Clonal Hematopoiesis of Indeterminate Potential With Loss of Tet2 Enhances Risk for Atrial Fibrillation Through Nlrp3 Inflammasome Activation

BACKGROUND

Clonal hematopoiesis of indeterminate potential (CHIP), a common age-associated phenomenon, associates with increased risk of both hematological malignancy and cardiovascular disease. Although CHIP is known to increase the risk of myocardial infarction and heart failure, the influence of CHIP in cardiac arrhythmias, such as atrial fibrillation (AF), is less explored.

METHODS

CHIP prevalence was determined in the UK Biobank, and incident AF analysis was stratified by CHIP status and clone size using Cox proportional hazard models. Lethally irradiated mice were transplanted with hematopoietic-specific loss of Tet2, hematopoietic-specific loss of Tet2 and Nlrp3, or wild-type control and fed a Western diet, compounded with or without NLRP3 (NLR [NACHT, LRR {leucine rich repeat}] family pyrin domain containing protein 3) inhibitor, NP3-361, for 6 to 9 weeks. Mice underwent in vivo invasive electrophysiology studies and ex vivo optical mapping. Cardiomyocytes from Ldlr-/- mice with hematopoietic-specific loss of Tet2 or wild-type control and fed a Western diet were isolated to evaluate calcium signaling dynamics and analysis. Cocultures of pluripotent stem cell-derived atrial cardiomyocytes were incubated with Tet2-deficient bone marrow-derived macrophages, wild-type control, or cytokines IL-1β (interleukin 1β) or IL-6 (interleukin 6).

RESULTS

Analysis of the UK Biobank showed individuals with CHIP, in particular TET2 CHIP, have increased incident AF. Hematopoietic-specific inactivation of Tet2 increases AF propensity in atherogenic and nonatherogenic mouse models and is associated with increased Nlrp3 expression and CaMKII (Ca2+/calmodulin-dependent protein kinase II) activation, with AF susceptibility prevented by inactivation of Nlrp3. Cardiomyocytes isolated from Ldlr-/- mice with hematopoietic inactivation of Tet2 and fed a Western diet have impaired calcium release from the sarcoplasmic reticulum into the cytosol, contributing to atrial arrhythmogenesis. Abnormal sarcoplasmic reticulum calcium release was recapitulated in cocultures of cardiomyocytes with the addition of Tet2-deficient macrophages or cytokines IL-1β or IL-6.

CONCLUSIONS

We identified a modest association between CHIP, particularly TET2 CHIP, and incident AF in the UK Biobank population. In a mouse model of AF resulting from hematopoietic-specific inactivation of Tet2, we propose altered calcium handling as an arrhythmogenic mechanism, dependent on Nlrp3 inflammasome activation. Our data are in keeping with previous studies of CHIP in cardiovascular disease, and further studies into the therapeutic potential of NLRP3 inhibition for individuals with TET2 CHIP may be warranted.

A new opening on aortic stenosis: predicting prognosis with clonal haematopoiesis

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Sixteenth-century German woodcut of a male infant with possible disorganization

History has preserved a beautiful 16th century woodcut print, which depicts an infant with several malformations. The German inscription describes the infant's hypotonia and ectopic growths, and the image itself shows a child with an ectopic accessory third lower limb, a large papilla, and an omphalocele-like growth. The 'case' bears striking similarity to reported human cases of the disorganization (Ds) syndrome. This article describes the woodcut, describes Ds, and then explains how the image may represent the earliest depiction of Ds in history.

The role of E3 ligases in autoimmunity and the regulation of autoreactive T cells

The ubiquitination of proteins by E3 ligases has become an important regulatory mechanism for a variety of immune functions, including the maintenance of self tolerance and suppression of autoreactive T cell development. This review highlights recent advances in our knowledge of the functions in this context of known and potential E3 ligases, including autoimmune regulator (AIRE), TNF receptor-associated factor 6 (TRAF6), Casitas B cell lymphoma b (Cbl-b), gene related to anergy in lymphocytes (GRAIL), Itch, and Roquin. We discuss how disruptions to these molecules may contribute to the loss of T cell homeostasis and the pathogenesis of autoimmunity. We also report on the implications of the potential coordinated actions of these molecules for T cell anergy and regulatory T cell (Treg) functions. The great diversity of E3 ligases and the growing list of cellular processes in which ubiquitination plays a role make for an exciting field of research. Findings emerging from these investigations may suggest ways to exploit the therapeutic potential of manipulating ubiquitination, particularly for autoimmune disorders.

Exclusion of growth factor gene mutations as a common cause of Sotos syndrome

Sotos syndrome is characterized by somatic overgrowth, i.e., macrocephaly and tall stature. Because the cause and pathogenesis of Sotos syndrome remain unknown, we selected nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF) and neurotrophin 3 (NT-3) as possible genes mutated in Sotos syndrome. In seven patients with the classic phenotype, we excluded mutations in these growth factor genes. It is possible that these three genes are not involved in the cause of Sotos syndrome, or alternatively, mutations could not be identified in the small number of patients studied.

Cardiovascular malformations and other cardiovascular abnormalities in neurofibromatosis 1

Although it is well recognized that a peripheral vasculopathy may occur in patients with neurofibromatosis 1 (NF1), it is unclear whether cardiovascular abnormalities are more common. We reviewed the frequency of cardiovascular abnormalities, in particular, cardiovascular malformations (CVMs), among 2322 patients with definite NF1 in the National Neurofibromatosis Foundation International Database from 1991-98. Cardiovascular malformations were reported in 54/2322 (2.3%) of the NF1 patients, only 4 of whom had Watson syndrome or NF1-Noonan syndrome. There was a predominance of Class II "flow" defects [Clark, 1995: Moss and Adams' Heart Disease in Infants, Children, and Adolescents Including the Fetus and Young Adult. p 60-70] (43/54, 80%) among the NF1 patients with CVMs. Pulmonic stenosis, that was present in 25 NF1 patients, and aortic coarctation, that occurred in 5, constitute much larger proportions of all CVMs than expected. Of interest was the paucity of Class I conotruncal defects (2 patients with tetralogy of Fallot), and the absence of atrioventricular canal, anomalous pulmonary venous return, complex single ventricle and laterality defects. Besides the 54 patients with CVMs, there were 27 patients with other cardiac abnormalities (16 with murmur, 5 with mitral valve prolapse, 1 with intracardiac tumor, and 5 with electrocardiogram abnormalities). No patient in this study had hypertrophic cardiomyopathy. There were 16 patients who had a peripheral vascular abnormality without an intracardiac CVM, plus an additional 4 patients among those with a CVM who also had a peripheral vascular abnormality.

Heterotaxy: associated conditions and hospital-based prevalence in newborns

PURPOSE

To provide insight into the possible etiology and prevalence of heterotaxy, we studied conditions associated with heterotaxy in a consecutive hospital population of newborns.

METHODS

From 1972 to March, 1999 (except February 16, 1972 to December 31, 1978), 58 cases of heterotaxy were ascertained from a cohort of 201,084 births in the ongoing Active Malformation Surveillance Program at the Brigham and Women's Hospital. This registry includes livebirths, stillbirths, and elective abortions. Prevalence among nontransfers (i.e., patients whose mothers had planned delivery at this hospital) was calculated as approximately 1 per 10,000 total births (20 of 201,084).

RESULTS

We analyzed a total of 58 patients consisting of 20 (34%) nontransfers and 38 (66%) transfers. Patients were categorized by spleen status as having asplenia (7 nontransfers, 25 total), polysplenia (8, 20), right spleen (4, 11), normal left (0, 1), and unknown (1, 0). Among the 20 nontransfer and 59 total heterotaxy patients, the following associated medical conditions were present: chromosome abnormality (1 nontransfer, 2 total), suspected Mendelian or chromosome microdeletion disorder (1 nontransfer, 6 total), and maternal insulin-dependent diabetes mellitus (1 nontransfer, 2 total). There were 6 twins (1 member each from 6 twin pairs including 1 dizygous, 4 monozygous, 1 conjoined; 2 were nontransfers). An associated condition occurred in 5 (25%) nontransfer and 16 (28%) total patients, or among 10 of 53 singleton births (19%).

CONCLUSIONS

Although most cases of heterotaxy in this series were sporadic events, an associated condition was present in about one-fourth of the cases. Not all of these conditions would be considered causative etiologies. Based on this small series alone, maternal insulin-dependent diabetes cannot be viewed as a risk factor for heterotaxy. However, the specific association of diabetes with polysplenia with/without left atrial isomerism is noteworthy, and adds weight to animal and epidemiologic case-control data.

Exclusion of the branchio-oto-renal syndrome locus (EYA1) from patients with branchio-oculo-facial syndrome

In addition to craniofacial, auricular, ophthalmologic, and oral anomalies, the distinctive phenotype of the branchio-oculo-facial (BOF) syndrome (MIM 113620) includes skin defects in the neck or infra/supra-auricular region. These unusual areas of thin, erythematous wrinkled skin differ from the discrete cervical pits, cysts, and fistulas of the branchio-oto-renal (BOR) syndrome (MIM 113650). Although the BOF and BOR syndromes are sufficiently distinctive that they should not be confused, both can be associated with nasolacrimal duct stenosis, deafness, prehelical pits, malformed pinna, and renal anomalies. Furthermore, a reported father and son [Legius et al., 1990, Clin Genet 37:347-500] had features of both conditions. It was not clear whether they had an atypical presentation of either BOR or BOF syndrome, or represented a private syndrome. In light of these issues, we selected the BOR locus (EYA1) as a possible gene mutation for the BOF syndrome. In five BOF patients, there were no mutations detected in the EYA1 gene, suggesting that it is not allelic to the BOR syndrome.

Genetic aspects of atrioventricular septal defects

Formation of the atrioventricular canal (AVC) results from complex interactions of components of the extracellular matrix. In response to signaling molecules, endothelial/mesenchymal transformations are crucial to normal development of the AVC. Atrioventricular septal defects (AVSDs) can result from arrest or interruption of normal endocardial cushion development. The presence of AVSDs has been associated with chromosome abnormalities, laterality or left-right axis abnormalities, and a variety of syndromes. An AVSD susceptibility gene has been identified in a large kindred with many affected members. Studies of transcription factors and signaling molecules in heart development over the past decade are paving the way for our understanding of the heterogeneous mechanisms of causation of AVSDs.

Circumferential abdominal skin defect possibly due to umbilical cord encirclement

We report on a newborn black male twin with a distinctive circumferential abdominal skin defect who was identified through the Active Malformation Surveillance Program at the Brigham and Women's Hospital. There were no other malformations, and amniotic disruption was not present. Although it cannot be proven, we believe that this skin defect may have been caused by in utero encirclement of the abdomen by an umbilical cord.

Cardiovascular malformations: changes in prevalence and birth status, 1972-1990

Through an ongoing hospital-based active malformation surveillance program, we identified cardiovascular malformations (CVMs) in 3.3 per 1,000 liveborn and stillborn infants, and fetuses from pregnancies terminated electively during a 15-year period. We excluded the children of mothers who had planned delivery elsewhere, but were transferred for care of anomalies that had been detected in prenatal screening. Birth status changed markedly during the study with a significant increase in elective terminations of fetuses with a CVM from 0 to 22% (P < 0.01 based on a test for trend). The proportion of liveborn infants with CVMs decreased from 90% to 73% (P < 0.01); the frequency of stillbirths did not change. During the study period, there was a significant increase in the prevalence of CVMs in all births (P < 0.01) and elective terminations (P < 0.01). The increase in liveborn prevalence was not statistically significant (P = 0.08). Stillborn prevalence was unchanged. The number of mothers having prenatal ultrasonography (P < 0.01 for trend) and amniocentesis (P < 0.01 for trend) increased steadily. There were significant increases in the proportion of mothers having any ultrasound examination (P < 0.01 for trend), the number of initial ultrasound examinations occurring in the second trimester (P < 0.01 for trend), and the proportion of mothers having amniocentesis (P < 0.01 for trend). There was a significant increasing trend in the proportion of mothers who were 35 years and older (10% in 1972-1974, 26% in 1988-1990, P < 0.01). This hospital-based active surveillance program suggests that more frequent elective terminations had a significant effect on overall birth prevalence of CVMs. This trend would not have been detected by most other surveillance systems which determine prevalence of common birth defects from birth certificates and other forms of administrative reporting, and exclude elective terminations of pregnancy.

Cardiac anomalies in the Simpson-Golabi-Behmel syndrome

Diverse cardiac abnormalities have been reported in patients with the Simpson-Golabi-Behmel syndrome (SGBS), and it is suspected that they are related to the apparently high incidence of early death. To clarify the incidence and significance of the various cardiac abnormalities, we reviewed 101 SGBS patients (89 from the literature, 12 new). All were male, except for one clearly affected female patient with translocation X;1 [Punnett, 1994: Am J Med Genet 50: 391-393]. Ninety-six of 99 (97%) patients had the classic phenotype of macrosomia and typical "coarse" face. Thirty-six patients (36%) had a cardiac abnormality, of whom 26 (26%) had a cardiovascular malformation (CVM). After excluding 24 patients with insufficient clinical data, these percentages among the 77 informative cases were 47% and 34%, respectively. When grouped according to a mechanistic classification, most cases (20/ 26, or 77%) were class II CVMs (attributed to altered embryonic intracardiac flow). Other cardiac abnormalities included cardiomyopathy (n = 4) and electrocardiogram (ECG) conduction or rhythm abnormalities (n = 12); three of the affected patients (25%) also had a CVM. Among 92 informative cases, there were 29 (32%) deaths, a figure that excludes seven elective terminations. Among the 25 patients younger than 3 years, death was associated with a cardiac abnormality in six (23%). GPC3 mutation analysis using Southern blot testing and polymerase chain reaction amplification was performed for 37 of 101 (37%) patients. A mutation was detected in 26 of the 37 patients tested (70%), 12 of whom (46%) had a cardiac abnormality. We conclude that cardiac abnormalities of any type are common in SGBS (almost one-half of informative cases), with CVMs seen in one-third of cases. The heterogeneous ECG abnormalities in this survey must be viewed with caution, since they may represent a genuine component of the syndrome or reporting bias. Determining the true prevalence and natural history of cardiac abnormalities in SGBS will require a larger number of patients and more consistent prospective cardiac evaluations. There are sufficient data to recommend a baseline echocardiogram and ECG in SGBS patients. Data are insufficient to define a cardiac phenotype/molecular correlation.

Adams-Oliver syndrome associated with cardiovascular malformations

We describe two families with Adams-Oliver syndrome (AOS), an autosomal dominant malformation syndrome (MIM No. 10030), in which cardiovascular malformations (CVMs) have been reported previously. In the first family, twin boys and their mother had the typical digital and scalp defects of AOS with various obstructive CVMs of the left heart (bicuspid aortic valve, Shone's complex). At least three other relatives not examined personally are reported to have related CVMs (aortic valve stenosis, hypoplastic left heart syndrome). In the second family, a girl had typical AOS digital and scalp defects and a bicuspid aortic valve. At least three other relatives are reported to be mildly affected. Tetralogy of Fallot had been previously reported as the most common CVM in AOS [Zapata HH, Sletten LJ, Pierport MEM (1995). J Med Genet 47:80-84.]. However, with the addition of these new patients and two other literature reports, we emphasize that approximately 20% have a CVM, frequently obstructive lesions of the left heart. Cardiology consultation should be offered to most patients with AOS.

Further delineation of aortic dilation, dissection, and rupture in patients with Turner syndrome

OBJECTIVE

Although cardiovascular malformations (CVMs) are well-recognized congenital anomalies in Turner syndrome, aortic dilation and dissection are less common and less familiar. Most of the relevant literature is limited to single cases reports or small series. We sought to increase the information available about the frequency and characteristics of aortic dilation in patients with Turner syndrome.

DESIGN

A 1-page survey of cardiac abnormalities, including aortic dilation, was mailed to approximately 1000 (1040 verified) members of the Turner Syndrome Society as an enclosure in the June 1997 newsletter. We also conducted a literature review.

PARTICIPANTS

A total of 245 patients or families of patient members of the Turner Syndrome Society responded to the survey ( approximately 24% response rate).

RESULTS

A CVM was reported in 120 of 232 (52%) respondents to this questionnaire. Obstructive lesions of the left side of the heart predominated and included bicuspid aortic valve (38%) and coarctation (41%). Aortic dilation was reported in at least 15 of 237 respondents (6.3%; 95% confidence interval: 3.6%-10.3%); 2 of 15 (13%) had dissection. Twelve of 15 (80%) patients had an associated risk factor for aortic dilation such as a CVM or hypertension. The 3 (20%) patients who did not have a CVM or hypertension were all younger than 21 years. In the entire group with aortic dilation, 10 of 15 (67%) patients were younger than 21 years. All patients with aortic dilation had involvement of the ascending aorta, and 2 had additional involvement of the descending aorta distal to a repaired coarctation. An update of the literature revealed 68 patients with aortic dilation, dissection, or rupture. An associated CVM or hypertension was reported in 53 of 59 (90%) informative patients. At least 6 (10%) had no predisposing risk factor (information was inadequate for 9 of 68 patients). The following patterns of aortic involvement were identified: ascending +/- descending aorta with coarctation (14); ascending +/- descending aorta without coarctation (39); descending aorta with coarctation (3); descending thoracic or abdominal aorta without coarctation (4); and unspecified (8). Dissection or rupture was reported in 42/68 (62%). Two reported patients died suddenly from aortic dissection in the third trimester of assisted pregnancy. At least 20 (29%) patients were younger than 21 years. One of the 6 (17%) patients with isolated aortic dilation was in this younger group.

CONCLUSIONS

More information is needed about the frequency and natural history of aortic dilation in Turner syndrome. This work contributes new patient data and increases the literature review. Despite the well-recognized limitations of self-reporting, this survey detected aortic dilation with or without dissection in approximately 6% of patients with Turner syndrome. Although rare, this is a potentially catastrophic occurrence, warranting greater awareness among health professionals. In this study and the literature, the vast majority of patients with aortic dilation have an associated risk factor such as a CVM, typically bicuspid aortic valve or coarctation, or systemic hypertension. These patients represent a higher risk group that should be followed appropriately, usually under the direction of a cardiologist. Patients undergoing assisted pregnancy also should be evaluated closely. It is generally accepted that at the time of diagnosis of Turner syndrome, all patients should have a complete cardiology evaluation including echocardiography. The small number of patients with aortic dilation without a CVM, who would not be under the long-term care of a cardiologist, makes it prudent to screen all patients with Turner syndrome for this potentially lethal abnormality. The specific timing for this screening is controversial. Our recommendations for prospective imaging do not represent a rigid standard of care.

CHARGE association: an update and review for the primary pediatrician

CHARGE association is a nonrandom pattern of congenital anomalies that occurs together more frequently than one would expect on the basis of chance. This common multiple anomaly condition has an estimated prevalence of 1:10,000. The number of children diagnosed with CHARGE association is increasing, owing presumably to greater awareness of this condition and advances in the care of complex, chronically ill children, resulting in improved survival and outcome. This review of CHARGE association presents diagnostic criteria that may define a concise, recognizable syndrome with a single pathogenetic basis. This review also summarizes our current understanding of the management for this complex and chronic multiple congenital anomaly condition and discusses the pathogenetic basis for this condition.

Vitamin K deficiency embryopathy: a phenocopy of the warfarin embryopathy due to a disorder of embryonic vitamin K metabolism

Three unrelated infants presented with radiographic punctate calcifications, nasal hypoplasia, and abnormalities of the spine. Additional anomalies included cupped ears in 2 patients and one each with Dandy-Walker malformation with hydrocephaly, congenital cataracts, and peripheral pulmonary artery stenosis. The mothers of these 3 patients had chronic conditions associated with intestinal malabsorption requiring total parenteral nutrition for varying periods of time. The underlying causes of malabsorption were celiac disease, short bowel syndrome secondary to surgical resection, and jejuno-ileal bypass, respectively. Bleeding diathesis occurred in one mother requiring vitamin K supplementation during the second and third trimesters of pregnancy. We speculate that the chondrodysplasia punctata and other abnormalities in these children were caused by an acquired maternal vitamin K deficiency manifested during early pregnancy. However, the involvement of other vitamin deficiencies cannot be excluded. Thus, vitamin K deficiency of the embryo secondary to maternal malabsorption appears to be a third vitamin K-related mechanism leading to chondrodysplasia punctata in addition to warfarin embryopathy and epoxide reductase deficiency (pseudo-warfarin embryopathy).

Cardiovascular malformations in Smith-Lemli-Opitz syndrome

We reviewed 215 patients (59 new, 156 from the literature) with Smith-Lemli-Opitz syndrome (SLOS), and found that 95 (44%) had a cardiovascular malformation (CVM). Classifying CVMs by disordered embryonic mechanisms, there were 5 (5.3%) class 1 (ectomesenchymal tissue migration abnormalities), 56 (58.9%) class II (abnormal intracardiac blood flow), 25 (26.3%) class IV (abnormal extracellular matrix), and 5 (5.3%) class V (abnormal targeted growth). Comparing the frequencies of individual CVMs in this series with a control group (the Baltimore-Washington Infant Study), there were 6 individual CVMs which showed a significant difference from expected values. When frequencies of CVMs in SLOS were analyzed by mechanistic class, classes IV and V were significantly more frequent, and class I significantly less frequent, than the control group. Although CVMs in SLOS display mechanistic heterogeneity, with an overall predominance of class II CVMs, the developmental error appears to favor alteration of the cardiovascular developmental mechanisms underlying atrioventricular canal and anomalous pulmonary venous return. This information should assist the clinical geneticist evaluating a patient with possible SLOS, and should suggest research direction for the mechanisms responsible for the SLOS phenotype.

Molecular cytogenetic characterisation of the first familial case of partial 9p duplication (p22p24)

We report on a father and daughter with a partial 9p duplication, dup(9)(p22p24). Their phenotype, albeit mild, is characteristic of partial trisomy 9p. Fluorescence in situ hybridisation (FISH) was used to characterise further and confirm the G banding finding. This is the first reported instance of trisomy 9p occurring in two successive generations. The duplicated segment in these two patients is among the smallest segments reported. Comparison of our two patients and 144 reported patients with trisomy 9p (partial or complete trisomy) suggests that the 9p22 region may be responsible for the observed phenotype in 9p duplication cases.

Effect of inhaled salmeterol on sulfur dioxide-induced bronchoconstriction in asthmatic subjects

This study tested the capability of a single 42-microgram dose of inhaled salmeterol xinafoate, a long-acting beta 2-agonist, to protect against bronchoconstrictive effects of exposure to 0.75 ppm sulfur dioxide (SO2) during exercise, for up to 24 h. Ten SO2-responsive adult volunteers with stable asthma were studied under 4 conditions of drug pretreatment/exposure, administered in random order, double-blind: salmeterol/SO2, placebo/SO2, salmeterol/clean air, and placebo/clean air. Each subject underwent 10-min exposure/exercise challenges in a chamber 1, 12, 18, and 24 h after pretreatment. Exercise ventilation rates averaged 29 L/min. Response was measured as the decrement in FEV1 between preexposure and postexposure (lowest value within 30 min). After salmeterol, mean decrement post-SO2 was 7% at 1 h and 12% at 12 h. At 18 and 24 h after salmeterol, and at all times after placebo, mean decrements were 25 to 30%. After 18 and 24 h, salmeterol still improved base-line FEV1 relative to placebo, although improvement was not statistically significant at 24 h. Acute symptom increases accompanied FEV1 decrements.

CONCLUSION

In our asthmatic subjects, pretreatment with salmeterol imparted clinically and statistically significant (p < 0.01) protection against bronchoconstriction induced by SO2/exercise for at least 12 h, and maintained an improvement in lung function for as much as 18 h.

Clinical approach to genetic cardiomyopathy in children

BACKGROUND

Cardiomyopathy (CM) remains one of the leading cardiac causes of death in children, although in the majority of cases, the cause is unknown. To have an impact on morbidity and mortality, attention must shift to etiology-specific treatments. The diagnostic evaluation of children with CM of genetic origin is complicated by the large number of rare genetic causes, the broad range of clinical presentations, and the array of specialized diagnostic tests and biochemical assays.

METHODS AND RESULTS

We present a multidisciplinary diagnostic approach to pediatric CM of genetic etiology. We specify criteria for abnormal left ventricular systolic performance and structure that suggest CM based on established normal echocardiographic measurements and list other indications to consider an evaluation for CM. We provide a differential diagnosis of genetic conditions associated with CM, classified as inborn errors of metabolism, malformation syndromes, neuromuscular diseases, and familial isolated CM disorders. A diagnostic strategy is offered that is based on the clinical presentation: biochemical abnormalities, encephalopathy, dysmorphic features or multiple malformations, neuromuscular disease, apparently isolated CM, and pathological specimen findings. Adjunctive treatment measures are recommended for severely ill patients in whom a metabolic cause of CM is suspected. A protocol is provided for the evaluation of moribund patients.

CONCLUSIONS

In summary, we hope to assist pediatric cardiologists and other subspecialists in the evaluation of children with CM for a possible genetic cause using a presentation-based approach. This should increase the percentage of children with CM for whom a diagnosis can be established, with important implications for treatment, prognosis, and genetic counseling.

Previously apparently undescribed syndrome: shallow orbits, ptosis, coloboma, trigonocephaly, gyral malformations, and mental and growth retardation

We describe 2 children with severe ptosis, trigonocephaly, broad nasal bridge, and major brain malformation. A total of 8 children have been reported who share most of these findings. Two of the individuals have had identical pericentric inversions involving chromosome 2p12-q14. These cases appear to represent a unique malformation syndrome.

Further delineation of the branchio-oculo-facial syndrome

We review 43 patients (15 new, 28 literature) with the branchio-oculo-facial (BOF) syndrome, which has a distinctive phenotype ranging from mild to severe forms, consisting of eye, ear, oral, and craniofacial anomalies. Virtually ubiquitous and possibly pathognomonic are the cervical/infra-auricular skin defects. Much less common are supra-auricular defects occurring as isolated anomalies or with cervical defects. Regardless of location, these lesions may have aplastic, "hemangiomatous," or otherwise abnormal overlying skin, and draining sinus fistulae. Renal malformations are frequent, but congenital heart and central nervous system defects are rare. Psychomotor performance is usually normal, but development delays, hypotonia, and visual, hearing, and speech problems are common. Autosomal dominant inheritance seems likely. Overlap between the BOF and branchio-otorenal syndromes has been observed, but elucidation of its molecular basis is not yet available. This article also discusses 5 patients with atypical manifestations considered to be possibly affected or probably unaffected, who are sufficiently unusual to be excluded from the final data analysis.

Familial Brachmann-de Lange syndrome: further evidence for autosomal dominant inheritance and review of the literature

We report on a mother and daughter with the Brachmann-de Lange syndrome which supports the view that in some families this disorder is due to autosomal dominant inheritance. A review of the literature concerning autosomal and recessive inheritance of this syndrome is presented.

Further delineation of the Baller-Gerold syndrome

Three new patients with the Baller-Gerold syndrome bring the number of reported cases to 20. In addition to craniosynostosis involving various sutures and preaxial reduction defects of variable severity, affected patients may have anal, urogenital, cardiac, central nervous system, and vertebral defects. Autosomal recessive inheritance is supported by the presence of affected sibs and parental consanguinity.

Nager acrofacial dysostosis: male-to-male transmission in 2 families

We describe 2 unrelated families with male-to-male transmission of Nager syndrome. All 5 affected individuals have moderate expression of the phenotype. One affected boy also has Hirschsprung disease. Although Nager acrofacial dysostosis usually occurs sporadically, both recessive and dominant inheritance have been suggested on the basis of reported familial cases. The 2 families described here with father-to-son transmission strongly support the hypothesis that some cases of Nager acrofacial dysostosis occur in individuals who are heterozygous for dominantly expressed, autosomal mutations.

Two additional patients representing the possible human homologue for the mouse mutant disorganisation (Ds)

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Beemer-Langer syndrome with manifestations of an orofaciodigital syndrome

We report on an infant girl with hydrops, macrocephaly, high forehead, flat face, hypertelorism, broad nasal bridge, median cleft lip and alveolar ridge, grooved palate, accessory frenula, small tongue, milia, severe rib and limb shortness, brachydactyly, talipes equinovarus, Dandy-Walker malformation, accessory spleen, unfixed mesentery, ectopic pancreas, and renal cysts. This patient resembles seven previously reported patients with the Beemer-Langer syndrome, a distinct lethal short rib syndrome characterized by hydrops, markedly short ribs and limbs, median cleft lip with or without cleft palate, flat face, and macrocephaly. Polydactyly is usually absent. Our patient's oral anomalies suggest an orofaciodigital syndrome, but the severe rib and limb shortness distinguish it from those disorders.

The branchio-oculo-facial syndrome

We review 13 reported cases and add the evaluations of 2 new patients with the branchio-oculo-facial (BOF) syndrome, a recently delineated autosomal dominant disorder with highly variable expression. This condition has a distinctive phenotype with characteristic craniofacial abnormalities consisting of aplastic or hemangiomatous cervical skin lesions with or without branchial sinuses; malformed, rotated auricles; and ocular abnormalities, which include microphthalmia or anophthalmia, coloboma, and cataract. The term pseudocleft has been used to describe the upper lip and philtrum abnormality found in mild cases, but the expression may extend to that of a complete cleft lip and palate. This unique disorder may go undetected in patients followed in cleft palate or craniofacial clinics and may not be recognized in patients with mild expressions. Genetic counseling for affected individuals is imperative because of the 50 percent recurrence risk. We emphasize the multidisciplinary care required to correct their craniofacial anomalies.

Central nervous system malformations in the CHARGE association

Of 144 patients with the CHARGE association (literature 136, new patients 8), 47 (33%) had either a postmortem examination (30) or computerized axial tomography scan (17) of the head. Twenty-six of 47 (55%) had definite central nervous system (CNS) malformations; arhinencephaly, with or without other defects (11), holoprosencephaly (2), holoprosencephaly with arhinencephaly (1), other forebrain defects (3), hindbrain defects (3), or other defects (6). The presence of CNS malformation was most strongly associated with choanal atresia. This review demonstrates a predominance of forebrain anomalies, particularly arhinencephaly and holoprosencephaly, which may provide a clue to the mechanism of abnormal morphogenesis involved in CHARGE association.

Absent aortic valve: a complex anomaly

Seven patients (four previously cited and three new cases) with absent aortic valve cusps (leaflets), a rare and underrecognized complex congenital heart defect, are discussed. All patients were male, six full-term and one premature with nonimmunologic hydrops. None underwent operation; all died within the first week of life from low cardiac output and hypoxemia. In most instances, the only remnant of the aortic valve was a nonobstructive fibrous ridge; occasionally, it was accompanied by rudimentary leaflets or sinuses of Valsalva. Absent aortic valve was associated with other significant structural malformations in all instances, including atrioventricular valve atresia, hypoplasia or dysplasia, less commonly double outlet right ventricle, abnormal pulmonary venous connection, or left ventricular endomyocardial abnormalities. Recognition of this unusual lesion is important since it is associated with other complex malformations, causes hypoxemia (for which early positive pressure ventilation is indicated), and could be possibly palliated using the right ventricle as the systemic ventricle.

Congenital heart defects in malformation syndromes

This article presents a comprehensive review of the type and frequency of congenital heart defects found in malformation syndromes which have been categorized by etiology. Certain cardiac phenotypes can be as helpful in identifying certain syndromes as can be seen with the more familiar facial, body, and behavioral phenotypes. An awareness of syndromes with a higher risk of congenital heart defect, and knowledge concerning heart defects which are distinctive for certain syndromes, focuses prenatal diagnosis efforts and fetal echocardiography. By using a mechanistic classification in which congenital heart defects are regarded as families of related defects rather than individual lesions, patterns can be recognized among different syndromes.

Persistent hyperplastic primary vitreous with vertical transmission

The authors report a 15-month-old white male and his 30-year-old mother who both have persistent hyperplastic primary vitreous (PHPV) unassociated with other congenital anomalies. Although there are two previous reports of PHPV in siblings suggesting autosomal recessive inheritance, this is the first report compatible with autosomal dominant inheritance.