mortality throughout life. Mutations in numerous transcription factors have been identified in patients and families with some of the most common forms of cardiac malformations and arrhythmias. This review discusses transcription factor pathways known to be important for normal heart development and how abnormalities in these pathways have been linked to morphological and functional forms of congenital heart defects. A comprehensive, current list of known transcription factor mutations associated with congenital heart disease is provided, but the review focuses primarily on three key transcription factors, Nkx2-5, GATA4, and Tbx5, and their known biochemical and genetic partners. By understanding the interaction partners, transcriptional targets, and upstream activators of these core cardiac transcription factors, additional information about normal heart formation and further insight into genes and pathways affected in congenital heart disease should result.

The general anesthesia experience of deletion 8p syndrome patient -A case report-

A deletion 8p syndrome is a relatively uncommon congenital disease characterized by mental retardation associated with multiple malformation that make anesthetic management a challenge. Anesthetic management of a patient with deletion 8p syndrome may pose a serious problem mainly from difficult tracheal intubation, aspiration complication and cardiac malformation. We experienced a case of 10 year-old boy with a deletion 8p syndrome who underwent appendectomy under the general anesthesia. Intubation was performed by video glidescope after unsuccessful attempt with Macintosh laryngoscope. A high arched palate, short neck, poor patient cooperation due to mental retardation and occasional autistic behaviour made airway management difficult. This case should alert anesthesiologists to the greater difficulties of managing patients with deletion 8p syndrome.

GATA4 mutations in 357 unrelated patients with congenital heart malformation

Congenital heart disease (CHD) represents one of the most common birth defects, but the genetic causes remain largely unknown. Mutations in GATA4, encoding a zinc finger transcription factor with a pivotal role in heart development, have been associated with CHD in several familial cases and a small subset of sporadic patients. To estimate the pathogenetic role of GATA4 in CHD, we screened for mutations in 357 unrelated patients with different congenital heart malformations. In addition to nine synonymous changes, we identified two known (A411V and D425N) and two novel putative mutations (G69D and P163R) in five patients with atrial or ventricular septal defects that were not seen in control subjects. The four mutations did not show altered GATA4 transcriptional activity in synergy with the transcription factors NKX2-5 and TBX20. Our data expand the spectrum of mutations associated with cardiac septal defects but do not support GATA4 mutations as a common cause of CHD.

Periconceptional nutrient intakes and risks of conotruncal heart defects

BACKGROUND

Few inquiries into periconceptional nutrition, other than folate, and risk of heart defects exist. We investigated the observed association between conotruncal heart defects and periconceptional vitamin use, as well as potential associations with other dietary nutrients.

METHODS

Data derived from a population-based, case-control study of fetuses and liveborn infants among California births between July 1999 and June 2004; 76% of eligible case mothers and 77% of eligible control mothers were interviewed. Cases included 140 with d-transposition of great arteries (dTGA), and 163 with tetralogy of Fallot (TOF). Total number of controls was 698. Use of vitamins was elicited by questionnaire for the periconceptional period. Dietary nutrient intake was elicited by a well-known food frequency questionnaire.

RESULTS

The odds ratio for dTGA associated with supplemental vitamin use was 1.0 (95% confidence interval [CI], 0.7-1.5) and for TOF was 0.9 (95% CI, 0.6-1.3). We observed increased risks associated with lower dietary intakes of linoleic acid, total carbohydrate, and fructose for dTGA, whereas decreased risks were observed for lower intakes of total protein and methionine for TOF. Lower dietary intake of several micronutrients-namely folate, niacin, riboflavin, and vitamins B(12), A, and E, even after simultaneous adjustment for other studied nutrients-was associated with increased risk of dTGA but not TOF. These associations were observed among women who did not use vitamin supplements periconceptionally. Analytic consideration of several potential confounders did not reveal alternative interpretations of the results.

CONCLUSION

Evidence continues to accumulate to show that nutrients, particularly folate, influence risks of structural birth defects. Our results extend observations that other nutrients may also be important in heart development.

8p23.1 duplication syndrome differentiated from copy number variation of the defensin cluster at prenatal diagnosis in four new families

BACKGROUND

The 8p23.1 duplication syndrome and copy number variation of the 8p23.1 defensin gene cluster are cytogenetically indistinguishable but distinct at the molecular level. To our knowledge, the 8p23.1 duplication syndrome has been described at prenatal diagnosis only once and we report our experience with four further apparent duplications ascertained at prenatal diagnosis.

METHODS

Additional material at band 8p23.1 was detected using conventional G-banded cytogenetics in each case. Multiplex Ligation-dependent Probe Amplification (MLPA) or Fluorescence In Situ Hybridisation (FISH) were used depending on whether only DNA (Cases 1 and 4) or cytogenetic preparations (Cases 2 and 3) were available from the laboratory of origin. The extent of the duplication in Case 1 was retrospectively determined using array Comparative Genomic Hybridisation (array CGH).

RESULTS

Three cases of 8p23.1 duplication syndrome were found (Cases 1 to 3). Two were de novo and continued to term and the third, a paternally transmitted duplication, was terminated because of a previous child with psychomotor delay and 8p23.1 duplication syndrome. Case 1 was ascertained with a hypoplastic left heart but the ventricular septal and interventricular defects, in Cases 2 and 3 respectively, were found after ascertainment for advanced maternal age. By contrast, case 4 was a maternally transmitted copy number variation of the defensin cluster with normal outcome.

CONCLUSIONS

Our data underline the need to differentiate 8p23.1 duplications from copy number variation of the defensin cluster using FISH, MLPA or array CGH. Cardiac defects were ascertained by ultrasound in only one of the three duplication 8p23.1 pregnancies but were visible in two of the three at 21 to 22 weeks gestation. Our results provide further evidence that both deletion and duplication of the GATA4 transcription factor can give rise to a variety of conotruncal heart defects with variable penetrance and expressivity.

Chromosome 8p23.1 deletions as a cause of complex congenital heart defects and diaphragmatic hernia

Recurrent interstitial deletion of a region of 8p23.1 flanked by the low copy repeats 8p-OR-REPD and 8p-OR-REPP is associated with a spectrum of anomalies that can include congenital heart malformations and congenital diaphragmatic hernia (CDH). Haploinsufficiency of GATA4 is thought to play a critical role in the development of these birth defects. We describe two individuals and a monozygotic twin pair discordant for anterior CDH all of whom have complex congenital heart defects caused by this recurrent interstitial deletion as demonstrated by array comparative genomic hybridization. To better define the genotype/phenotype relationships associated with alterations of genes on 8p23.1, we review the spectrum of congenital heart and diaphragmatic defects that have been reported in individuals with isolated GATA4 mutations and interstitial, terminal, and complex chromosomal rearrangements involving the 8p23.1 region. Our findings allow us to clearly define the CDH minimal deleted region on chromosome 8p23.1 and suggest that haploinsufficiency of other genes, in addition to GATA4, may play a role in the severe cardiac and diaphragmatic defects associated with 8p23.1 deletions. These findings also underscore the importance of conducting a careful cytogenetic/molecular analysis of the 8p23.1 region in all prenatal and postnatal cases involving congenital defects of the heart and/or diaphragm.

Increased prevalence of cardiovascular defects among 56,709 California twin pairs

This study compared the prevalence of cardiovascular defects in twin and singleton births and explored the influences of zygosity (monozygotic and dizygotic) and maternal age (<35 and >or=35 years of age) on concordance. Data on twin and singleton infants with (n = 628 twin pairs and n = 14,078 singletons) and without (n = 53,974 twin pairs and n = 4,858,255 singletons) cardiovascular defects were obtained from the California Birth Defects Monitoring Program and the California vital statistics birth and fetal death records during the period 1983-2003. Prevalence ratios (PR) (prevalence of twin/singleton) and approximate 95% confidence intervals were calculated for 16 congenital cardiovascular categories. Poisson regression techniques using log-linear models were employed to assess whether the probability of concordance of defects within each cardiovascular category varied by zygosity or maternal age. An increased prevalence was observed in twins compared to singletons in all 16 cardiovascular categories. Seven of the cardiovascular categories had at least double the prevalence in twins compared to singletons. Like-sex twins, as a proxy of monozygosity, had an increased prevalence of cardiovascular defects compared to unlike sex twins. Probabilities of concordance for flow lesions were higher among monozygotic than dizygotic twins. Our study provides evidence that twinning is associated with more cardiovascular defects than singletons. Increased concordance for flow lesions in monozygotic twins was observed, an observation that is in agreement with findings from familial recurrence studies of cardiovascular defects.

Clinical and molecular characterization of two patients with a 6.75 Mb overlapping deletion in 8p12p21 with two candidate loci for congenital heart defects

Clinical and molecular characteristics of two patients with a 6.75Mb overlapping interstitial deletion in the 8p12p21 region are described and compared with previously reported cases with an overlapping deletion. The most common characteristics of interstitial deletions of proximal 8p are developmental delay, postnatal microcephaly and growth retardation. Other frequently reported findings are hypogonadism associated with haploinsufficiency of GNRH1 and ocular problems. Congenital heart anomalies are also common and might at least to some extent be due to haploinsufficiency of NKX2-6 or NRG1. The aforementioned clinical characteristics should be considered in the care of patients with a proximal interstitial 8p12p21 deletion.

GATA4 sequence variants in patients with congenital heart disease

BACKGROUND

Recent reports have identified mutations in the transcription factor GATA4 in familial cases of cardiac septal defects. The prevalence of GATA4 mutations in the population of patients with septal defects is unknown. Given that patients with septal and conotruncal defect can share a common genetic basis, it is unclear whether patients with additional types of CHD might also have GATA4 mutations.

AIMS

To explore these questions by investigating a large population of 628 patients with either septal or conotruncal defects for GATA4 sequence variants.

METHODS

The GATA4 coding region and exon-intron boundaries were investigated for sequence variants using denaturing high-performance liquid chromatography or conformation-sensitive gel electrophoresis. Samples showing peak or band shifts were reamplified from genomic DNA and sequenced.

RESULTS

Four missense sequence variants (Gly93Ala, Gln316Glu, Ala411Val, Asp425Asn) were identified in five patients (two with atrial septal defect, two with ventricular septal defect and one with tetralogy of Fallot), which were not seen in a control population. All four affected amino acid residues are conserved across species, and two of the sequence variants lead to changes in polarity. Ten synonymous sequence variants were also identified in 18 patients, which were not seen in the control population.

CONCLUSIONS

These data suggest that non-synonymous GATA4 sequence variants are found in a small percentage of patients with septal defects and are very uncommonly found in patients with conotruncal defects.

From microscopes to microarrays: dissecting recurrent chromosomal rearrangements

Submicroscopic chromosomal rearrangements that lead to copy-number changes have been shown to underlie distinctive and recognizable clinical phenotypes. The sensitivity to detect copy-number variation has escalated with the advent of array comparative genomic hybridization (CGH), including BAC and oligonucleotide-based platforms. Coupled with improved assemblies and annotation of genome sequence data, these technologies are facilitating the identification of new syndromes that are associated with submicroscopic genomic changes. Their characterization reveals the role of genome architecture in the aetiology of many clinical disorders. We review a group of genomic disorders that are mediated by segmental duplications, emphasizing the impact that high-throughput detection methods and the availability of the human genome sequence have had on their dissection and diagnosis.

Characterization and evolution of the novel gene family FAM90A in primates originated by multiple duplication and rearrangement events

Genomic plasticity of human chromosome 8p23.1 region is highly influenced by two groups of complex segmental duplications (SDs), termed REPD and REPP, that mediate different kinds of rearrangements. Part of the difficulty to explain the wide range of phenotypes associated with 8p23.1 rearrangements is that REPP and REPD are not yet well characterized, probably due to their polymorphic status. Here, we describe a novel primate-specific gene family, named FAM90A (family with sequence similarity 90), found within these SDs. According to the current human reference sequence assembly, the FAM90A family includes 24 members along 8p23.1 region plus a single member on chromosome 12p13.31, showing copy number variation (CNV) between individuals. These genes can be classified into subfamilies I and II, which differ in their upstream and 5'-untranslated region sequences, but both share the same open reading frame and are ubiquitously expressed. Sequence analysis and comparative fluorescence in situ hybridization studies showed that FAM90A subfamily II suffered a big expansion in the hominoid lineage, whereas subfamily I members were likely generated sometime around the divergence of orangutan and African great apes by a fusion process. In addition, the analysis of the Ka/Ks ratios provides evidence of functional constraint of some FAM90A genes in all species. The characterization of the FAM90A gene family contributes to a better understanding of the structural polymorphism of the human 8p23.1 region and constitutes a good example of how SDs, CNVs and rearrangements within themselves can promote the formation of new gene sequences with potential functional consequences.

Genetic heterogeneity and phenotypic anomalies in children with atrioventricular canal defect and tetralogy of Fallot

Tetralogy of Fallot associated with the atrioventricular canal defect has been usually reported in association with Down syndrome. The aim of the present study was to describe the cardiac aspects and the genetic anomalies in children with this association of heart defects. We identified 64 patients with atrioventricular canal defect tetralogy of Fallot. All children underwent complete cardiovascular, clinical phenotypic and genetic evaluation. A genetic syndrome or extracardiac anomalies were found in 56 patients (87.5%). Down syndrome (43 patients, 67.2%) was the most frequent genetic diagnosis. Other syndromes were 8p deletion, trisomy 13, duplication 5p, cranio-cerebello-cardiac syndrome, Cantrell syndrome, CHARGE association, VACTERL association, and DiGeorge syndrome related to maternal diabetes. No patients in our series had 22q11 deletion. Tetralogy of Fallot with extreme dextroposition of the aorta was found in seven patients (only one with Down syndrome). Additional cardiac malformations were present in 23 patients (only 11 with Down syndrome). The association between atrioventricular canal defect and tetralogy of Fallot represents a cardiac phenotype with strong genetic characteristics. For this reason, a careful genetic examination is required. Our study confirms the high prevalence of Down syndrome, but also reveals a significant genetic heterogeneity. Additional cardiac defects are prevalent in patients without Down syndrome.

Duplications and copy number variants of 8p23.1 are cytogenetically indistinguishable but distinct at the molecular level

It has been proposed that duplications of 8p23.1 are either euchromatic variants of the 8p23.1 defensin domain with no phenotypic consequences or true duplications associated with developmental delay and heart defects. Here, we provide evidence for both alternatives in two new families. A duplication of most of band 8p23.1 (circa 5 Mb) was found in a girl of 8 years with pulmonary stenosis and mild language delay. BAC fluorescence in situ hybridisation (FISH) and multiplex amplifiable probe hybridisation (MAPH) showed that the two copies of the duplicated segment were sited, in an alternating fashion, between three copies of a circa 300-450 kb segment from 8p23.1 distal to REPD. Copy number of the variable 8p23.1 defensin domain was consistent with duplication but within the normal range. Duplication of the GATA-binding protein 4 gene (GATA4) in this patient and others with and without heart defects, suggests it is a dosage-sensitive gene with variable penetrance. A cytogenetically similar duplication of 8p23.1 was found at prenatal diagnosis in a fetus, father and grandmother. There was no duplication using BAC FISH but MAPH showed 11 copies of the 360 kb variable defensin domain which is within the expanded range found in previous euchromatic variant carriers. Semiquantitative FISH (SQ-FISH) was consistent with a simultaneous expansion of the adjacent olfactory receptor repeats. These results distinguish duplications of 8p23.1 with clinically significant consequences from benign copy number variants, which have not yet been associated with qualitative or quantitative traits.

Trisomy 3q25.1-qter and monosomy 8p23.1-pter in a patient: cytogenetic and molecular analysis with delineation of the phenotype

We describe a 4-year-old boy with partial 3q trisomy and distal 8p monosomy. The patient presented with mental retardation, dysmorphic face, congenital heart defect, brain and genital anomalies, and behavioral problems. The conventional cytogenetic analysis showed a 46,XY,add(8p) karyotype. Reverse painting and microsatellite analysis demonstrated a partial monosomy of 8p23.1 --> pter and a partial trisomy of 3q25.1 --> qter. The data suggest that the chromosomal rearrangement originated from a de novo translocation in a paternal germinal cell. The phenotype observed in our patient resulted from the combination of those defects described in the isolated dup(3q) and distal del(8p) syndromes.