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.

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.

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.

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.

Peripheral odontogenic fibroma in a child with Ellis-van Creveld syndrome: Case report.

INTRODUCTION: Ellis-van Creveld (EVC) syndrome is an autosomal recessive disorder predominantly characterized by a disproportionate dwarfism, ectodermal dysplasia, postaxial polydactyly, and congenital heart malformations and pulmonary hypoplasia. OBJECTIVE: In this article, we hereby present a case of a 6-year-old Brazilian boy with EVC syndrome who presented a rare oral lesion as well as a remarkable number of classical and uncommon oral and dental features. CASE REPORT: Clinical and radiographic examination revealed multiple enamel hypoplasia, teeth agenesis, conical teeth, lower canine rotation, bilateral posterior crossbite, taurodontism of deciduous and permanent molars and delayed tooth eruption, dental caries, and absent vestibular sulcus. Additionally, a whitish lobulated nodule located in the alveolar ridge in the anterior region of the mandible was noted. Anatomopathological examination was compatible with the diagnosis of peripheral odontogenic fibroma (POF). In a 10-month clinical follow-up, no signs of recurrence were observed. CONCLUSION: In view of the characteristic oral findings of EVC syndrome and the potential for recurrence of POF, the pediatric dentist plays an essential role in clinical follow-up, planning and preventive, and rehabilitative treatment.

A Rare Presentation of Postaxial Polydactyly in a 2-Year-Old Female with Ellis-van Creveld Syndrome.

Postaxial or ulnar polydactyly is the most common form of polydactyly that may present with the duplication of soft-tissue structures only or with additional bony involvement. Surgical excision is the only viable treatment option for postaxial polydactyly with bony involvement, and psychological or cosmetic reasons are the main rationale for treatment. Ellis-van Creveld syndrome (EVC) is a rare congenital disorder characterized by chondral and ectodermal dysplasia, particularly postaxial polydactyly. The exact prevalence of EVC is unknown, and fewer than 300 cases have been reported. We present a case of a 2-year-old Hispanic female with EVC who presented with bilateral postaxial polydactyly and complete duplication of the metacarpal and phalanges. We describe the presentation and treatment of this patient, who ultimately underwent staged resection of the duplicated digits with reconstruction of the abductor muscle.

EVC-EVC2 complex stability and ciliary targeting are regulated by modification with ubiquitin and SUMO.

Ellis van Creveld syndrome and Weyers acrofacial dysostosis are two rare genetic diseases affecting skeletal development. They are both ciliopathies, as they are due to malfunction of primary cilia, microtubule-based plasma membrane protrusions that function as cellular antennae and are required for Hedgehog signaling, a key pathway during skeletal morphogenesis. These ciliopathies are caused by mutations affecting the EVC-EVC2 complex, a transmembrane protein heterodimer that regulates Hedgehog signaling from inside primary cilia. Despite the importance of this complex, the mechanisms underlying its stability, targeting and function are poorly understood. To address this, we characterized the endogenous EVC protein interactome in control and Evc-null cells. This proteomic screen confirmed EVC's main known interactors (EVC2, IQCE, EFCAB7), while revealing new ones, including USP7, a deubiquitinating enzyme involved in Hedgehog signaling. We therefore looked at EVC-EVC2 complex ubiquitination. Such ubiquitination exists but is independent of USP7 (and of USP48, also involved in Hh signaling). We did find, however, that monoubiquitination of EVC-EVC2 cytosolic tails greatly reduces their protein levels. On the other hand, modification of EVC-EVC2 cytosolic tails with the small ubiquitin-related modifier SUMO3 has a different effect, enhancing complex accumulation at the EvC zone, immediately distal to the ciliary transition zone, possibly via increased binding to the EFCAB7-IQCE complex. Lastly, we find that EvC zone targeting of EVC-EVC2 depends on two separate EFCAB7-binding motifs within EVC2's Weyers-deleted peptide. Only one of these motifs had been characterized previously, so we have mapped the second herein. Altogether, our data shed light on EVC-EVC2 complex regulatory mechanisms, with implications for ciliopathies.

Ellis van creveld syndrome: Cardiac anomalies and anesthetic implications.

Ellis-Van Creveld syndrome (EVC), also known as mesoectodermal dysplasia, is a rare autosomal recessive disorder with a tetrad of clinical features, comprising dwarfism, polydactyly, ectodermal dysplasia with sparse hair, hypoplastic nails and enamel, hypodontia and conical teeth and congenital heart disease (CHD). We report an 18-year-old girl with short stature and polydactyly, who got admitted to our hospital with shortness of breath on exertion for the last 2 years. On echocardiography, a partial atrioventricular canal (AV canal) defect was diagnosed, which was repaired surgically. The patient had an uneventful perioperative period.

Prenatal whole exome sequencing identified two rare compound heterozygous variants in EVC2 causing Ellis-van Creveld syndrome.

BACKGROUND: Pathogenic mutations in EVC or EVC2 gene can lead to Ellis-van Creveld (EvC) syndrome, which is a rare autosomal recessive skeletal dysplasia disorder. This study aimed to determine pathogenic gene variations associated with EvC syndrome in fetuses showing ultrasound anomalies. METHODS: A 32-year-old pregnant woman from Quanzhou, China was investigated. In her pregnancy examination, the fetus exhibited multiple fetal malformations, including a narrow thorax, short limbs, postaxial polydactyly, cardiac malformations, and separation of double renal pelvis. Karyotype, chromosomal microarray analysis and whole exome sequencing were performed for prenatal genetic etiology analysis. RESULTS: Chromosome abnormalities and copy number variants were not observed in the fetus using karyotype and chromosomal microarray analysis. Using whole exome sequencing, two compound heterozygous variants NM_147127.5:c.[2484G>A(p.Trp828Ter)];[871-2_894del] in EVC2 gene were identified in the fetus as pathogenic variants inherited from parents. CONCLUSIONS: The study is the first to identify two rare compound variants in EVC2 gene in a Chinese family using whole exome sequencing. The application of whole-exome sequencing would be helpful in fetal etiological diagnosis with ultrasound anomalies.

A homozygous EVC mutation in a prenatal fetus with Ellis-van Creveld syndrome.

BACKGROUND: Ellis-van Creveld (EvC) syndrome, caused by variants in EVC, is a rare genetic skeletal dysplasia. Its clinical phenotype is highly diverse. EvC syndrome is rarely reported in prenatal stages because its presentation overlaps with other diseases. METHODS: A Chinese pedigree diagnosed with EvC syndrome was enrolled in this study. Whole-exome sequencing (WES) was applied in the proband to screen potential genetic variant(s), and then Sanger sequencing was used to identify the variant in family members. Minigene experiments were applied. RESULTS: WES identified a homozygous variant (NM_153717.3:c.153_174 + 42del) in EVC which was inherited from the heterozygous parents and confirmed by Sanger sequencing. Further experiments demonstrated that this variant disrupts the canonical splicing site and produces a new splicing site at NM_153717.3: c.-164_174del, which ultimately leads to a 337 bp deletion at the 3' end of exon 1 and loss of the start codon. CONCLUSION: This is the first reported case of EvC syndrome based on a splicing variant and detailed delineation of the aberrant splicing effect in the fetus. Our study demonstrates the pathogenesis of this new variant, expands the spectrum of EVC mutations, and demonstrates that WES is a powerful tool in the clinical diagnosis of diseases with genetic heterogeneity.

Identification of Compound Heterozygous EVC2 Gene Variants in Two Mexican Families with Ellis-van Creveld Syndrome.

BACKGROUND: Ellis-van Creveld syndrome (EvCS) is an autosomal recessive ciliopathy with a disproportionate short stature, polydactyly, dystrophic nails, oral defects, and cardiac anomalies. It is caused by pathogenic variants in the EVC or EVC2 genes. To obtain further insight into the genetics of EvCS, we identified the genetic defect for the EVC2 gene in two Mexican patients. METHODS: Two Mexican families were enrolled in this study. Exome sequencing was applied in the probands to screen potential genetic variant(s), and then Sanger sequencing was used to identify the variant in the parents. Finally, a prediction of the three-dimensional structure of the mutant proteins was made. RESULTS: One patient has a compound heterozygous EVC2 mutation: a novel heterozygous variant c.519_519 + 1delinsT inherited from her mother, and a heterozygous variant c.2161delC (p.L721fs) inherited from her father. The second patient has a previously reported compound heterozygous EVC2 mutation: nonsense mutation c.645G > A (p.W215*) in exon 5 inherited from her mother, and c.273dup (p.K92fs) in exon 2 inherited from her father. In both cases, the diagnostic was Ellis-van Creveld syndrome. Three-dimensional modeling of the EVC2 protein showed that truncated proteins are produced in both patients due to the generation of premature stop codons. CONCLUSION: The identified novel heterozygous EVC2 variants, c.2161delC and c.519_519 + 1delinsT, were responsible for the Ellis-van Creveld syndrome in one of the Mexican patients. In the second Mexican patient, we identified a compound heterozygous variant, c.645G > A and c.273dup, responsible for EvCS. The findings in this study extend the EVC2 mutation spectrum and may provide new insights into the EVC2 causation and diagnosis with implications for genetic counseling and clinical management.

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.

Surgical Outcome of Complex Knee Deformity Correction in a Girl With Ellis-van Creveld Syndrome: A Report of a Rare Case.

Ellis-van Creveld (EVC) syndrome is a rare inherited condition with inheritance, which is autosomal recessive in nature and is also described as skeletal dysplasia (chondroectodermal). The patients present with a grave genu valgum deformity which is a major challenge in orthopedics. The current case report presents a young girl of the juvenile age group who came with deformity over the bilateral lower limb with difficulty in walking and bilateral upper limb polydactyly. The patient underwent relevant investigations and examinations which were suggestive of bilateral genu valgum deformity. Since the deformity was significant, a corrective osteotomy with soft tissue release was planned followed by rehabilitative physiotherapy. Considering the extensive nature of the surgery, a staged procedure was planned. The patient on follow-up presented with a good range of motion and improved gait. Various treatment modalities have been described for the correction of the deformity but few of them are done in patients with EVC syndrome and they state varying results and high incidences of relapse. The present study focuses on corrective osteotomy with soft tissue release as a treatment modality and describes the outcome associated with the modality. Thus, stating that with proper planning and postoperative rehabilitation the patient can achieve a good functional outcome.

Ellis-Van Creveld Syndrome: A Rare Case Report of an Indian Child With Rare Cardiac Anomalies and Normal Intelligence.

Ellis-Van Creveld syndrome (EVCS) is an abnormal genetic condition of the EVC2 gene located on chromosome 4. In this case, the person presents with bone growth abnormalities, thus having a short stature, short arms and legs (more commonly the forearm and lower leg), a narrow chest with short ribs, polydactyly, spoon-shaped or malformed nails, abnormalities in dentition, and congenital heart defects like atrial septal defects and ventricular septal defects. In this case report, we present a 4.5-year-old female child who presented with cough and cyanosis as signs and tachypnea, tachycardia, facial oedema, cold, and clubbing as symptoms with polydactyly and short stature focuses on a rare presentation of a syndromic disease known as EVCS.

Repair of double orifice mitral valve with an atrioventricular septal defect in a girl with Ellis-Van Creveld syndrome.

Ellis-van Creveld syndrome is a rare autosomal recessive disorder caused by mutations in the EVC and EVC2 genes. The four principal manifestations are chondrodysplasia, polydactyly, ectodermal dysplasia, and congenital heart defects. We describe the case of a 7-year-old girl with Ellis-van Creveld Syndrome with the diagnosis of common atrium and partial atrioventricular septal defect. She underwent a successful surgical repair, and intraoperatively, a double orifice mitral valve was diagnosed as well. The correct diagnosis of this disorder in early life is essential in the overall prognosis of the syndrome. Clinical follow-up at regular intervals is very important in these patients to institute proper managements and prevent further complications.

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.

Dental Anomalies in Ciliopathies: Lessons from Patients with BBS2, BBS7, and EVC2 Mutations.

Objective: To investigate dental anomalies and the molecular etiology of a patient with Ellis−van Creveld syndrome and two patients with Bardet−Biedl syndrome, two examples of ciliopathies. Patients and Methods: Clinical examination, radiographic evaluation, whole exome sequencing, and Sanger direct sequencing were performed. Results: Patient 1 had Ellis−van Creveld syndrome with delayed dental development or tooth agenesis, and multiple frenula, the feature found only in patients with mutations in ciliary genes. A novel homozygous mutation in EVC2 (c.703G>C; p.Ala235Pro) was identified. Patient 2 had Bardet−Biedl syndrome with a homozygous frameshift mutation (c.389_390delAC; p.Asn130ThrfsTer4) in BBS7. Patient 3 had Bardet−Biedl syndrome and carried a heterozygous mutation (c.389_390delAC; p.Asn130ThrfsTer4) in BBS7 and a homozygous mutation in BBS2 (c.209G>A; p.Ser70Asn). Her clinical findings included global developmental delay, disproportionate short stature, myopia, retinitis pigmentosa, obesity, pyometra with vaginal atresia, bilateral hydronephrosis with ureteropelvic junction obstruction, bilateral genu valgus, post-axial polydactyly feet, and small and thin fingernails and toenails, tooth agenesis, microdontia, taurodontism, and impaired dentin formation. Conclusions: EVC2, BBS2, and BBS7 mutations found in our patients were implicated in malformation syndromes with dental anomalies including tooth agenesis, microdontia, taurodontism, and impaired dentin formation.

Ellis-van Creveld Syndrome 2 With Novel Partial Exon 11 Deletion: A Case From Saudi Arabia.

Ellis-van Creveld syndrome (EVC) is a rare genetic disorder characterized by chondral and ectodermal dysplasia. Clinical features may include polydactyly, growth retardation, short ribs, and heart defects. The exact prevalence is still unclear; however, the Amish community in the United States is the most common community to report this rare disease. Until now, only six cases have been reported in Saudi Arabia so far. This is the first case to be reported in the Jazan region. Jazan covers an area of 11,671 km² and has a population of 1,567,547 at the 2017 census. This region has the highest population density with a high consanguinity marriage rate. We present a case of EVC with typical clinical findings, which was confirmed by homozygous mutation in the EVC2 gene in the region of Jazan, Saudi Arabia. Besides the six cases that were reported from Saudi Arabia, this makes it a total of seven cases. The prenatal findings are considered a good predictor of the disease outcome. More effort is needed in making a national registry of rare disorders to report such cases and provide more awareness among highly consanguinity marriage communities.