Echocardiographic evaluation of the spectrum of cardiac anomalies associated with trisomy 13 and trisomy 18

From genes to therapy: A comprehensive exploration of congenital heart disease through the lens of genetics and emerging technologies

Congenital heart disease (CHD) affects approximately 1 % of live births worldwide, making it the most common congenital anomaly in newborns. Recent advancements in genetics and genomics have significantly deepened our understanding of the genetics of CHDs. While the majority of CHD etiology remains unclear, evidence consistently indicates that genetics play a significant role in its development. CHD etiology holds promise for enhancing diagnosis and developing novel therapies to improve patient outcomes. In this review, we explore the contributions of both monogenic and polygenic factors of CHDs and highlight the transformative impact of emerging technologies on these fields. We also summarized the state-of-the-art techniques, including targeted next-generation sequencing (NGS), whole genome and whole exome sequencing (WGS, WES), single-cell RNA sequencing (scRNA-seq), human induced pluripotent stem cells (hiPSCs) and others, that have revolutionized our understanding of cardiovascular disease genetics both from diagnosis perspective and from disease mechanism perspective in children and young adults. These molecular diagnostic techniques have identified new genes and chromosomal regions involved in syndromic and non-syndromic CHD, enabling a more defined explanation of the underlying pathogenetic mechanisms. As our knowledge and technologies continue to evolve, they promise to enhance clinical outcomes and reduce the CHD burden worldwide.

The American Association for Thoracic Surgery (AATS) 2023 Expert Consensus Document: Recommendation for the care of children with trisomy 13 or trisomy 18 and a congenital heart defect

OBJECTIVES

Recommendations for surgical repair of a congenital heart defect in children with trisomy 13 or trisomy 18 remain controversial, are subject to biases, and are largely unsupported with limited empirical data. This has created significant distrust and uncertainty among parents and could potentially lead to suboptimal care for patients. A working group, representing several clinical specialties involved with the care of these children, developed recommendations to assist in the decision-making process for congenital heart defect care in this population. The goal of these recommendations is to provide families and their health care teams with a framework for clinical decision making based on the literature and expert opinions.

METHODS

This project was performed under the auspices of the AATS Congenital Heart Surgery Evidence-Based Medicine Taskforce. A Patient/Population, Intervention, Comparison/Control, Outcome process was used to generate preliminary statements and recommendations to address various aspects related to cardiac surgery in children with trisomy 13 or trisomy 18. Delphi methodology was then used iteratively to generate consensus among the group using a structured communication process.

RESULTS

Nine recommendations were developed from a set of initial statements that arose from the Patient/Population, Intervention, Comparison/Control, Outcome process methodology following the groups' review of more than 500 articles. These recommendations were adjudicated by this group of experts using a modified Delphi process in a reproducible fashion and make up the current publication. The Class (strength) of recommendations was usually Class IIa (moderate benefit), and the overall level (quality) of evidence was level C-limited data.

CONCLUSIONS

This is the first set of recommendations collated by an expert multidisciplinary group to address specific issues around indications for surgical intervention in children with trisomy 13 or trisomy 18 with congenital heart defect. Based on our analysis of recent data, we recommend that decisions should not be based solely on the presence of trisomy but, instead, should be made on a case-by-case basis, considering both the severity of the baby's heart disease as well as the presence of other anomalies. These recommendations offer a framework to assist parents and clinicians in surgical decision making for children who have trisomy 13 or trisomy 18 with congenital heart defect.

Human Genetics of Congenital Heart Defects

Congenital heart diseases (or congenital heart defects/disorders; CHDs) are structural abnormalities of the heart and/or great vessels that are present at birth. CHDs include an extensive range of defects that may be minor and require no intervention or may be life-limiting and require complex surgery shortly after birth. This chapter reviews the current knowledge on the genetic causes of CHD.

The common trisomy syndromes, their cardiac implications, and ethical considerations in care

PURPOSE OF REVIEW

To review the incidence of congenital heart disease in the trisomies, highlight the history of cardiac surgery in trisomy 21 comparing it to the increase in cardiac surgery in trisomies 13 and 18, discuss ethical issues specific to trisomies 13 and 18, and suggest a pathway of shared decision-making in the management of congenital heart disease in trisomy 13 and 18, specifically congenital heart surgery.

RECENT FINDINGS

Congenital heart disease is prevalent in the trisomies and the management of these defects, especially surgical intervention, has changed. In the late 20th century, survival after cardiac surgery in trisomy 21 vastly improved, significantly decreasing morbidity and mortality secondary to pulmonary hypertension. Similarly, procedures and surgeries have been performed with increasing frequency in trisomy 13 and 18 patients and concomitantly, survival in this patient population is increasing. Yet across the United States, the willingness to perform cardiac surgery in trisomy 13 and 18 is variable, and there is ethical controversy about the correct action to take. To address this concern, a shared decision-making approach with an informed parent(s) is advised.

SUMMARY

As the care and management of congenital heart disease changed in trisomy 21, so too it has with trisomy 13 and 18. Physicians and parents should develop goal-directed treatment plans balancing the risk versus benefit and consider cardiac surgical repair if feasible and beneficial.

Survival Outcomes of Two-Stage Intracardiac Repair in Large Ventricular Septal Defect and Trisomy 18

BACKGROUND

Surgical management has not been encouraged in patients with trisomy 18 (T18) and congenital heart diseases due to poor survival. This study aimed to investigate (1) the appropriateness of palliative surgeries followed by intracardiac repair (ICR) (i.e., two-stage ICR) for patients with a large ventricular septal defect (VSD) and T18, and (2) its impact on their long-term outcomes.

METHODS

Medical charts of patients with VSD and T18 who underwent two-stage ICR at the Japanese Red Cross Medical Center between January 2005 and December 2019 were retrospectively reviewed. Demographic data, timing, and types of palliative surgeries, information related to ICR, peri- and postoperative clinical information, postoperative survival, and cause of death were collected. The long-term prognosis of patients treated with two-stage ICR was compared with that of patients treated with primary ICR and palliative surgery without ICR.

RESULTS

Overall, 18 (2 male, 16 female) patients underwent two-stage ICR. Pulmonary artery banding was the initial palliative surgery in all patients after a median duration of 19.5 (range 6-194) days of life. The median age and the mean body weight at the time of ICR were 18.2 (7.6-50.7) months and 6.0 ± 1.0 kg, respectively. The mean pulmonary artery pressure and pulmonary vascular resistance index before ICR were 19.1 ± 7.3 mmHg and 3.4 ± 2.0 U m², respectively. Overall, 17/18 (94%) patients were discharged after ICR. Fourteen (78%) patients were alive during data collection. None of the patients died of cardiac insufficiency, and the median duration of survival was 46.3 (14.3-186.4) months since birth. Most patients required cardiac medications rather than pulmonary vasodilators at the last follow-up. During the study period, three patients underwent primary ICR, and 46 underwent palliative surgery without ICR. Of those who underwent primary ICR, two died in the hospital on the first and 48^th day following ICR, and the third died 179 days after the ICR. The Log-rank test revealed a significantly longer survival for the patients treated with two-stage ICR compared with those treated with palliative surgery without ICR (P = 0.003).

CONCLUSION

Two-stage ICR improves the long-term survival of patients with VSDs and T18. This safe surgical strategy can also prevent pulmonary hypertension in such patients.

Congenital polyvalvular disease expands the cardiac phenotype of the RASopathies

The RASopathies are a group of similar genetic syndromes with cardiovascular abnormalities, characteristic facial features, short stature, abnormalities of the skin and musculoskeletal system, and variable neurodevelopmental challenges. The most common cardiovascular abnormalities include pulmonary valvular stenosis and hypertrophic cardiomyopathy. Congenital polyvalvular disease (CPVD) refers to congenital dysplasia of two or more cardiac valves. We diagnosed a RASopathy in two individuals with CPVD and noted that CPVD in RASopathies has rarely been reported in the literature. Thus, we performed a retrospective chart review and literature review to investigate the association and characterize the phenotype of CPVD in the RASopathies. CPVD was present in 2.5% (n = 6/243) of individuals in our RASopathy cohort. Involvement of two cardiac valves, commonly the aortic and pulmonic valves, was seen in the majority of individuals (6/8; 75%) in our cohort, but only 27% (3/11) of reported CPVD and RASopathy cases in the literature. CPVD should be considered an associated cardiovascular phenotype of the RASopathies, which has implications for diagnosis and management.

Insufficient development of vessels and alveoli in lungs of infants with trisomy 18-Features of pulmonary histopathological findings from lung biopsy

The aim of this study was to evaluate the features of pulmonary histopathological changes in cases of trisomy 18 complicated with congenital heart disease and pulmonary arterial hypertension. Twenty-eight patients with trisomy 18 underwent open lung biopsy at the time of primary operation in our hospital between 2008 and 2019. We compared these histopathological findings with those from previously described groups without trisomy 18. Mean age at primary cardiac surgery was 37 days (range, 9-69 days). According to the Heath-Edwards (HE) classification, 1, 8, 12, and 5 patients were graded as 0, 1, 2, and 3, respectively, whereas 2 patients were not classifiable due to medial defects in the small pulmonary arteries (MD). Four (14.3%) and 13 (46.4%) patients presented with MD and hypoplasia of the small pulmonary arteries (HS). Fifteen (53.6%) and 21 (75.0%) patients presented with alveolar hypoplasia (AH) and alveolar wall thickening (AT). MD, HS, and AH in trisomy 18 were present frequently, differing significantly from previous reports. These findings might be associated with congenital inadequate development of vessels and alveoli in the lung, contributing to a high risk of PAH in trisomy 18.

Interdisciplinary care of children with trisomy 13 and 18

Children with trisomy 13 and 18 (previously deemed "incompatible with life") are living longer, warranting a comprehensive overview of their unique comorbidities and complex care needs. This Review Article provides a summation of the recent literature, informed by the study team's Interdisciplinary Trisomy Translational Program consisting of representatives from: cardiology, cardiothoracic surgery, neonatology, otolaryngology, intensive care, neurology, social work, chaplaincy, nursing, and palliative care. Medical interventions are discussed in the context of decisional-paradigms and whole-family considerations. The communication format, educational endeavors, and lessons learned from the study team's interdisciplinary care processes are shared with recognition of the potential for replication and implementation in other care settings.

Genetic Basis of Human Congenital Heart Disease

Congenital heart disease (CHD) is the most common major congenital anomaly with an incidence of ∼1% of live births and is a significant cause of birth defect-related mortality. The genetic mechanisms underlying the development of CHD are complex and remain incompletely understood. Known genetic causes include all classes of genetic variation including chromosomal aneuploidies, copy number variants, and rare and common single-nucleotide variants, which can be either de novo or inherited. Among patients with CHD, ∼8%-12% have a chromosomal abnormality or aneuploidy, between 3% and 25% have a copy number variation, and 3%-5% have a single-gene defect in an established CHD gene with higher likelihood of identifying a genetic cause in patients with nonisolated CHD. These genetic variants disrupt or alter genes that play an important role in normal cardiac development and in some cases have pleiotropic effects on other organs. This work reviews some of the most common genetic causes of CHD as well as what is currently known about the underlying mechanisms.

Congenital Heart Disease: Prenatal Diagnosis and Genetic Associations

Importance

Congenital heart disease (CHD) is a common cause of neonatal morbidity and mortality. Several genetic abnormalities have been linked to congenital cardiac disease. When diagnosed prenatally, appropriate evaluation can help optimize neonatal outcomes.

Objective

The objective of this review is to identify appropriate prenatal genetic testing when congenital cardiac defects are identified antenatally. This review also identifies specific congenital cardiac defects that are associated with fetal aneuploidy and genetic syndromes.

Evidence Acquisition

A MEDLINE search of "genetic testing" or "microarray" and "congenital heart disease" and specific conditions reported in the review was performed.

Results

The evidence cited in this review includes case reports or case series (4) textbooks (3), systematic reviews (1), expert committee opinions (10), and 37 additional peer-reviewed journal articles that were original research or expert summaries.

Conclusions and Relevance

When CHD is identified through prenatal screening, patients should be referred for genetic counseling and offered appropriate genetic testing. Prenatal diagnosis of genetic syndromes related to CHD and close communication between obstetric, genetic, and pediatric providers can help optimize outcomes for both mother and baby.

Mixed method study of quality of life for children with trisomy 18 and 13 after cardiac surgery

BACKGROUND AND OBJECTIVES

Cardiac surgical interventions for children with trisomy 18 and trisomy 13 remain controversial, despite growing evidence that definitive cardiac repair prolongs survival. Understanding quality of life for survivors and their families therefore becomes crucial. Study objective was to generate a descriptive summary of parental perspectives on quality of life, family impact, functional status, and hopes for children with trisomy 18 and trisomy 13 who have undergone heart surgery.

METHODS

A concurrent mixed method approach utilising PedsQL™ 4.0 Generic Core Parent Report for Toddlers or the PedsQL™ Infant Scale, PedsQL™ 2.0 Family Impact Module, Functional Status Scale, quality of life visual analogue scale, and narrative responses for 10 children whose families travelled out of state to access cardiac surgery denied to them in their home state due to genetic diagnoses.

RESULTS

Parents rated their child's quality of life as 80/100, and their own quality of life as 78/100 using validated scales. Functional status was rated 11 by parents and 11.6 by providers (correlation 0.89). On quality of life visual analogue scale, all parents rated their child's quality of life as "high" with mean response 92.7/100. Parental hopes were informed by realistic perspective on prognosis while striving to ensure their children had access to reaching their full potential. Qualitative analysis revealed a profound sense of the child's relationality and valued life meaning.

CONCLUSION

Understanding parental motivations and perceptions on the child's quality of life has potential to inform care teams in considering cardiac interventions for children with trisomy 18 and trisomy 13.

Analysis of the genomic expression profile in trisomy 18: insight into possible genes involved in the associated phenotypes

Trisomy 18, sometimes called Edwards syndrome, occurs in about 1 in 6000 live births and causes multiple birth defects in affected infants. The extra copy of chromosome 18 causes the altered expression of many genes and leads to severe skeletal, cardiovascular and neurological systems malformations as well as other medical problems. Due to the low rate of survival and the massive genetic imbalance, little research has been aimed at understanding the molecular consequences of trisomy 18 or considering potential therapeutic approaches. Our research is the first study to characterize whole-genome expression in fibroblast cells obtained from two patients with trisomy 18 and two matched controls, with follow-up expression confirmation studies on six independent controls. We show a detailed analysis of the most highly dysregulated genes on chromosome 18 and those genome-wide. The identified effector genes and the dysregulated downstream pathways provide hints of possible genotype-phenotype relationships to some of the most common symptoms observed in trisomy 18. We also provide a possible explanation for the sex-specific differences in survival, a unique characteristic of trisomy 18. Our analysis of genome-wide expression data moves us closer to understanding the molecular consequences of the second most common human autosomal trisomy of infants who survive to term. These insights might also translate to the understanding of the etiology of associated birth defects and medical conditions among those with trisomy 18.

Congenital heart defects associated with aneuploidy syndromes: New insights into familiar associations

The frequent occurrence of congenital heart defects (CHDs) in chromosome abnormality syndromes is well-known, and among aneuploidy syndromes, distinctive patterns have been delineated. We update the type and frequency of CHDs in the aneuploidy syndromes involving trisomy 13, 18, 21, and 22, and in several sex chromosome abnormalities (Turner syndrome, trisomy X, Klinefelter syndrome, 47,XYY, and 48,XXYY). We also discuss the impact of noninvasive prenatal screening (mainly, cell-free DNA analysis), critical CHD screening, and the growth of parental advocacy on their surgical management and natural history. We encourage clinicians to view the cardiac diagnosis as a "phenotype" which supplements the external dysmorphology examination. When detected prenatally, severe CHDs may influence decision-making, and postnatally, they are often the major determinants of survival. This review should be useful to geneticists, cardiologists, neonatologists, perinatal specialists, other pediatric specialists, and general pediatricians. As patients survive (and thrive) into adulthood, internists and related adult specialists will also need to be informed about their natural history and management.

Congenital Heart Surgical Admissions in Patients with Trisomy 13 and 18: Frequency, Morbidity, and Mortality

Congenital heart defects are common among patients with trisomy 13 and 18; surgical repair has been controversial and rarely studied. We aimed to assess the frequency of cardiac surgery among admissions with trisomy 13 and 18, and evaluate their associations with resource use, complications, and mortality compared to admissions without these diagnoses. We evaluated congenital heart surgery admissions of ages < 18 years in the 1997, 2000, 2003, 2006, and 2009 Kids' Inpatient Database. Bivariate and multivariate analyses examined the adjusted association of trisomy 13 and 18 on resource use, complications, and inpatient death following congenital heart surgery. Among the 73,107 congenital heart surgery admissions, trisomy 13 represented 0.03% (n = 22) and trisomy 18 represented 0.08% (n = 58). Trisomy 13 and 18 admissions were longer; trisomy 13: 27 days vs. 8 days, p = 0.003; trisomy 18: 16 days vs. 8 days, p = 0.001. Hospital charges were higher for trisomy 13 and 18 admissions; trisomy 13: $160,890 vs. $87,007, p = 0.010; trisomy 18: $160,616 vs. $86,999, p < 0.001. Trisomy 18 had a higher complication rate: 52% vs. 34%, p < 0.006. For all cardiac surgery admissions, mortality was 4.5%; trisomy 13: 14% and trisomy 18: 12%. In multivariate analysis, trisomy 18 was an independent predictor of death: OR 4.16, 95% CI 1.35-12.82, p = 0.013. Patients with trisomy 13 and 18 represent 0.11% of pediatric congenital heart surgery admissions. These patients have a 2- to 3.4-fold longer hospital stay and double hospital charges. Patients with trisomy 18 have more complications and four times greater adjusted odds for inpatient death.

Mortality and Resource Use Following Cardiac Interventions in Children with Trisomy 13 and Trisomy 18 and Congenital Heart Disease

We sought to evaluate the mortality, risk factors for mortality, and resource utilization following cardiac interventions in trisomy 13 (T13) and 18 (T18) children. All T13 and T18 children who underwent a cardiac intervention from January 1999 to March 2015 were identified from the Pediatric Health Information System database. Data collected included demographics, type of congenital heart disease (CHD), cardiac interventions, comorbidities, length of stay (LOS), hospital charges, and deaths (within 30 days). Logistic regression analysis was used to determine factors associated with mortality. There were 49 (47% females) T13 and 140 (67% females) T18 subjects. The two cohorts were similar in distribution for race, geographic region, insurance type, and median household income. The most common CHD in both groups was a shunt lesion followed by conotruncal defects. Compared to T18, the T13 cohort had higher mortality (29% vs. 12%), tracheostomies (12% vs. 4%), gastrostomies (18% vs. 6%), and overall resource use (P < 0.05 for all). White race (OR 0.23, 95% CI 0.06-0.81) in T13 and older age (in weeks) at surgery in T18 (OR 0.75, 95% CI 0.64-0.86) were associated with lower mortality. A select group of T13 and T18 CHD patients can undergo successful cardiac interventions, albeit with a higher mortality and resource use. T13 patients have higher mortality and resource use compared to T18. In T13 and T18 patients, interventions for CHD may be an acceptable and ethical option following a careful individualized selection and counseling by a team of experts.

Factors Influencing Outcomes After Cardiac Intervention in Infants with Trisomy 13 and 18

Cardiac intervention remains controversial in patients with trisomy 13 and 18 and little is known about factors that may affect outcomes. The goal of this study was to evaluate preoperative factors and surgical approach with respect to outcomes in these patients. Patients with congenital heart disease and trisomy 13 or 18 presenting to our institution from 2004 through 2015 were retrospectively reviewed. Patients were grouped into complete intervention, palliated intervention, and non-intervention. Pre-intervention variables, timing and type of intervention, post-intervention outcomes, and survival were recorded and comparisons were made between the groups. Of 34 patients, 18 cardiac interventions were performed. Complete repair was performed in 11(61%) and palliation in 7(39%). Median age for complete repair was 9.2 vs. 1.7 months in palliated patients (p < 0.001) and palliated patients were smaller (median 2.5 vs. 5.2 kg, p < 0.001). All patients who underwent complete repair survived to discharge compared to only 57% of patients that were palliated (p = 0.04). Palliated patients had longer intubation and time to discharge (p < 0.05). Survival at last follow-up was greater in the complete repair group compared with palliated patients and non-intervention patients (72, 14, and 18%, p = 0.009) with a longer median length of survival in the complete repair group (p = 0.002). In our group of trisomy 13 and 18 patients, those able to undergo complete repair had improved outcomes. Patients undergoing complete repair were older and bigger; this suggests that delaying intervention and optimizing the likelihood of complete repair may be beneficial.

Sinus of Valsalva Aneurysm in a Patient With Mosaic Trisomy 13: Case Report and Brief Review of the Literature

This report describes a unique case involving an obese 16-year-old boy with a mosaic form of trisomy 13 and no previous cardiac history who presented with a new murmur, hypertension, pleural effusions, and congestive heart failure in the context of sore throat and fever. Evaluation revealed a diagnosis of ruptured noncoronary sinus of Valsalva (SOV) aneurysm. The diagnosis and surgical management of a ruptured noncoronary SOV aneurysm in a pediatric patient are briefly outlined. An SOV aneurysm is an anatomic dilation of one of the sinuses of the aortic root. Aneurysmal dilation occurs more commonly in the right aortic sinus (70%-80%), compared to the noncoronary sinus (23%-25%), and more rarely the left coronary sinus (5%). Rupture of these aneurysms has been reported to be both spontaneous and secondary to physical exertion, hypertension, or trauma. Signs of rupture include a continuous murmur, patients may present with chest pain or with symptoms of acute congestive heart failure. Diagnosis, in this case, was made by transthoracic echocardiography with careful interpretation of color Doppler images.

Genetics of Congenital Heart Disease: Past and Present

Congenital heart disease is the most common congenital anomaly, representing an important cause of infant morbidity and mortality. Congenital heart disease represents a group of heart anomalies that include septal defects, valve defects, and outflow tract anomalies. The exact genetic, epigenetic, or environmental basis of congenital heart disease remains poorly understood, although the exact mechanism is likely multifactorial. However, the development of new technologies including copy number variants, single-nucleotide polymorphism, next-generation sequencing are accelerating the detection of genetic causes of heart anomalies. Recent studies suggest a role of small non-coding RNAs, micro RNA, in congenital heart disease. The recently described epigenetic factors have also been found to contribute to cardiac morphogenesis. In this review, we present past and recent genetic discoveries in congenital heart disease.

Whole Exome Sequencing, Familial Genomic Triangulation, and Systems Biology Converge to Identify a Novel Nonsense Mutation in TAB2-encoded TGF-beta Activated Kinase 1 in a Child with Polyvalvular Syndrome

OBJECTIVE

To use whole exome sequencing (WES) of a family trio to identify a genetic cause for polyvalvular syndrome.

METHODS AND RESULTS

A male child was born with mild pulmonary valve stenosis and mild aortic root dilatation, and an atrial septal defect, ventricular septal defect, and patent ductus arteriosus that were closed surgically. Subsequently, the phenotype of polyvalvular syndrome with involvement of both semilunar and both atrioventricular valves emerged. His family history was negative for congenital heart disease. Because of hypotonia, myopia, soft pale skin, joint hypermobility, and mild facial dysmorphism, either Noonan syndrome- or William syndrome-spectrum disorders were suspected clinically. However, chromosomal analysis was normal and commercially available Noonan syndrome and William syndrome genetic tests were negative. Whole exome sequencing of the patient and both parents was performed. Variants were analyzed by sporadic and autosomal recessive inheritance models. A sporadic mutation, annotated as c.1491 T > A, in TAB2, resulting in a nonsense mutation, p.Y497X, in the TAB2-encoded TGF-beta activated kinase 1 (TAK1) was identified as the most likely disease-susceptibility gene. This mutation results in elimination of the terminal 197 amino acids, including the C-terminal binding motif critical for interactions with TRAF6 and TAK1.

CONCLUSIONS

The combination of WES, genomic triangulation, and systems biology has uncovered perturbations in TGF-beta activated kinase 1 signaling as a novel pathogenic substrate for polyvalvular syndrome.

Phenotypic extremes in liveborn monozygotic twins with mosaic Edwards syndrome

Mosaic trisomy 18 (Edwards syndrome) in monozygotic diamniotic liveborn twins is rare. We describe such a case involving preterm male infants. Although both infants had a low percentage of trisomy 18 cells in peripheral blood leucocytes, their varied phenotypic presentation of mosaic trisomy 18 resulted in one twin surviving, with the other twin's demise at 1 month of age. Despite the presence of trisomy 18 in peripheral leucocytes, further analysis of a buccal smear and skin biopsy of the surviving twin did not show evidence of trisomy 18. Establishing such diagnoses in a timely manner is imperative for the child, parents and clinicians. The clinical course of these twins reflects the unpredictable prognosis associated with the diagnosis of mosaic trisomy 18, and emphasises the challenges that can be encountered when counselling parents.

Molecular insight into heart development and congenital heart disease: An update review from the Arab countries

Congenital heart defect (CHD) has a major influence on affected individuals as well as on the supportive and associated environment such as the immediate family. Unfortunately, CHD is common worldwide with an incidence of approximately 1% and consequently is a major health concern. The Arab population has a high rate of consanguinity, fertility, birth, and annual population growth, in addition to a high incidence of diabetes mellitus and obesity. All these factors may lead to a higher incidence and prevalence of CHD within the Arab population than in the rest of the world, making CHD of even greater concern. Sadly, most Arab countries lack appropriate public health measures directed toward the control and prevention of congenital malformations and so the importance of CHD within the population remains unknown but is thought to be high. In approximately 85% of CHD patients, the multifactorial theory is considered as the pathologic basis. The genetic risk factors for CHD can be attributed to large chromosomal aberrations, copy number variations (CNV) of particular regions in the chromosome, and gene mutations in specific nuclear transcription pathways and in the genes that are involved in cardiac structure and development. The application of modern molecular biology techniques such as high-throughput nucleotide sequencing and chromosomal array and methylation array all have the potential to reveal more genetic defects linked to CHD. Exploring the genetic defects in CHD pathology will improve our knowledge and understanding about the diverse pathways involved and also about the progression of this disease. Ultimately, this will link to more efficient genetic diagnosis and development of novel preventive therapeutic strategies, as well as gene-targeted clinical management. This review summarizes our current understanding of the molecular basis of normal heart development and the pathophysiology of a wide range of CHD. The risk factors that might account for the high prevalence of CHD within the Arab population and the measures required to be undertaken for conducting research into CHD in Arab countries will also be discussed.

The trisomy 18 syndrome

The trisomy 18 syndrome, also known as Edwards syndrome, is a common chromosomal disorder due to the presence of an extra chromosome 18, either full, mosaic trisomy, or partial trisomy 18q. The condition is the second most common autosomal trisomy syndrome after trisomy 21. The live born prevalence is estimated as 1/6,000-1/8,000, but the overall prevalence is higher (1/2500-1/2600) due to the high frequency of fetal loss and pregnancy termination after prenatal diagnosis. The prevalence of trisomy 18 rises with the increasing maternal age. The recurrence risk for a family with a child with full trisomy 18 is about 1%. Currently most cases of trisomy 18 are prenatally diagnosed, based on screening by maternal age, maternal serum marker screening, or detection of sonographic abnormalities (e.g., increased nuchal translucency thickness, growth retardation, choroid plexus cyst, overlapping of fingers, and congenital heart defects ). The recognizable syndrome pattern consists of major and minor anomalies, prenatal and postnatal growth deficiency, an increased risk of neonatal and infant mortality, and marked psychomotor and cognitive disability. Typical minor anomalies include characteristic craniofacial features, clenched fist with overriding fingers, small fingernails, underdeveloped thumbs, and short sternum. The presence of major malformations is common, and the most frequent are heart and kidney anomalies. Feeding problems occur consistently and may require enteral nutrition. Despite the well known infant mortality, approximately 50% of babies with trisomy 18 live longer than 1 week and about 5-10% of children beyond the first year. The major causes of death include central apnea, cardiac failure due to cardiac malformations, respiratory insufficiency due to hypoventilation, aspiration, or upper airway obstruction and, likely, the combination of these and other factors (including decisions regarding aggressive care). Upper airway obstruction is likely more common than previously realized and should be investigated when full care is opted by the family and medical team. The complexity and the severity of the clinical presentation at birth and the high neonatal and infant mortality make the perinatal and neonatal management of babies with trisomy 18 particularly challenging, controversial, and unique among multiple congenital anomaly syndromes. Health supervision should be diligent, especially in the first 12 months of life, and can require multiple pediatric and specialist evaluations.

The pathogenesis of atrial and atrioventricular septal defects with special emphasis on the role of the dorsal mesenchymal protrusion

Partitioning of the four-chambered heart requires the proper formation, interaction and fusion of several mesenchymal tissues derived from different precursor populations that together form the atrioventricular mesenchymal complex. This includes the major endocardial cushions and the mesenchymal cap of the septum primum, which are of endocardial origin, and the dorsal mesenchymal protrusion (DMP), which is derived from the Second Heart Field. Failure of these structures to develop and/or fully mature results in atrial septal defects (ASDs) and atrioventricular septal defects (AVSD). AVSDs are congenital malformations in which the atria are permitted to communicate due to defective septation between the inferior margin of the septum primum and the atrial surface of the common atrioventricular valve. The clinical presentation of AVSDs is variable and depends on both the size and/or type of defect; less severe defects may be asymptomatic while the most severe defect, if untreated, results in infantile heart failure. For many years, maldevelopment of the endocardial cushions was thought to be the sole etiology of AVSDs. More recent work, however, has demonstrated that perturbation of DMP development also results in AVSD. Here, we discuss in detail the formation of the DMP, its contribution to cardiac septation and describe the morphological features as well as potential etiologies of ASDs and AVSDs.

Prenatal diagnosis of mobile flap-like tissue on the ventricular septal defect in a newborn with trisomy 18

Trisomy 18 is the second most common autosomal trisomy in liveborn infants. Various congenital malformations, mental retardation, and high rate of infant mortality in the first year of life are characteristic features of trisomy 18. Congenital heart disease occurs in over 90% of these patients and the most common cardiac lesions are ventricular septal defect, patent ductus arteriosus and atrial septal defect. This is a case report of a baby born with trisomy 18 (postnatal diagnosis) in whom there was an unusual echocardiographic appearance of a mobile structure ("flap-like") around the area of a VSD-which was imaged prenatally.

Pediatric sub-specialist controversies in the treatment of congenital heart disease in trisomy 13 or 18

Trisomy 13 and 18 are associated with congenital heart disease. Cardiac palliation has been reported in the literature, but is not usually done in this population. Thus, a multi-disciplinary team may experience controversy in formulating a care plan that includes cardiac intervention. Our objective was to determine differences in recommendations for cardiac intervention in this population between physicians specializing in pediatric cardiac critical care, neonatology, and genetics. A web-based survey was performed between April 2007 and August 2008. This survey evaluated surgical and transcatheter cardiac palliations that had been performed for individuals with trisomy 13 or 18 at the respondent's institution, the respondent's recommendations for cardiac intervention in hypothetical symptomatic patients with trisomy 13 or trisomy 18 and the influence of parental preference on these recommendations. Eight hundred fifty-nine responses were obtained from a primarily academic practice setting (59%). Cardiologists were most likely to recommend intervention; low risk interventions were recommended by 32% of cardiologists, 7% of neonatologists and 20% of geneticists. Parental request to intervene resulted in a 3 fold increased in the likelihood of all specialist recommending intervention. Counseling of families frequently occurred by multiple sub specialists (50%) and there was frequently (71%) a difference in opinion. Individuals with trisomy 13 or 18 are receiving cardiac intervention at many institutions. Cardiologists were more likely than geneticists or neonatologists to recommend intervention on all heart lesions other than single ventricle palliation which no specialists recommended. Parental wishes that "everything be done" significantly influenced all specialists' recommendations.

Investigating 22q11.2 deletion and other chromosomal aberrations in fetuses with heart defects detected by prenatal echocardiography

Congenital heart disease (CHD) is the most common birth defect and the leading cause of mortality in the first year of life. In fetuses with a heart defect, chromosomal abnormalities are very frequent. Besides aneuploidy, 22q11.2 deletion is one of the most recognizable chromosomal abnormalities causing CHD. The frequency of this abnormality varies in nonselected populations. This study aimed to investigate the incidence of the 22q11.2 deletion and other chromosomal alterations in a Brazilian sample of fetuses with structural cardiac anomalies detected by fetal echocardiography. In a prospective study, 68 fetuses with a heart defect were evaluated. Prenatal detection of cardiac abnormalities led to identification of aneuploidy or structural chromosomal anomaly in 35.3% of these cases. None of the fetuses with apparently normal karyotypes had a 22q11.2 deletion. The heart defects most frequently associated with chromosomal abnormalities were atrioventricular septal defect (AVSD), ventricular septal defect (VSD), and tetralogy of Fallot. Autosomal trisomies 18 and 21 were the most common chromosomal abnormalities. The study results support the strong association of chromosome alterations and cardiac malformation, especially in AVSD and VSD, for which a chromosome investigation is indicated. In fetuses with an isolated conotruncal cardiopathy, fluorescence in situ hybridization (FISH) to investigate a 22q11.2 deletion is not indicated.

Cardiac surgery in patients with trisomy 18

Cardiac surgery is infrequently but increasingly being used to repair congenital heart defects associated with trisomy 18. The clinical details of trisomy 18 patients undergoing cardiac surgery have rarely been reported. Seventeen patients with trisomy 18 and serious cardiac symptoms underwent cardiac surgery in our institution. Age at surgery ranged from 7 to 258 days (median, 66 days). One patient had an atrioventricular septal defect and coarctation of the aorta. The remaining patients had ventricular septal defects, including four patients with coarctation of the aorta. Fourteen patients had associated patent ductus arteriosus. Fourteen patients underwent palliative surgery without cardiopulmonary bypass, and four of these underwent a second-stage intracardiac repair. The other three patients underwent primary intracardiac repair. Postoperatively, 14 patients (82%) were discharged home with improved symptoms. Survival from birth ranged from 12 to 1384 days (median, 324 days). Eight patients survived longer than 1 year. Median postoperative survival was 179 days. Postoperative survival was significantly better after palliative surgery (0 to 1239 days; median, 257 days) than after primary intracardiac repair (1 to 179 days; median, 48 days). Only one patient died of heart failure, suggesting that cardiac surgery was effective in preventing heart failure-related death.

Intensive cardiac management in patients with trisomy 13 or trisomy 18

Intensive cardiac management such as pharmacological intervention for ductal patency (indomethacin and/or mefenamic acid for closure and prostaglandin E1 for maintenance) and palliative or corrective surgery is a standard treatment for congenital heart defects. However, whether it would be a treatment option for children with trisomy 13 or trisomy 18 syndrome is controversial because the efficacy on survival in patients with these trisomies has not been evaluated. We retrospectively reviewed 31 consecutive neonates with trisomy 13 or trisomy 18 admitted to our neonatal ward within 6 hr of birth between 2000 and 2005. The institutional management policies differed during three distinct periods. In the first period, both pharmacological ductal intervention and cardiac surgery were withheld. In the second, pharmacological ductal intervention was offered as an option, but cardiac surgery was withheld. Both strategies were available during the third period. The median survival times of 13, 9, and 9 neonates from the first, second, and third periods were 7, 24, and 243 days, respectively. Univariate and multivariate analyses confirmed that the patients in the third period survived significantly longer than the others. Intensive cardiac management consisting of pharmacological intervention for ductal patency and cardiac surgery was demonstrated to improve survival in patients with trisomy 13 or trisomy 18 in this series. Therefore, we suggest that this approach is a treatment option for cardiac lesions associated with these trisomies. These data are helpful for clinicians and families to consider in the optimal treatment of patients with these trisomies.

Congenital diaphragmatic hernia and associated cardiovascular malformations: type, frequency, and impact on management

The co-occurrence of congenital diaphragmatic hernia (CDH) and cardiovascular malformations (CVMs) has important clinical, genetic, and developmental implications. Previous examinations of this topic often included patients with genetic syndromes. To correct this potential bias, we undertook an extensive review of the literature and obtained new data. The frequency of CVMs associated with isolated CDH was 11-15%. A careful analysis of CVMs indicates that atrial and ventricular septal defects, conotruncal defects, and left ventricular outflow tract obstructive defects were the most common type of CVMs, but proportional to the frequency of occurrence in the general population. The combination of CVM and CDH results in a poorer prognosis than would be expected with either malformation alone. However, the impact on survival from patients with a genetic syndrome has not been consistently evaluated. We encourage researchers to re-analyze existing series and recommend that future studies distinguish isolated CDH from that which is associated with other malformations, especially as part of genetic syndromes. Therapies should be tailored to maximize cardiac output and systemic oxygen delivery rather than systemic oxygen saturation alone. Although there is speculation about the frequency with which isolated left ventricular "hypoplasia" occurs in patients with CDH, we suggest it results from compression of a pre-load deficient left ventricle by the hypertensive right ventricle, and unlike true hypoplasia, is reversible. Irrespective of the type of severity of CVMs in patients with CDH, the degree of pulmonary hypoplasia and pulmonary vascular disease predicts outcome.

Clinical characteristics and survival of trisomy 13 in a medical center in Taiwan, 1985-2004

BACKGROUND

This study investigated the survival and natural history of trisomy 13 in a series of patients, comparing the management and outcome before and after the implementation of Taiwan's National Health Insurance program (NHI).

METHODS

A total of 28 cases of trisomy 13 seen at Mackay Memorial Hospital, Taipei, Taiwan, from 1985 to 2004 were retrospectively reviewed. Survival and management before (12 cases) and after (16 cases) the implementation of National Health Insurance were compared, and structural defects, imaging findings, and cytogenetic results were analyzed. The cases that were diagnosed prenatally, and finally terminated, were excluded from this study. The diagnosis of trisomy 13 was based on the postnatal chromosome analysis.

RESULTS

All patients except one with trisomy 13 translocation died in their first year because of severe malformations of the cardiovascular or central nervous system. The median survival was 9 days. After implementation of National Health Insurance, survival with trisomy 13 was significantly longer than before (P < 0.05). The three most common structural defects were abnormal auricular helices or low-set ears (89%), cryptorchidism and abnormal scrotum of male (73%) and cleft lip and/or palate (71%). Using echocardiography, the most commonly detected heart defects were patent ductus arteriosus (68%), ventricular septal defect (50%) and atrial septal defect (50%), and eight cases (36%) had complex congenital heart defects. The most common brain lesion was lenticulostriate vasculopathy (22%), followed by holoprosencephaly (17%), brain edema (13%) and subependymal cyst (13%).

CONCLUSIONS

Early diagnosis and the survival patterns from the data collected should be used to inform parents and health-care professionals to assist in decision making. Although most patients with trisomy 13 die within the first weeks after birth, it is important to recognize that a few may survive the first year. When counseling families, the long-term survival prospects of trisomy 13 patients should be included.

Trisomy 18 in neonates: prenatal diagnosis, clinical features, therapeutic dilemmas and outcome

The study aimed to analyse the clinical courses of aggressively treated neonates with cytogenetically confirmed trisomy 18, with special attention focused on the efficiency of prenatal diagnostics, associated malformations, therapeutic dilemmas and outcomes. We investigated retrospectively the data concerning 20 neonates with trisomy 18, admitted to the Neonatal Intensive Care Unit (NICU) in Katowice between January 2000 and February 2005. Their birth weights ranged from 650 g to 2400 g, mean 1812 g; gestational age ranged from 27 to 42 weeks, median 38 weeks. Intrauterine growth retardation was noticed in 90% of neonates. Trisomy 18 was suspected prenatally in 40% of cases. Most (80%) of newborns were delivered by caesarean section (92% of neonates with prenatally unrecognized chromosomal defects, 62% of neonates with trisomy 18 suspicion) and 70% of infants needed respiratory support immediately after birth. Cardiac defects were present in 95%, central nervous system malformations in 65%, severe anomalies of digestive system or abdominal wall in 25% of patients. Nine surgical operations were performed during hospitalization (4 were palliative cardiac surgeries). Six patients (30%) survived the neonatal period and were discharged from the NICU. The median survival of the neonates who died was 20 days. In 4 cases cardiac problems implicated their death; in others, deaths were attributed to multiorgan failure, prematurity and/or infection. Further improvement of efficiency of prenatal ultrasound screening for diagnosis of trisomy 18 in the fetus is necessary. A lack of prenatal diagnosis of trisomy 18 in the fetus results in a high rate of unnecessary caesarean sections in these pregnancies. Despite the aggressive treatment most neonates with trisomy 18 died during the neonatal period. The majority of deaths were attributed to cardiorespiratory and multiorgan failure. Concerning the poor prognosis, prompt karyotyping (using FISH) of clinically suspected trisomy 18 is very important, because many invasive procedures and surgeries may then be avoided.

Congenital malformations among liveborn infants with trisomies 18 and 13

Trisomy 18 and trisomy 13 are associated with serious and/or fatal birth defects, with death frequently occurring in the first month of life. Previous studies are limited by small samples and are dated. This study characterized the comorbid birth defects associated with trisomy 18 and trisomy 13 among US liveborn infants using the Healthcare Cost and Utilization Project's Kids' Inpatient Database and Nationwide Inpatient Sample, two large, current and nationally representative databases. The occurrence of 39 commonly reported comorbid birth defects among infants with trisomies 18 and 13 was compared to the occurrence of malformations among newborns without trisomies. The prevalences of trisomy 18 and 13 were 1.29/10,000 and 0.85/10,000 live births, respectively. Among infants with trisomy 18, 61% were female, 45.4% with heart defects. Among those with trisomy 13, 53% were female, 38.4% had heart defects, 24.5% had orofacial anomalies, and 11.2% had central nervous system abnormalities. More than half of the newborns with both conditions died prior to discharge. This updated information can be used to inform clinical decision-making and may help providers better prepare families for infants with trisomies.

Neonatal management of trisomy 18: Clinical details of 24 patients receiving intensive treatment

Management of neonates with trisomy 18 is controversial, supposedly due to the prognosis and the lack of precise clinical information concerning efficacy of treatment. To delineate the natural history of trisomy 18 managed under intensive treatment, we reviewed detailed clinical data of 24 patients with full trisomy 18 admitted to the neonatal intensive care unit of Nagano Children's Hospital, providing intensive treatment to those with trisomy 18, from 1994 to 2003. Cesarean, resuscitation by intubation, and surgical operations were performed on 16 (67%), 15 (63%), and 10 (42%) of the patients, respectively. Mechanical ventilation was required by 21 (88%), and 6 (29%) of them were extubated. Survival rate at age 1 week, 1 month, and 1 year was 88%, 83%, and 25%, respectively. Median survival time was 152.5 days. Respiration was not stabilized in two patients with left diaphragmatic eventration and hypoplasia accompanied by lung hypoplasia, even with maximal ventilation. The common underlying factors associated with death were congenital heart defects and heart failure (96%), followed by pulmonary hypertension (78%). The common final modes of death were sudden cardiac or cardiopulmonary arrest (26%) and possible progressive pulmonary hypertension-related events (26%). These data of improved survival, through neonatal intensive treatment, are helpful for clinicians to offer the best information on treatment options to families of patients with trisomy 18.

Clinical characteristics and survival of trisomy 18 in a medical center in Taipei, 1988–2004

Trisomy 18 is the second most common autosomal trisomy in newborns. The birth prevalence of this disorder is approximately 1 in 3,000 to 1 in 8,000, and the life span of the majority of patients is less than 1 year. As information regarding outcome in trisomy 18 is rather fragmentary in the literature, this study is aimed at investigating the survival and natural history of trisomy 18. We also evaluated the survival age and management of trisomy 18 in two different periods, before and after the implementation of National Health Insurance (NHI) program. Thirty-nine cases of trisomy 18 were collected in Mackay Memorial Hospital in a 17-year period, from 1988 to 2004. Delivery data, survival age, management before and after the implementation of NHI program, structural defects, image findings and cytogenetic results were analyzed by medical and nurse's records. The diagnosis of trisomy 18 was based on the prenatal amniocentesis or postnatal chromosome analysis. Three patients had trisomy 18 mosaicism. Since cardiovascular and central nervous systems are the most common organ systems involved in this disorder, 31 patients received brain ultrasonography and heart ultrasonography for evaluation of their multiple anomalies after admission. All patients except one died in their first year due to severe malformations of the cardiovascular or central nervous systems. The median survival age was 6 days. We found a longer survival with female patients than with male patients (P < 0.05). Implementation of NHI program in the more recent decade of this study period was associated with longer survival of trisomy 18 (P < 0.05). The three most common structural defects were clenched hands (95%), rocker bottom feet (90%), and low set or malformed ears (90%). Low birth weight was present in 90%. By cardiac ultrasonography, the top four heart defects were ventricular septal defect (94%), patent ductus arteriosus (77%) and atrial septal defect (68%). However, ten cases (32%) had complex congenital heart defects. By brain ultrasonography, the most common brain lesion was cerebellar hypoplasia (32%), followed by brain edema (29%), enlarged cisterna magna (26%) and choroid plexus cysts (19%). Although most patients with trisomy 18 die within the first few weeks after birth, it is important to recognize that a small but notable percentage of these patients will survive the first year. When prenatal or postnatal decisions need to be made, the possibility of long-term survival should be included in any discussion to enable families to make the most appropriate decision.

Fetal echocardiography in trisomy 18

BACKGROUND

Previously reported pathological series suggest that cardiac malformations are universal in trisomy 18. We examined our experience of fetal echocardiography in trisomy 18 for comparison.

METHODS

Of 255 fetuses with trisomy 18 detected in our centre between January 1999 and June 2004, 174 were evaluated using fetal echocardiography. Our results were compared to four previous echocardiographic and four autopsy series, comprising 89 and 110 patients, respectively.

RESULTS

Of these 174 fetuses, 114 were examined between 10 and 14 weeks gestation and the remainder between 15 and 33 weeks. An increased nuchal translucency measurement was the reason for referral in most of the early cases and extracardiac anomalies in the remainder. Images were non-diagnostic in 12 cases (7%), all examined at <15 weeks gestation. Abnormal cardiac findings were detected in 118 of the remaining 162 fetuses (73%), including 15 with functional anomalies. The various heart malformations included ventricular septal defects, tetralogy of Fallot, left heart disease, and atrioventricular septal defects. In all series used for comparison, a similar diversity of disease was seen. In pathological series of trisomy 18, structural heart malformations were found in all cases, but some had lesions which would not be detectable echocardiographically in the fetus.

CONCLUSION

Abnormal cardiac findings are detectable echocardiographically in the majority of cases of trisomy 18 examined during fetal life, but not in all. A wide spectrum of heart defects is seen. Diagnosis of heart malformations can be made reliably, even in the first trimester at the time of nuchal translucency measurement.

Left ventricular noncompaction cardiomyopathy in association with trisomy 13

In recent years, left ventricular noncompaction (LVNC) has been recognized as a distinct form of cardiomyopathy with its own clinical presentation and natural history. More than 100 cases of LVNC have been described in children. Although LVNC has been described in association with metabolic disorders such as Fabry's disease or genetic disorders such as Roifman's syndrome, this case represents the first report of LVNC in a child with trisomy 13.

Genetics of cardiological disorders

Information generated by work on the human genome means that we now understand the genetic basis of many of the cardiac anomalies that present in the fetal and neonatal periods. This allows for an earlier and more definitive diagnosis of an underlying syndrome, although it does not replace the need for an accurate recognition of clinical signs. The implications of this new information are considered in the context of some of the more frequently encountered conditions with cardiac associations.

Effectiveness of cardiac surgery in trisomies 13 and 18 (from the Pediatric Cardiac Care Consortium)

Because of severely reduced lifespan in children with trisomies 13 and 18, surgical repair of congenital heart lesions has rarely been offered. With data from a multicenter registry, we report 35 cases of cardiac surgery in infants and children with trisomy 13 or 18 with a 91% hospital survival rate. Those patients without an extended preoperative ventilatory requirement did not require prolonged mechanical ventilation after surgery.

Population-based analyses of mortality in trisomy 13 and trisomy 18

OBJECTIVE

Although trisomy 13 and trisomy 18 are generally considered to be lethal, long-term survival of patients has been reported. We sought to evaluate mortality in people with trisomy 13 or 18 using 2 population-based strategies.

METHODS

In the first analysis, infants who had trisomy 13 or 18 and were born during 1968-1999 were identified using the Metropolitan Atlanta Congenital Defects Program, a population-based birth defects surveillance system. Dates of death were documented using hospital records, Georgia vital records, and the National Death Index. In the second analysis, we used the Multiple-Cause Mortality Files compiled from US death certificates from 1979 through 1997. Using these 2 analyses, we examined median survival time or median age at death, survival beyond 1 year of age, and factors associated with longer survival.

RESULTS

Using Metropolitan Atlanta Congenital Defects Program, we identified 70 liveborn infants with trisomy 13 and 114 liveborn infants with trisomy 18. Median survival time was 7 days (95% confidence interval [CI]: 3-15) for people with trisomy 13 and 14.5 days (95% CI: 8-28) for people with trisomy 18. For each condition, 91% of infants died within the first year. Neither race nor gender affected survival for trisomy 13, but for trisomy 18, girls and infants of races other than white seemed to survive longer. The presence of a heart defect did not seem to affect survival for either condition. Using MCMF, we identified 5515 people with trisomy 13 and 8750 people with trisomy 18 listed on their death certificates. Median ages at death for people with trisomy 13 and trisomy 18 both were 10 days; 5.6% of people with trisomy 13 and 5.6% of people with trisomy 18 died at age 1 year or greater. Race and gender seemed to affect survival in both conditions, with girls and blacks showing higher median ages at death.

CONCLUSIONS

Although survival is greatly affected by trisomy 13 and trisomy 18, 5% to 10% of people with these conditions survive beyond the first year of life. These population-based data are useful to clinicians who care for patients with these trisomies or counsel families with infants or fetuses who have a diagnosis of trisomy 13 or 18.

Genetics and cardiac anomalies: the heart of the matter

The recent exponential increase in knowledge in genetics has revolutionized all aspects of medicine. The completion of the first draft of the human genome project has provided for clinicians a range and depth of information never before imagined. Over the last 25 years understanding the anatomical and physiological basis of a number of congenital cardiac anomalies has led to better care and outcome for the patients born with congenital cardiac defects. In the last decade the role of genes, their critical timing of expression, and understanding of important downstream pathways for optimizing normal development and control of the left right asymmetry have emerged. The progress in cardiac genetics has been supplemented by advances in cardiac imaging modalities leading to improvements in diagnosis of the cardiac anomalies. About 30% of all congenital heart diseases are associated with extra- cardiac malformations. Chromosomal anomalies are more common in patients with cardiac anomalies than the general population. Presence of facial dysmorphic features and associated extra-cardiac anomalies should alert the pediatricians to an underlying syndrome diagnosis. Newer molecular cytogenetics techniques such as fluorescence in situ hybridization (FISH) and molecular tests are now routinely utilized for confirming clinical diagnoses. In this review we have summarized clinical features and discussed the genetic basis of several syndromes (for example, 22q11 deletion syndrome, Williams syndrome, Down Syndrome, Kabuki syndrome etc.) where specific cardiac anomalies are frequently encountered. The importance of establishing an accurate clinical diagnosis cannot be over emphasized. The families need genetic counselling with accurate information on the recurrence risks. With the advent of the Internet and rapid access to information, the clinicians and the patient families can access valuable information regarding the prognosis, natural history, and clinical interventions for the affected child, and useful support groups for the family. Detection of cardiac anomalies during antenatal period warrants a genetics assessment.

Congenital heart disease and genetic syndromes: specific correlation between cardiac phenotype and genotype

The increasing role of genetic factors in the etiology of congenital heart defects is shown by the high frequency of genetic syndromes and extracardiac malformations in these patients. The accurate study of cardiac anatomy disclosed that peculiar morphologic subtypes of heart defects are related to specific genetic conditions. The correlation between anatomic cardiac patterns and some genetic anomalies (trisomy, deletion, mutation) suggests that specific morphogenetic mechanisms put in motion by gene(s) can result in a specific cardiac phenotype. In this review we analyze the cardiac morphology and the frequent genetic syndromes in five groups of congenital heart diseases: right-sided obstructions, left-sided obstructions, atrioventricular canal defects, ventricular septal defects, and conotruncal defects. Progress in this field is due not only to new research in molecular biology, but also to the attention of clinicians to a detailed cardiac diagnosis and to specific correlations between genotype and phenotype.

Atrio-ventricular valve dysplasia in 22 newborn infants

We retrospectively studied the experience of our institution with isolated dysplasia of one or both atrio-ventricular valves in 22 newborn infants. All patients with associated cardiac malformations were excluded. Ten patients exhibited isolated tricuspid valve dysplasia. One patient had tricuspid valve dysplasia and a dysplastic pulmonary valve. In 10 patients, both atrio-ventricular valves were affected. Finally, mitral valve dysplasia was associated with pulmonary valve stenosis in 1 case. Associated syndromes and/or chromosomal anomalies were: Down syndrome (n=2), trisomy 18 (n=1), Noonan syndrome (n=1), Marfan syndrome (n=3), Ehlers-Danlos and Cutis laxa (n=2). Mortality was 27.2% during follow-up (mean 51 months): 3 patients with chromosomal aneuploidies, 2 patients with severe neonatal Marfan syndrome and 1 with Ehlers-Danlos. Complications were: sustained supra-ventricular tachycardia in 3, neonatal staphylococcal tricuspid valve endocarditis in 1, persistent significant valvular disease in 8. In the remaining 9 survivors, the dysplasia of the atrio-ventricular valves persists with absent or mild incompetence. Beside obvious chromosomal anomalies, newborn infants with dysplastic valves should be investigated for manifestations of connective tissue disorders. This may help to identify new pleiotropic syndromes which include valvular dysplasia as one manifestation.

Abnormalities of the heart and great arteries in first trimester chromosomally abnormal fetuses

Pathological examination of the heart and great arteries was performed in 112 chromosomally abnormal fetuses after surgical termination of pregnancy at 11-16 weeks of gestation. The chromosomal abnormalities were diagnosed by chorion villus sampling which was carried out because screening of the pregnancies by a combination of maternal age and fetal nuchal translucency thickness at 10-14 weeks of gestation identified them as being at increased risk. The group consisted of 60 fetuses with trisomy 21, 29 with trisomy 18, 17 with trisomy 13 and 6 with Ullrich-Turner syndrome. The most common cardiac lesion seen in trisomy 21 fetuses was an atrioventricular or ventricular septal defect. Trisomy 18 was associated with ventricular septal defects and/or polyvalvular abnormalities. In trisomy 13, there were atrioventricular or ventricular septal defects, valvular abnormalities, and either narrowing of the isthmus or truncus arteriosus. Ullrich-Turner syndrome was associated with severe narrowing of the whole aortic arch. In all four groups of chromosomally abnormal fetuses, the aortic isthmus was significantly narrower than in normal fetuses and the degree of narrowing was significantly greater in fetuses with high nuchal translucency thickness. It is postulated that narrowing of the aortic isthmus may be the basis of increased nuchal translucency thickness in all four chromosomal abnormalities.