Human Genetics of Tricuspid Atresia and Univentricular Heart.

Tricuspid atresia (TA) is a rare congenital heart condition that presents with a complete absence of the right atrioventricular valve. Because of the rarity of familial and/or isolated cases of TA, little is known about the potential genetic abnormalities contributing to this condition. Potential responsible chromosomal abnormalities were identified in exploratory studies and include deletions in 22q11, 4q31, 8p23, and 3p as well as trisomies 13 and 18. In parallel, potential culprit genes include the ZFPM2, HEY2, NFATC1, NKX2-5, MYH6, and KLF13 genes. The aim of this chapter is to expose the genetic components that are potentially involved in the pathogenesis of TA in humans. The large variability in phenotypes and genotypes among cases of TA suggests a genetic network that involves many components yet to be unraveled.

Human Genetics of Ventricular Septal Defect.

Ventricular septal defects (VSDs) are recognized as one of the commonest congenital heart diseases (CHD), accounting for up to 40% of all cardiac malformations, and occur as isolated CHDs as well as together with other cardiac and extracardiac congenital malformations in individual patients and families. The genetic etiology of VSD is complex and extraordinarily heterogeneous. Chromosomal abnormalities such as aneuploidy and structural variations as well as rare point mutations in various genes have been reported to be associated with this cardiac defect. This includes both well-defined syndromes with known genetic cause (e.g., DiGeorge syndrome and Holt-Oram syndrome) and so far undefined syndromic forms characterized by unspecific symptoms. Mutations in genes encoding cardiac transcription factors (e.g., NKX2-5 and GATA4) and signaling molecules (e.g., CFC1) have been most frequently found in VSD cases. Moreover, new high-resolution methods such as comparative genomic hybridization enabled the discovery of a high number of different copy number variations, leading to gain or loss of chromosomal regions often containing multiple genes, in patients with VSD. In this chapter, we will describe the broad genetic heterogeneity observed in VSD patients considering recent advances in this field.

Ellis-van Creveld syndrome: a case report.

Ellis-van Creveld syndrome (EVC), also known as chondroectodermal dysplasia, is a rare entity. It most commonly affects the tubular bones leading to dwarfism and a long trunk with ossification defects. Other presentations are wide hands and feet, dysplastic nails, thin hair, and cardiac malformations. An eight-year-old female patient presented to our tertiary care centre with complaints of short stature, abnormal dentition, and fatigue. The child's parents were first-degree relatives. On radiological imaging, it was revealed that the patient had postaxial polydactyly, short stature, and genu valgum deformity along with mild cardiomegaly. All these features were indicative of Ellis-van Creveld syndrome. EVC is a rare clinical syndrome with a distinctive clinical presentation. It requires comprehensive radiological investigations and the management is best done with a multidisciplinary approach.

Germline and Mosaic Variants in PRKACA and PRKACB Cause a Multiple Congenital Malformation Syndrome.

PRKACA and PRKACB code for two catalytic subunits (Cα and Cß) of cAMP-dependent protein kinase (PKA), a pleiotropic holoenzyme that regulates numerous fundamental biological processes such as metabolism, development, memory, and immune response. We report seven unrelated individuals presenting with a multiple congenital malformation syndrome in whom we identified heterozygous germline or mosaic missense variants in PRKACA or PRKACB. Three affected individuals were found with the same PRKACA variant, and the other four had different PRKACB mutations. In most cases, the mutations arose de novo, and two individuals had offspring with the same condition. Nearly all affected individuals and their affected offspring shared an atrioventricular septal defect or a common atrium along with postaxial polydactyly. Additional features included skeletal abnormalities and ectodermal defects of variable severity in five individuals, cognitive deficit in two individuals, and various unusual tumors in one individual. We investigated the structural and functional consequences of the variants identified in PRKACA and PRKACB through the use of several computational and experimental approaches, and we found that they lead to PKA holoenzymes which are more sensitive to activation by cAMP than are the wild-type proteins. Furthermore, expression of PRKACA or PRKACB variants detected in the affected individuals inhibited hedgehog signaling in NIH 3T3 fibroblasts, thereby providing an underlying mechanism for the developmental defects observed in these cases. Our findings highlight the importance of both Cα and Cß subunits of PKA during human development.

Ellis-van Creveld syndrome in a neonate: a case report.

Ellis-Van Creveld Syndrome (EVC) is a rare genetic disorder with autosomal recessive inheritance, caused by mutations in two genes, EVC1 and EVC2 in the 4p16 chromosome. The exact prevalence of EVC is unknown and is estimated at approximately seven per million. It affects males and females equally. It is a constellation of four findings, including chondrodysplasia, polydactyly, ectodermal dysplasia, and congenital heart defects. Our case was unique as it had left inguinal hernia, short phallus, hyperpigmented scrotum, cryptorchidism, and other defining features of this syndrome. A multidisciplinary team managed this patient with regular follow up. Only six cases have been reported in Pakistan, and only one of them was reported in a neonate. This report highlights the importance of timely and proper multidisciplinary management of such disorders for better outcomes. It will also create awareness among medical professionals and will help them to identify promptly.

Role of primary cilia and Hedgehog signaling in craniofacial features of Ellis-van Creveld syndrome.

Ellis-van Creveld syndrome (EvC) is an autosomal recessive genetic disorder involving pathogenic variants of EVC and EVC2 genes and classified as a ciliopathy. The syndrome is caused by mutations in the EVC gene on chromosome 4p16, and EVC2 gene, located close to the EVC gene, in a head-to-head configuration. Regardless of the affliction of EVC or EVC2, the clinical features of Ellis-van Creveld syndrome are similar. Both these genes are expressed in tissues such as, but not limited to, the heart, liver, skeletal muscle, and placenta, while the predominant expression in the craniofacial tissues is that of EVC2. Biallelic mutations of EVC and EVC2 affect Hedgehog signaling and thereby ciliary function, crucial factors in vertebrate development, culminating in the phenotypical features characteristic of EvC. The clinical features of Ellis-van Creveld syndrome are consistent with significant abnormalities in morphogenesis and differentiation of the affected tissues. The robust role of primary cilia in histodifferentiation and morphodifferentiation of oral, perioral, and craniofacial tissues is becoming more evident in the most recent literature. In this review, we give a summary of the mechanistic role of primary cilia in craniofacial development, taking Ellis-van Creveld syndrome as a representative example.

An intrafamilial phenotypic variability in Ellis-Van Creveld syndrome due to a novel 27 bps deletion mutation.

Ellis-van Creveld (EvC) syndrome is an autosomal recessive disease, characterized by ectodermal, skeletal, and cardiac anomalies. We report intrafamilial phenotypic variability in three new EvC syndrome cases. Affected males in this study showed only ectodermal abnormalities, whereas an affected female showed the classical presentation of EvC Syndrome, including bilateral postaxial polydactyly of hands and feet, and congenital heart defects. Whole exome sequencing was performed to identify the causative variant, followed by validation and segregation analysis using Sanger sequencing. A homozygous deletion variant (c.731_757del) was identified in exon 6 of the EVC gene (NM_153717.2). The identified variant is considered to be the most likely candidate variant for the EvC syndrome in the family based on previous reports validating the role of EVC variants in the EvC syndrome. The disease correctly segregated in the family members, as all affected members were homozygous, and obligate carriers were heterozygous. Our family is remarkable in highlighting the variable expressivity of the EvC phenotype within the same family, due to a homozygous deletion mutation in the EVC gene. The variable expressivity might be due to the hypomorphic nature of mutation, or the presence of additional variants in modifier genes or in the regulatory regions of the EVC/EVC2 genes.

Rare clinical features of the Ellis van Creveld syndrome: A case report and literature review.

Ellis van Creveld syndrome (EVC) is a rare autosomal recessive disorder also called chondroectodermal dysplasia. This study reports on a 40-year-old woman from Iran with a syndromic appearance consisting of a coarse face, conical anterior teeth, dental agenesis and permanent teeth at birth, several small extralabial, nonmidline frenula with a high-arched palate, and a large maxillary labial frenulum. The patient had cyanosis on her lips since childhood and a history of adenoid tonsillectomy surgery. She also had androgenic alopecia, an elongated trunk with excessive lordosis and pectus excavatum, polycystic ovarian syndrome, and a history of two periods in a month. She also had multiple fibrocystic cysts in her breasts, lower extremity deformity, dysplastic genu valgum, and short limb dwarfism; she had undergone left knee surgery four times and had severe osteoporosis in some of her bones and some hyperpigmented patches on the dorsal of the left hand. Her hands and feet were also wide and markedly deformed with hypoplastic fingernails and toenails, and she had bimanual hexadactyly on the ulnar side of the hands. She also had a history of severe hypotension and cyanosis during surgery and suffered from congenital heart failure and had undergone open heart surgery for correcting her atrial heart defect. In this study pectus excavatum, Phrygian cap gallbladder, liver hemangioma, polycystic ovarian disease, and breast fibrocystic cysts was reported for first time in this case of EVC syndrome. This case was reported and all articles regarding common, uncommon, rare, and extremely rare presentations of this syndrome were reviewed.

Common atrium/atrioventricular canal defect and postaxial polydactyly: A mild clinical subtype of Ellis-van Creveld syndrome caused by hypomorphic mutations in the EVC gene.

Clinical expression of Ellis-van Creveld syndrome (EvC) is variable and mild phenotypes have been described, including patients with mostly cardiac and limb involvement. Whether these cases are part of the EvC phenotypic spectrum or separate conditions is disputed. Herein, we describe a family with vertical transmission of atrioventricular canal defect (AVCD), common atrium, and postaxial polydactyly. Targeted sequencing of EVC, EVC2, WDR35, DYNC2LI1, and DYNC2H1 identified different compound heterozygosity in EVC genotypes in the two affected members, consisting of a nonsense (p.Arg622Ter) and a missense (p.Arg663Pro) variant in the father, and the same nonsense variant and a noncanonical splice-site in-frame change (c.1316-7A>G) in the daughter. Complementary DNA sequencing, immunoblot, and immunofluorescence experiments using patient-derived fibroblasts and Evc-/- mouse embryonic fibroblasts showed that p.Arg622Ter is a loss-of-function mutation, whereas p.Arg663Pro and the splice-site change c.1316-7A>G are hypomorphic variants resulting in proteins that retain, in part, the ability to complex with EVC2. Our molecular and functional data demonstrate that at least in some cases the condition characterized as "common atrium/AVCD with postaxial polydactyly" is a mild form of EvC due to hypomorphic EVC mutations, further supporting the occurrence of genotype-phenotype correlations in this syndrome.

Ellis-van Creveld syndrome in a patient from Tanzania.

We report an African infant with Ellis-van Creveld (EVC) syndrome. EVC syndrome is a chondral and ectodermal dysplasia with autosomal recessive transmission. The baby presented with polydactyly, short limbs and atrioventricular septal defect, but was withdrawn from clinical follow up for the first year of life. Initial hematological abnormalities could not be explained and normalized later. EVC syndrome was confirmed by genetic analysis that showed two pathogenic mutations in the EVC2 gene, c.653_654del, p.Val218Glyfs*12 in exon 5, and c.2710C>T, p.Gln904* in exon 16. The variant c.653_654del; p.Val218Glyfs*12 in exon 5 has not been described before. Our review of medical literature suggested this is the first molecularly confirmed case of EVC syndrome in sub-Saharan Africa.

Biallelic mutations in DYNC2LI1 are a rare cause of Ellis-van Creveld syndrome.

Ellis-van Creveld syndrome (EvC) is a chondral and ectodermal dysplasia caused by biallelic mutations in the EVC, EVC2 and WDR35 genes. A proportion of cases with clinical diagnosis of EvC, however, do not carry mutations in these genes. To identify the genetic cause of EvC in a cohort of mutation-negative patients, exome sequencing was undertaken in a family with 3 affected members, and mutation scanning of a panel of clinically and functionally relevant genes was performed in 24 additional subjects with features fitting/overlapping EvC. Compound heterozygosity for the c.2T>C (p.Met1?) and c.662C>T (p.Thr221Ile) variants in DYNC2LI1, which encodes a component of the intraflagellar transport-related dynein-2 complex previously found mutated in other short-rib thoracic dysplasias, was identified in the 3 affected members of the first family. Targeted resequencing detected compound heterozygosity for the same missense variant and a truncating change (p.Val141*) in 2 siblings with EvC from a second family, while a newborn with a more severe phenotype carried 2 DYNC2LI1 truncating variants. Our findings indicate that DYNC2LI1 mutations are associated with a wider clinical spectrum than previously appreciated, including EvC, with the severity of the phenotype likely depending on the extent of defective DYNC2LI1 function.

Ellis-Van Creveld Syndrome and Dandy-Walker Malformation: An Uncommon Association.

Ellis-Van Creveld (EvC) syndrome is a rare autosomal recessive chondroectodermal dysplasia including chondrodysplasia, postaxial polydactyly, ectodermal dysplasia, and congenital heart disease in 60% of patients. Additional findings may be observed affecting the pulmonary, renal, gastrointestinal, hematologic, and central nervous systems. We report a case of an 11-year-old Moroccan boy with EVC syndrome and Dandy-Walker malformation. To our knowledge, this association has been previously reported in 3 patients in the literature.

Sleep-Disordered Breathing in Children with Rare Skeletal Disorders: A Survey of Clinical Records.

OBJECTIVE: Craniofacial disharmony in skeletal diseases is strongly associated with sleep-disordered breathing. This study was aimed at studying the sleep respiratory patterns in young children with rare skeletal disorders. DESIGN: This retrospective study included children with achondroplasia (ACH), osteogenesis imperfecta (OI) and Ellis van Creveld Syndrome. Our subjects underwent an in-laboratory overnight respiratory polygraph between January 2012 and April 2016. All medical records were reviewed and brain Magnetic Resonance Imaging was conducted on patients with ACH, nasopharynx, oropharynx and laryngopharynx spaces. PATIENTS: Twenty-four children were enrolled, 13 with ACH, 2 with spondyloepiphyseal dysplasia, 1 with odontochondrodysplasia, 6 with OI and 2 with Ellis van Creveld Syndrome. RESULTS: Children with ACH, who had adenotonsillectomy, showed fewer sleep respiratory involvement than untreated children. Among 13 patients with ACH, brain magnetic resonance imaging was available in 10 subjects and significant negative correlation was found between sleep respiratory patterns, nasopharynx and oropharynx space (p < 0.05). In 2 patients with spondyloepiphyseal dysplasia, mild-to-moderate sleep respiratory involvement was found. Both subjects had a history of adenotonsillectomy. Mild sleep respiratory involvement was also observed in 4 out of 6 patients with OI. One patient with Ellis van Creveld syndrome had mild sleep respiratory disturbance. CONCLUSIONS: Sleep respiratory disturbances were detected in children with ACH, and with less severity also in OI and Ellis van Creveld syndrome. Adenotonsillectomy was successful in ACH in reducing symptoms. In light of our findings, multicenter studies are needed to obtain further information on these rare skeletal diseases.

Management of Congenital Heart Disease Associated with Ellis-van Creveld Short-rib Thoracic Dysplasia.

OBJECTIVE: To evaluate clinical outcome of patients with Ellis-van Creveld syndrome (EVC) in whom congenital heart disease (CHD) repair was delayed intentionally to reduce the risk of postoperative respiratory morbidity and mortality. STUDY DESIGN: This retrospective review of 51 EVC c.1886+5G>T homozygotes born between 2005 and 2014 focused on 18 subjects who underwent surgery for CHD, subdivided into early (mean, 1.3 months) vs delayed (mean, 50.1 months) repair. RESULTS: Growth trajectories differed between control subjects and patients with EVC, and CHD was associated with slower weight gain. Relative to controls, infants with EVC had a 40%-75% higher respiratory rates (independent of CHD) accompanied by signs of compensated respiratory acidosis. Blood gases and respiratory rates approached normal values by age 4 years. Hemodynamically significant CHD was present in 23 children, 18 (78%) of whom underwent surgical repair. Surgery was performed at 1.3 ± 1.3 months for children born between 2005 and 2009 (n = 9) and 50.1 ± 40.2 months (P = .009) for children born between 2010 and 2014 (n = 9). The latter had shorter postoperative mechanical ventilation (1.1 ± 2.4 days vs 49.6 ± 57.1 days; P = .075), shorter intensive care duration of stay (16 ± 24 days vs 48.6 ± 44.2 days; P = .155), and no postoperative tracheostomies (vs 60%; P = .028) or deaths (vs 44%; P = .082). CONCLUSION: Among children with EVC and possibly other short-rib thoracic dysplasias, delayed surgical repair of CHD reduces postoperative morbidity and improves survival. Respiratory rate serves as a simple indicator for optimal timing of surgical repair.

Novel mutations in EVC cause aberrant splicing in Ellis-van Creveld syndrome.

Ellis-van Creveld syndrome (EvC) is a rare autosomal recessive disorder characterized by disproportionate chondrodysplasia, postaxial polydactyly, nail dystrophy, dental abnormalities and in a proportion of patients, congenital cardiac malformations. Weyers acrofacial dysostosis (Weyers) is another dominantly inherited disorder allelic to EvC syndrome but with milder phenotypes. Both disorders can result from loss-of-function mutations in either EVC or EVC2 gene, and phenotypes associated with the two gene mutations are clinically indistinguishable. We present here a clinical and molecular analysis of a Chinese family manifested specific features of EvC syndrome. Sequencing of both EVC and EVC2 identified two novel heterozygous splice site mutations c.384+5G>C in intron 3 and c.1465-1G>A in intron 10 in EVC, which were inherited from mother and father, respectively. In vitro minigene expression assay, RT-PCR and sequencing analysis demonstrated that c.384+5G>C mutation abolished normal splice site and created a new cryptic acceptor site within exon 4, whereas c.1465-1G>A mutation affected consensus splice junction site and resulted in full exon 11 skipping. These two aberrant pre-mRNA splicing processes both produced in-frame abnormal transcripts that possibly led to abolishment of important functional domains. To our knowledge, this is the first report of EVC mutations that cause EvC syndrome in Chinese population. Our data revealed that EVC splice site mutations altered splicing pattern and helped elucidate the pathogenesis of EvC syndrome.

Ellis-van Creveld syndrome associated with chronic intestinal pseudo-obstruction.

Ellis-van Creveld (EVC) syndrome is a rare autosomal recessive disorder characterized by hypoplastic nails, polydactyly, and achondroplasia. Patients usually exhibit normal cognitive function and no remarkable developmental delay. We herein present an unusual case of EVC syndrome. A Japanese 2-year-old boy was born at term, but immediately developed severe respiratory failure due to thorax deformity, postaxial polydactyly and nail hypoplasia. We identified a novel pattern of germinal compound heterozygous nonsense EVC2 mutations of c.1814C > A (p. S605X) and c.2653C > T (p. R885X), leading to the diagnosis of EVC syndrome. Interestingly, he also had severe developmental delay, and suddenly developed excessive abdominal distension at the age of 2. On surgery, extensive necrotic bowel with chronic intestinal pseudo-obstruction was noted. This is, to our knowledge, a most severe phenotype of EVC syndrome, illustrating that the specific pattern of EVC2 compound heterozygous mutations may cause severe developmental delay and intestinal malfunction.

Ellis-van Creveld Syndrome in Grey Alpine Cattle: Morphologic, Immunophenotypic, and Molecular Characterization.

Ellis-van Creveld (EvC) syndrome is a human autosomal recessive disorder caused by a mutation in either the EVC or EVC2 gene, and presents with short limbs, polydactyly, and ectodermal and heart defects. The aim of this study was to understand the pathologic basis by which deletions in the EVC2 gene lead to chondrodysplastic dwarfism and to describe the morphologic, immunohistochemical, and molecular hallmarks of EvC syndrome in cattle. Five Grey Alpine calves, with a known mutation in the EVC2 gene, were autopsied. Immunohistochemistry was performed on bone using antibodies to collagen II, collagen X, sonic hedgehog, fibroblast growth factor 2, and Ki67. Reverse transcription polymerase chain reaction was performed to analyze EVC1 and EVC2 gene expression. Autopsy revealed long bones that were severely reduced in length, as well as genital and heart defects. Collagen II was detected in control calves in the resting, proliferative, and hypertrophic zones and in the primary and secondary spongiosa, with a loss of labeling in the resting zone of 2 dwarfs. Collagen X was expressed in hypertrophic zone in the controls but was absent in the EvC cases. In affected calves and controls, sonic hedgehog labeled hypertrophic chondrocytes and primary and secondary spongiosa similarly. FGF2 was expressed in chondrocytes of all growth plate zones in the control calves but was lost in most EvC cases. The Ki67 index was lower in cases compared with controls. EVC and EVC2 transcripts were detected. Our data suggest that EvC syndrome of Grey Alpine cattle is a disorder of chondrocyte differentiation, with accelerated differentiation and premature hypertrophy of chondrocytes, and could be a spontaneous model for the equivalent human disease.

The extraordinary career of Professor Dr. Simon van Creveld.

Simon van Creveld received both the MD and PhD degrees and had a multifaceted medical and scientific education at many hospitals and research institutes in the Netherlands, Germany, and the UK. He and his wife were the first to develop insulin for the Netherlands. His major interests were in hemophilia and hemorrhagic disorders, which accounted for 87 of his publications. In 1934, van Creveld demonstrated that a dispersed protein fraction obtained from serum could reduce the clotting time of hemophilic blood. His interest in glycogen storage disease resulted in van Creveld-von Gierke disease for which van Creveld contributed four published articles. The Ellis-van Creveld syndrome, also known as chondroectodermal dysplasia, was published in 1940 and became well known to medical geneticists. During the Nazi occupation of the Netherlands, van Creveld's professorship was taken away from him because he was Jewish. His visits to hospitals of concentration camps to treat babies and give pediatric advice while wearing a Jewish Yellow Star and interacting with SS Commandants in charge, and then leaving can only be described as amazing. After the war, his professorship was returned, and in the same year as his retirement, he established a large Hemophila Treatment and Research Center now known as the Van Creveld Clinic, which celebrated its 40th anniversary in 2005.

Mexican patient with Ellis-van Creveld syndrome and cleft palate: Importance of functional hemizygosity and phenotype expansion.

BACKGROUND: Ellis-van Creveld syndrome (EvCS) is a chondroectodermal dysplasia caused by germline pathogenic variants in ciliary complex subunit 1 and 2 genes (EVC, EVC2) on chromosome 4p16.2. This disease has a broad phenotype, and there are few described phenotype-genotype correlations. METHODS: Ethical Compliance: Written informed consent was obtained from the parents. Here, we report a genetically confirmed Mexican patient with EvCS having two inherited pathogenic variants in trans in EVC2: c.[1195C>T];[2161delC]. RESULTS: This patient allowed a genotypic-phenotypic comparison with another Mexican subject who presented a more attenuated phenotype; furthermore, our patient also presented cleft palate, a rarely reported feature. CONCLUSION: Our case shows the importance of comparing functional hemizygosity between patient's phenotypes when they share a variant, and our case also supports the association of alterations in the palate as part of the EvCS phenotype.