Congenital cardiovascular malformations: questions on inheritance. Baltimore-Washington Infant Study Group

Spectrum of congenital heart defects in Croatia

The aim of our study was to investigate the incidence of congenital defects in children born in Croatia during a period of 5 years, its association with extracardiac malformations, its treatment, and outcome. Medical information about the patients was obtained from 14 paediatric cardiology centres that cover the whole country. Diagnosis was made by clinical findings, electrocardiography, chest X-ray, echocardiography, catheterisation, or autopsy. Between October 1, 2002 and October 1, 2007, there were 205,051 live births in Croatia, 1,480 of which were patients diagnosed with congenital heart disease, accounting for 0.72% of the live-born children. The distribution was made up of 34.6% children with ventricular septal defect, 15.9% with atrial septal defect, 9.8% with patency of arterial duct, 4.9% with pulmonary valvar stenosis, 3.3% with tetralogy of Fallot, 3.3% with transposed great arteries, 3.3% with aortic stenosis, 3.2% with aortic coarctation, 4.3% with atrioventricular septal defect and common atrioventricular orifice, 2.3% with hypoplastic left heart syndrome, and 8.3% other with severe defects. The average age in the time of diagnoses is 70.41 days (SD, 188.13), with low average time of diagnoses of severe heart defects, 9.6 days (SD, 32.52). Among patients, 14.5% had chromosomal defects, syndromes, and/or other congenital major anomalies. During the study, 57 patients died because of cardiac anomalies or other related problems, 24 who died were operated. The rates of specific cardiac defects and association with extracardiac malformations are generally comparable with those reported in similar studies. In spite of all problems, mortality rate of 3.85% is low but could be improved.

Variants of folate metabolism genes and risk of left-sided cardiac defects

BACKGROUND

Congenital heart defects (CHDs) are the most common, serious group of birth defects. Although relatively little is known about the causes of these conditions and there are no established prevention strategies, evidence suggests that the risk of CHDs may be related to maternal folate status as well as genetic variants in folate-related genes. Efforts to establish the relationships between these factors and CHD risk have, however, been hampered by a number of factors, including small study sample sizes and phenotypic heterogeneity.

METHODS

The present study examined the relationship between nine genetic variants in eight folate-related genes and a relatively homogeneous group of left-sided cardiac defects in a cohort of 386 case-parent triads. Log-linear analyses were used to assess both maternal and inherited genetic effects.

RESULTS

Analyses of the study data provided marginal evidence that the maternal MTR A2756G (unadjusted p = 0.01) and the inherited BHMT G742A (unadjusted p = 0.06) genotypes influence the risk of this subset of CHDs. However, neither association achieved significance when the false-discovery rate was controlled at 0.05.

CONCLUSIONS

These results, which are based on the largest study sample and most comprehensive assessment of the relationship between left-sided cardiac defects and folate-related genes reported to date, provide little evidence that this subset of CHDs is folate related. However, even larger studies and more comprehensive evaluations of the folate pathway genes are required to fully explore the relationship between folate and left-sided cardiac defects.

Recurrence of discordant congenital heart defects in families

BACKGROUND

Variation within a single gene might produce different congenital heart defects (CHDs) within a family, which could explain the previously reported familial aggregation of discordant CHDs. We investigated whether certain groups of discordant CHDs are more common in families than others.

METHODS AND RESULTS

Using Danish national population and health registers, we identified CHDs among all singletons born in Denmark during 1977-2005 and their first-degree relatives. In a cohort of 1 711 641 persons, 16 777 had CHDs, which we classified into 14 phenotypes. We estimated relative risks of discordant CHDs by history of specific CHDs in first-degree relatives. The relative risk of any dissimilar CHD given the specified CHD in first-degree relatives was as follows: heterotaxia, 2.00 (95% CI, 0.96 to 4.17); conotruncal defects, 2.78 (95% CI, 2.12 to 3.66); atrioventricular septal defects, 2.25 (95% CI, 1.39 to 3.66); anomalous pulmonary venous return, 1.76 (95% CI, 0.66 to 4.64); left- and right-ventricular outflow tract obstruction, 2.55 (95% CI, 1.87 to 3.48) and 3.09 (95% CI, 2.03 to 4.71), respectively; isolated atrial septal defects, 2.76 (95% CI, 2.11 to 3.61); isolated ventricular septal defects, 2.27 (95% CI, 1.75 to 2.94); persistent ductus arteriosus, 1.92 (95% CI, 1.32 to 2.79); other specified CHDs, 3.29 (95% CI, 2.51 to 4.32); and unspecified CHDs, 2.30 (95% CI, 1.76 to 3.00). Relative risks for all pairwise combinations of discordant CHD phenotypes gave no indications that certain constellations of CHDs cluster more in families than others.

CONCLUSIONS

We documented strong familial aggregation of discordant CHD phenotypes. However, we observed no excess clustering of specific CHD phenotypes among the first-degree relatives.

Variants of folate metabolism genes and the risk of conotruncal cardiac defects

BACKGROUND

Although congenital heart defects (CHD) are the most common and serious group of birth defects, relatively little is known about the causes of these conditions and there are no established prevention strategies. There is evidence suggesting that the risk of CHD in general, and conotruncal and ventricular septal defects in particular, may be related to maternal folate status as well as genetic variants in folate-related genes. However, efforts to establish the relationships between these factors and CHD risk have been hampered by a number of factors including small study sample sizes and phenotypic heterogeneity.

METHODS AND RESULTS

The present study examined the relationships between variation in 9 folate-related genes and a subset of CHD phenotypes (ie, conotruncal defects, perimembranous and malalignment type ventricular septal defects, and isolated aortic arch anomalies) in a cohort of >700 case-parent triads. Further, both maternal and embryonic genetic effects were considered. Analyses of the study data confirmed an earlier reported association between embryonic genotype for MTHFR A1298C and disease risk (unadjusted P=0.002).

CONCLUSIONS

These results represent the most comprehensive and powerful analysis of the relationship between CHD and folate-related genes reported to date, and provide additional evidence that, similar to neural tube defects, this subset of CHD is folate related.

Cryptic chromosomal abnormalities identified in children with congenital heart disease

Congenital heart disease (CHD) is the most common type of birth defect, and the etiology of most cases is unknown. CHD often occurs in association with other birth malformations, and only in a minority are disease-causing chromosomal abnormalities identified. We hypothesized that children with CHD and additional birth malformations have cryptic chromosomal abnormalities that might be uncovered using recently developed DNA microarray-based methodologies. We recruited 20 children with diverse forms of CHD and additional birth defects who had no chromosomal abnormality identified by conventional cytogenetic testing. Using whole-genome array comparative genomic hybridization, we screened this population, along with a matched control population with isolated heart defects, for chromosomal copy number variations. We discovered disease-causing cryptic chromosomal abnormalities in five children with CHD and additional birth defects versus none with isolated CHD. The chromosomal abnormalities included three unbalanced translocations, one interstitial duplication, and one interstitial deletion. The genetic abnormalities were predominantly identified in children with CHD and a neurologic abnormality. Our results suggest that a significant percentage of children with CHD and neurologic abnormalities harbor subtle chromosomal abnormalities. We propose that children who meet these two criteria should receive more extensive genetic testing to detect potential cryptic chromosomal abnormalities.

Influence of consanguinity on the pattern of familial aggregation of congenital cardiovascular anomalies in an outpatient population: studies from the eastern province of Saudi Arabia

BACKGROUND

Familial aggregation of congenital heart disease (CHD) has been well described in different populations, in particular those with a high consanguinity rate. Extensive genetic study of affected families has improved the understanding of basic genetics of different cardiac lesions.

OBJECTIVE

To identify the role of consanguinity as a risk factor among familial cases of CHD in a stable outpatient population of a tertiary care center in the Eastern Province of Saudi Arabia.

METHODS

All familial cases of CHD seen over 5 years (1996-2000) in the Division of Pediatric Cardiology were identified. The presence or absence of parental consanguinity (first cousin marriage) was defined in each of these families.

RESULTS

Ninety-three cases were identified in 37 families. Twenty-three (62%) families resulted from consanguineous marriages. In 4 families where there were 2 marriages, the affected children came from the consanguineous marriage in 3 of these families. Discordant lesions occur only among non-consanguineous cases, while all consanguineous cases were concordant. Five sets of twins of the same sex (one set are monozygotic by DNA analysis) occurred among consanguineous marriages, in 3 of these both twins were affected with the same disease. Affected parents were seen in 2 families with consanguineous marriage and none in the non-consanguineous marriages. The prevalence of dilated cardiomyopathy was much higher among consanguineous cases (26 vs. 2).

CONCLUSIONS

Familial aggregation of congenital heart disease is common in our population. Consanguinity is common in these families, and the distribution of congenital heart disease differs in this subgroup compared to the rest of the familial cases. Further genetic studies of these families may help to shed more light on basic genetics and the specific pathogenetic mechanisms involved.

Management of low birth weight infants with congenital heart disease

Low birth weight infants with congenital heart disease (CHD) have a higher mortality risk and likely a higher morbidity risk than their preterm or appropriate for gestational age counterparts without CHD and term counterparts with CHD. As our understanding of the pathophysiology and treatment of the diseases associated with prematurity and growth restriction improves, the outcomes for these infants should continue to improve. In addition, as more of these infants survive and are referred for surgery, operative techniques and strategies are likely to continue to improve. At this time, there is no adequate evidence that mortality is improved by delaying surgery for weight gain or performing palliative operations initially. Given the challenging physiology in this population, optimal management includes early referral to a tertiary or quaternary facility and a multidisciplinary team approach consisting of cardiologists, neonatologists, surgeons, nurses, perfusionists, and anesthesiologists.

Congenital heart disease in a population of dizygotic twins: an echocardiographic study

BACKGROUND

Congenital heart disease (CHD) is the most common malformation in the fetal and neonatal period but little is known about its cause. The distribution analysis of CHD in dizygotic twins could provide a useful tool to evaluate the role of genetic and environmental factors in the development of CHD. Dizygotic twins are siblings with different genes, growing together in the same womb.

AIM OF STUDY

To investigate the occurrence of CHD in a large sample of dizygotic twins of nonconsanguineous healthy parents, comparing the data from non-twin patients.

METHODS

From January 1999 to December 2002, we enrolled 1743 CHD patients with, at least 1 sibling, and 66 pairs of dizygotic twins, referred to our tertiary center. The diagnosis of CHD was based on clinical and echocardiographic evaluation.

RESULTS

Considering only the sibling nearest in age for each non-twin patient the recurrence was 67/1743 (3.8%). Among these 67 patients, 35 (52.2%) had a sibling with the same or similar CHD. Conversely, considering all 1886 siblings, recurrence of CHD in the non-twin group was 70/1743 (4%). Of the 70 patients, 36 (36/70, 51.4%) had a sibling with the same suspected pathogenic mechanism of CHD. In 9/66 pairs of twins (13.6%), both siblings had a CHD. In the nine pairs of twins in whom both siblings had a CHD, the percentage of concordance (based on the suspected pathogenic mechanism) for CHD was 100% (p<0.05).

CONCLUSIONS

Our findings suggest that the higher recurrence and concordance of CHD found in dizygotic twins could depend on some poorly identified environmental risk during the pregnancy.

Familial recurrence of nonsyndromic congenital heart defects in first degree relatives of patients with deletion 22q11.2

The majority of nonsyndromic congenital heart defects (CHDs) are considered to follow a multifactorial model of inheritance. Multiple family members affected by CHD can occasionally be detected, and the involvement of several genetic loci interacting with environmental factors is suspected to be implicated. The DiGeorge/velo-cardio-facial syndrome related to microdeletion 22q11.2 (del22) is a genetic condition associated with CHD in most of the cases. We report here on five pedigrees of patients with del22, showing occurrence of nonsyndromic CHD in a first-degree relative of the proband case. Familial aggregation of syndromic and nonsyndromic CHD as observed in our series is to be considered as an unusual pattern of recurrence. The interaction between several different genes and environmental factors, a familial susceptibility predisposing to a specific cardiac malformation, or chance association can all be hypothesized searching an explanation for these particular observations.

Familial recurrence of congenital heart disease in patients with ostium secundum atrial septal defect

AIMS

Ostium secundum atrial septal defect (osASD) is one of the most common cardiac malformations. Few data are available on the familial recurrence of congenital heart disease (CHD), in particular, in a large group of patients with isolated osASD. The aim is to investigate the familial recurrence of CHD in up to third-degree relatives from a large sample of consecutively enrolled patients with osASD, taking into account the influence of degree of relatedness (as number of relatives).

METHODS AND RESULTS

From January 1998 to December 2002, we enrolled 583 patients with osASD and 408 healthy subjects, referred to our tertiary centre. We hypothesized that a positive family history required at least one relative with CHD to constitute a risk factor. In this model of analysis, the null hypothesis is a similar familial history between cases and controls. Among 583 patients with osASD, 109 (19%) had at least one relative with CHD. Among the 408 healthy subjects studied, only 23 (6%) had a family history of CHD. A familial recurrence of CHD was demonstrated in 72 of 312 (23%) patients with isolated osASD and in 37 of 271 (13.6%) patients with non-isolated osASD. Familial recurrence of isolated osASD was demonstrated in 22 of 312 patients (7%) with an isolated osASD and only in six of 271 patients (2.2%) with non-isolated osASD. The familial recurrence risk of isolated osASD in patients with isolated osASD was higher in sibs, especially in sisters (33.3%).

CONCLUSION

This study underscores the role of genetic factors in the determination of CHD, particularly osASD. Our results could represent the basis for further studies to calculate a 'value of family history' to adapt the familial recurrence to the real size of each family group. In this way, we could select families with a 'tendency' to develop CHD, particularly osASD. In these families, we could analyse the genetic pattern to establish abnormalities and the bases of CHD.

A family-based association study of congenital left-sided heart malformations and 5,10 methylenetetrahydrofolate reductase

BACKGROUND

Aortic valve stenosis (AVS), coarctation of the aorta (CoA), and hypoplastic left heart syndrome (HLHS) are obstructive malformations of the left ventricular outflow tract that account for a significant proportion of infant mortality. Two previous small case-control studies suggested methylenetetrahydrofolate reductase (MTHFR) polymorphisms may be associated with this group of malformations.

METHODS

We used a family-based association design with inclusion criteria of nonsyndromic diagnosis of AVS, CoA, and HLHS, powered to detect an odds ratio for the heterozygote of <1.5. A total of 207 affected offspring-parent trios were genotyped by restriction fragment length polymorphisms at the two common polymorphic loci C677T and A1298C.

RESULTS

Error rate estimation based on replicate samples was 0.76%. Mendelian inconsistency at either polymorphism was noted in 10 trios, for a calculated undetected error rate of 1.95%. A total of 197 trios were analyzed using the transmission disequilibrium test. Significant association was not found between both the C677T or A1298C polymorphisms and presence of a heart defect, whether analyzed as a group, or by sex, ethnicity, or specific diagnosis. A log-linear analysis did not find increased relative risk based on the maternal genotype.

CONCLUSIONS

We were unable to replicate previous association studies and concluded that neither the affected nor the maternal MTHFR genotype, by itself, is a major risk factor for congenital left ventricular outflow tract malformations.

Counselling following a diagnosis of congenital heart disease

Counselling the parents following a diagnosis of fetal congenital heart disease (CHD) is as important a task for the fetal cardiologist, as the skill involved in achieving an accurate diagnosis. The counsellor will base prognosis not only on the diagnosis itself but also on the security of diagnosis, the stage in gestation and potential for change, the association with extracardiac malformations and the known results of treatment. Depending on the gestational age and legal situation the counsellor is operating in, termination of pregnancy may be one of the options to consider and one that should always be raised in discussion. Thus, the parents may be in the position of making a crucial decision concerning the management of the pregnancy on the basis of the information received, so it is vital that the counsellor is truly able to communicate with them, whatever be their level of understanding.

Temporal variability in birth prevalence of congenital heart defects as recorded by a general birth defects registry

OBJECTIVE

Our aim was to examine the temporal variability in congenital heart defect (CHD) birth prevalence from 1980 to 2000 in Emilia-Romagna, Italy.

METHODS

The study population consisted of all infants, surveyed by the Emilia-Romagna birth defects registry (Indagine Malformazioni conpenite in Emilia-Romagna [IMER]), who were affected by CHDs. A simplified classification into "simple" and "complex " CHD was adopted. A comparison with another epidemiologic study using different methodology in the same area was performed.

RESULTS

From 1980 to 2000, IMER ascertained 2442 live births with CHD of 480,793 infants born, with an average CHD birth prevalence of 5.1% (Range, 3.1% to 7.5%). A significant increase in prevalence of simple CHD during the second decade of the study was demonstrated because of an increased recognition of "minor" cardiac lesions among the simple CHD. The birth prevalence of complex CHD remained stable.

CONCLUSIONS

The apparent increase in live births with CHD results mainly from the current widespread availability of color Doppler echocardiography, which allows the early detection of the "minor" cardiac defects. Other differences are the result of the sources of ascertainment, diagnostic criteria, system of classification, and especially the age limit for enrolling infants with suspected CHD.

Complete transposition of the great arteries: patterns of congenital heart disease in familial precurrence

BACKGROUND

Transposition of the great arteries (TGA) is considered to be associated only rarely with genetic syndromes and to have a low risk of precurrence among relatives of affected patients. Because most family studies have involved a relatively small number of patients and evaluated all types of TGA as a single group, we performed a large, prospective study investigating the precurrence of congenital heart disease in families of children with complete, nonsyndromic TGA.

METHODS AND RESULTS

From January 1997 through December 2000, 370 patients with nonsyndromic, complete TGA were consecutively evaluated and enrolled in the study. The occurrence of cardiac and noncardiac anomalies among relatives of the probands was investigated. Relatives with congenital heart disease were found in 37 of 370 families (10%), including 5 of 37 families (13.5%) with more than one affected relative. TGA itself was the most common precurrent malformation: complete TGA occurred in 6 families and congenitally corrected TGA occurred in 5 families. Precurrence risks for congenital heart disease were calculated at 1.8% (8 of 436) for siblings, 0.5% (4 of 740) for parents, 0.5% (16 of 3261) for first cousins, 0.2% (4 of 2101) for uncles/aunts, and 0.06% (1 of 1480) for grandparents.

CONCLUSIONS

The present study shows that TGA is not always sporadic in families. Precurrence of concordant cardiac defects within affected family members supports monogenic or oligogenic inheritance of TGA in certain kindreds. Moreover, the occurrence of complete TGA and congenitally corrected TGA among first-degree relatives in several different families strongly suggests an underlying pathogenetic link between these 2 malformations that has been previously unrecognized.

Maternal issues affecting the fetus

Maternal disorders and exposures that affect fetal cardiac structure and function are reviewed, emphasizing fetal echocardiographic diagnosis and monitoring, and approaches for in utero therapy. Maternal diabetes, hyperthyroidism, lupus erythematosis, epilepsy, congenital heart disease, infections, and drug exposures are considered.

Diagnosis and management of the newborn with suspected congenital heart disease

In critical congenital heart lesions, the ultimate outcome depends on timely and accurate diagnosis of the structural anomaly, the evaluation and resuscitation of secondary organ damage, effective lesion-specific preoperative management, and the appropriate timing and type of surgery. Crucial to this process is continuous communication among medical, surgical, and nursing disciplines.

Atrioventricular septal defects: possible etiologic differences between complete and partial defects

BACKGROUND

Recent advances in clinical, pathological, and genetic aspects of atrioventricular septal defects (AVSD) have set the stage for epidemiologic investigations into possible risk factors. Previous analyses of the total case group of AVSD included complete and partial subtypes without analysis of the subsets.

METHODS

To address the question of possible morphogenetic heterogeneity of AVSD, the Baltimore-Washington Infant Study data on live-born cases and controls (1981-1989) was reanalyzed for potential environmental and genetic risk-factor associations in complete AVSD (n = 213), with separate comparisons to the atrial (n = 75) and the ventricular (n = 32) forms of partial AVSD.

RESULTS

Complete and ventricular forms of AVSD had a similar proportion of isolated cases (12.2% and 15.6%, respectively, without associated extracardiac anomalies) and high rates of Down syndrome, whereas the atrial form of partial AVSD included 55% isolated cases. Trisomy 18 occurred in 22% of infants with the ventricular form, compared with <2% in the other AVSD groups. Analysis of potential risk factors revealed further distinctions. Complete AVSD as an isolated cardiac defect was strongly associated with maternal diabetes (odds ratio [OR] = 20.6; 95% confidence interval [CI] =5.6-76.4) and also with antitussive use (OR = 8.8; CI = 1.2-48.2); there were no strong associations other than maternal age among Down syndrome infants with this type of heart defect. Isolated cases with the atrial type of partial AVSD were associated with a family history of heart defects (OR = 6.2; CI = 1.4-24.4) and with paternal occupational exposures to ionizing radiation (OR = 5.1; CI = 1.4-27.4), but no risk factors were associated with Down syndrome. There were no significant associations of any risk factors in the numerically small subsets of isolated and Down syndrome cases with the ventricular form of partial AVSD.

CONCLUSIONS

These results indicate a similar risk profile of complete AVSD and the ventricular type of partial AVSD, with a possible subset of the latter due to trisomy 18. Maternal diabetes constituted a potentially preventable risk factor for the most severe, complete form of AVSD.

The Italian Multicentric Study on Epidemiology of Congenital Heart Disease: first step of the analysis. Working Party of the Italian Society of Pediatric Cardiology

We present the aims, methodology and initial results from the Italian Multicentric Study for the registration and follow-up of congenital heart disease. The general aims are to measure the prevalence of congenital heart disease in different geographic areas of Italy, and to assess the survival and outcome of affected babies. During the years 1992 and 1993, eighteen centers for Pediatric Cardiology spread all over the Country enrolled 1445 new babies with congenital cardiac malformations from a population of 341,647 surveyed livebirths. The new cases were registered using the same methodologic criteria of the EUROCAT study in order to evaluate differences and/or similarities between the studies. The prevalence varied between 1.8% and 8.1%; the average being 4.6%. The large range in prevalence is presumed to be related to different customs and hierarchies in flow and referral of patients. We provide total prevalence of individual lesions, and distribution of sentinel cardiac anomalies, in the Italian study and compare them with EUROCAT. Isolated ventricular septal defect is the most common lesion (39%); followed by atrial septal defect (7.5%); pulmonary valvar stenosis (7.3%); atrioventricular septal defects (5.4%); patency of the arterial duct (3.8%); complete transposition (3.7%); tetralogy of Fallot (3.3%); aortic coarctation (2.4%); aortic valvar stenosis (2.2%); and left heart hypoplasia (1.8%). The echographic stratification of ventricular and atrial septal defects, by location and size, was in keeping with the findings of the EUROCAT study. Because of the recent widespread availability of color-Doppler techniques, the stratification of aortic and pulmonary valvar stenosis was an innovative approach in our study. Among the complex cardiovascular anomalies, double inlet ventricle and pulmonary atresia had a proportion of about 2% each; with double outlet right ventricle, common arterial trunk, Ebstein's malformation, tricuspid atresia, interrupted aortic arch and totally anomalous pulmonary venous connection having a proportion ranging from 0.5 to 0.8%. We discuss clinical features, such as frequency of extracardiac anomalies and familial aggregation of congenital heart disease, in comparison with the EUROCAT data.

Congenital heart defect in sibs with discordant karyotypes

Congenital heart defects (CHDs) are genetically heterogeneous, associated with a variety of genetic conditions. Familial aggregation of CHD in patients with and without Down syndrome is rare. We report on the occurrence of concordant CHD in three sets of sibs with discordant karyotypes. In the first family, atrioventricular canal (AVC) was diagnosed in a chromosomally normal child and in his brother with Down syndrome. In the second family, AVC was associated with trisomy 21 in one sib and with trisomy 18 in the other. In the third family, tetralogy of Fallot was present in one patient with Down syndrome and in his nonsyndromic sister. Although the genetic heterogeneity of Down and non-Down CHD is not disputed, a susceptibility to both euploid and aneuploid CHDs could exist, and common predisposing factors could play a role in both conditions.

Prospective diagnosis of 1,006 consecutive cases of congenital heart disease in the fetus

OBJECTIVE

This report describes our experience with fetal congenital heart disease since 1980.

BACKGROUND

Knowledge and expertise in the diagnosis, management and natural history of fetal congenital heart disease is increasingly demanded by both obstetricians and parents. The analysis of a large series should help the pediatric cardiologist to provide this service.

METHODS

The notes of 1,006 patients, where a prospective diagnosis of fetal congenital heart disease was made, were reviewed. The reason for referral, the diagnosis made, the accuracy of diagnosis, the fetal karyotype and the outcome of the pregnancy were noted. The cases were grouped into malformation categories, and the spectrum of disease seen was compared with that found in infants.

RESULTS

Most fetal cardiac anomalies are now suspected by the ultrasonographer during obstetric scanning. A different incidence of abnormalities is seen compared with that expected in infants. Chromosomal anomalies were more frequent in the fetus than in live births. The accuracy of diagnosis was good. The survival rate after diagnosis was poor because of frequent parental choice to interrupt pregnancy and the complexity of disease.

CONCLUSIONS

A large experience with fetal congenital heart disease allows the spectrum of disease to be described with accuracy and compared with that in infancy. Knowledge of the natural history of heart malformations when they present in the fetus allows accurate counseling to be offered to the parents. If the trend in parental decisions found in this series continues, a smaller number of infants and children with complex cardiac lesions will present in postnatal life.

A second-generation study of 427 probands with congenital heart defects and their 837 children

OBJECTIVES

This study attempted to answer the question, Do mothers with congenital cardiovascular defects have more affected children than fathers with cardiac anomalies?

BACKGROUND

In the 1950s to 1960s, concern was expressed about the safety of pregnancy in women with cardiac anomalies and the possibility of inheritance.

METHODS

In a prospective study over 25 years, 236 women with cardiac defects were followed through pregnancy, and their 418 offspring were examined during their 1st 3 years. A high incidence of congenital cardiac malformations was noted. Then, a retrospective study of 191 men from the same clinic group and their total family (419 children) was performed to compare the incidence of affected children between the maternal study and this subsequent paternal study.

RESULTS

Of 837 live children of these 427 probands, 14.1% (118) had a congenital heart defect (13.4% in the maternal study, 14.8% in the paternal study). There was no correlation with the surgical status of the proband. Concordance was somewhat greater among the children of affected mothers compared with those of affected fathers. Included in these studies were 31 high risk probands, 10 with genetic syndromes and 21 who had an affected sibling. Respectively, 53% and 41% of their children had cardiac anomalies, with a concordance > 50%; three fourths of these children had moderate to severe anomalies.

CONCLUSIONS

The incidence of congenital heart defects in the children was not statistically different between the maternal and paternal studies. With removal of the high risk probands from the total study group, the risk of one affected parent having a child with a cardiac anomaly was 10.7%. Of the entire 837 children, only 7.5% had moderate or severe defects.

Cardiomyopathy in infancy: observations in an epidemiologic study

Cardiomyopathy (Cm), a rare form of cardiac disease in infancy, is receiving increasing attention stimulated by the availability of endocardial biopsy and new forms of therapy. Population-based information on frequency of occurrence, types, and maternal and infant characteristics of this diverse group of heart muscle disorders has been obtained in the course of an etiologic study on cardiovascular disease in infancy. The Baltimore-Washington Infant Study (BWIS) enrolled 2659 infants with heart disease and 2801 control infants between January 1, 1981 and March 31, 1987, a 6-year prevalence of 4.46/1000 live births. Fifty-six infants had cardiomyopathy, in the absence of a structural defect (prevalence 1/10,000). The cases were classified clinicopathologically as follows: dilated Cm (n = 17), hypertrophic Cm (n = 26), tumor (n = 5), endocardial fibroelastosis (n = 5), glycogen storage (n = 1), mucocutaneous lymph node syndrome (n = 1), and infarction (n = 1). Eleven syndromic associations and six metabolic disturbances indicate genetic risk factors. Some of the same syndromes occurred in other infants who had structural cardiac abnormalities. This overlap suggests that embryonic myocardial disease might sometimes be responsible for altered cardiac structures, possibly secondary to hemodynamic changes. Familial myocardial disease occurred in two infants with hypertrophic Cm. The Cm group did not differ by race and sex from controls, but the mothers were of lower educational and occupational status with less private care and with later registration for pregnancy care. The descriptive epidemiology of this population-based case group provides evidence of greater etiologic heterogeneity than has been shown in clinical reports.

Spectrum of heart malformations in mice with situs solitus, situs inversus, and associated visceral heterotaxy

BACKGROUND

We present a study of the heart malformations found in a collection of mouse fetuses of the iv/iv strain between days 16.5 and 18.5 of gestation.

METHODS AND RESULTS

One hundred hearts were serially sectioned and studied by segmental analysis with a light microscope. Forty additional hearts were analyzed with a scanning microscope. Forty percent of the hearts were found to be malformed. The most frequently occurring heart malformations were persistence of the sinus venosus (9%), common atrium (17%), common atrioventricular canal (24%), double-outlet right ventricle (12%), Fallot's tetralogy (8%), and transposition of the great arteries (5%). These malformations do not usually occur in isolation but rather appear in the formation of complex cardiopathies. The most severe and frequent is the combination of persistence of sinus venosus, common atrium, common atrioventricular canal, and double-outlet right ventricle; this is the "bulboventricular heart." The morphology of each lesion, as well as the degree of association, is similar to that found in human hearts with complex cardiopathies. Some of these cardiopathies appear to be directly related to formation of the cardiac loop. The iv/iv mouse appears to constitute an excellent model with which to study the etiology and pathogenesis of complex heart defects in humans. These hearts show a high phenotypic variability in the presentation of heart lesions. From a genetic viewpoint, there is a basic defect--the bulboventricular heart--which can be considered congenital. The other malformations can be considered formes frustes of the defect type.

CONCLUSIONS

The iv gene is a developmental gene that affects basic developmental mechanisms. In this regard, heart lesions may not be the primary result of the abnormal gene activity but rather are secondary to defective interactions during cardiac development.

The inheritance of conotruncal malformations: a review and report of two siblings with tetralogy of Fallot with pulmonary atresia

Congenital heart defects (CHD) are a group of structural abnormalities that in humans have a combined incidence of approximately 1%. It is estimated that 4-5% of CHD are associated with chromosome abnormalities, 1-2% are associated with single gene syndromes, 1-2% are due to known teratogens, with the rest presumably determined multifactorially. We report on a brother and sister with tetralogy of Fallot with pulmonary atresia, and review the inheritance of familial conotruncal anomalies. We feel the small number of family clusters and the rare instances of consanguinity in non-syndromal conotruncal defects are consistent with multifactorial determination. While it is prudent in counseling families with 2 or more individuals with conotruncal CHD to raise the possibility of single gene inheritance, we believe that current empiric recurrence risk estimates most accurately reflect their risks.

Are offspring of women with hereditary hematologic disorders at increased risk of congenital cardiovascular malformations?

Hereditary hematologic disorders (HHD) have been reported in excess among infants and families of infants with congenital cardiovascular malformations (CCM) compared with controls, suggesting possible common pathogenetic mechanisms. It is plausible that hemodynamic changes during pregnancy associated with HHD could affect cardiac morphogenesis. To investigate whether offspring of women with selected HHD have an excess risk of CCM, the authors examined data from a nationwide birth defects monitoring program (BDMP) covering about 2.9 million births in the United States between 1982 and 1988. The system ascertains major birth defects diagnosed in the newborn period. An anonymous linkage procedure linked maternal obstetric records with newborn records using demographic, diagnostic, and geographic variables. A total of 1,239 mothers were identified with selected HHD (47 hereditary spherocytosis, 575 thalassemias, 310 sickle cell anemia, 88 other hereditary hemolytic anemias, 159 von Willebrand disease, and 60 other congenital coagulopathies). In all, 14 infants received a newborn discharge diagnosis of CCM (expected number based on population rates of CCM from the same hospitals and time period is 7.74; P = 0.0268). No single CCM entity accounted for this excess. In contrast, 8 infants had major non-CCM defects (expected number 7.46; P = 0.466). These data suggest an excess risk of CCM among offspring of women with selected HHD. Further studies are needed to explore these findings and to evaluate the pathogenetic significance of this association.