Ellis-van Creveld syndrome: prenatal diagnosis, molecular analysis and genetic counseling

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.

Establishing an objective clinical spectrum, genotype-phenotype correlations, and CRMP1 as a modifier in the Ellis-van Creveld syndrome: The first systematic review of EVC- and EVC2-associated conditions

Purpose

Ellis-van Creveld (EVC) syndrome is an autosomal recessive skeletal ciliopathy that was first identified in the Old Order Amish. Since its discovery, two causal genes have been identified, EVC and EVC2, showing that several cases were misdiagnosed and were, in fact, other entities. Nevertheless, there has not been any adequate phenotypic characterization of molecularly defined EVC syndrome so far.

Methods

We performed a systematic review of case reports of EVC syndrome with molecular confirmation of pathogenic variants in EVC or EVC2. Demographic, genetic, and clinical information of patients was assessed.

Results

We reviewed 725 papers and obtained 54 case reports/series that met the inclusion criteria, with a total subject sample of 310. Of these, 190 had biallelic variants, whereas 28 were affected heterozygotes. Our analysis revealed new phenotypes that have not been classically linked to the syndrome and others that have been linked but are very rare. Monoallelic symptomatic forms had less expressivity, and biallelic cases were milder if associated with EVC and/or missense variants. Finally, we identified CRMP1, a gene whose coding region partially overlaps with EVC, as a potential genetic modifier of the severity of the EVC syndrome.

Conclusion

We provided the first objective clinical characterization of molecularly defined EVC syndrome and identified the first associated genetic modifier, CRMP1, which had not been implicated in human disease before.

Genetic analysis of 55 cases with fetal skeletal dysplasia

BACKGROUND

Fetal skeletal dysplasia (SD) is a common congenital disability comprising a complex group of skeletal disorders with substantial clinical and genetic heterogeneity. Many of these defects are detected prenatally using ultrasound (US). However, the diagnostic accuracy of the US is limited.

METHODS

We recruited 55 unrelated fetuses with US-detected skeletal anomalies and performed sequential tests using copy number variation sequencing, targeted skeletal gene panel sequencing, or whole exome sequencing. The detected variants were validated using Sanger sequencing or multiplex ligation-dependent probe amplification. We conducted breakpoint analysis and structural modeling of variants possibly involved in fetal SD.

RESULTS

A definitive diagnosis was achieved in 81.82% of affected fetuses (45/55). We identified chromosomal abnormalities in seven cases and 36 variants, of which 18 were novel pathogenic or likely pathogenic in 11 genes in 38 cases. De novo variants were identified in 27 cases (71.05%, 27/38), and one gonosomal mosaicism variant was found in the mother of one fetus. Our case examples demonstrated the high heterogeneity of fetal SDs and the rare fetal SD-associated challenges.

CONCLUSIONS

Careful clinical evaluation of fetuses with SD can guide appropriate molecular testing. Our study extends the SD-associated pathogenic variant spectrum and provides useful genetic counselling guidance and an accurate prenatal diagnosis strategy.

Clustering of Genetic Anomalies of Cilia Outer Dynein Arm and Central Apparatus in Patients with Transposition of the Great Arteries

Transposition of the great arteries (TGA) is a congenital heart defect with a complex pathogenesis that has not been fully elucidated. In this study, we performed whole-exome sequencing (WES) in isolated TGA-diagnosed patients and analyzed genes of motile and non-motile cilia ciliogenesis and ciliary trafficking, as well as genes previously associated with this heart malformation. Deleterious missense and splicing variants of genes DNAH9, DNAH11, and ODAD4 of cilia outer dynein arm and central apparatus, HYDIN, were found in our TGA patients. Remarkable, there is a clustering of deleterious genetic variants in cilia genes, suggesting it could be an oligogenic disease. Our data evidence the genetic diversity and etiological complexity of TGA and point out that population allele determination and genetic aggregation studies are required to improve genetic counseling.

Ellis–van Creveld Syndrome in Iran, a Case Report and Review of Disease Cases in Iran, Middle East

Introduction:

Chondroectodermal dysplasia (Ellis–van Creveld syndrome (EVC)) (OMIM: #225500) is a rare skeletal dysplasia with unknown exact prevalence. EVC patients may have abnormal skeletal and extra skeletal symptoms. We report a case of EVC patient and review previous cases reported in Iran.

Materials and methods:

The patient was a 30 years old woman referred to our hand clinic for an extra finger in both hands. She was born to a consanguineous marriage. The patient had a history of bilateral valgus deformity of the knees, for which she underwent proximal tibial and distal femoral osteotomy. Upon examination, the patient had bilateral polydactyly and brachymetacarpia with hypotrophic fingernails. She was about 120 cm tall and had acromesomelic type dwarfism. Oral examination revealed serrated incisal margins, dental transposition, a diastema, conical teeth and, enamel hypoplasia. In the radiographic examination of upper extremity, postaxial polydactyly and polymetacarpia, enlarged distal radius, and fusion of capitate and hamate were seen. We searched online databases (Pubmed, Scopus, Google Scholar) and found 14 Iranian papers with 21 reported patients (there was no time limit). We reviewed available clinical and genetic data and the geographic origins of patients.

Results:

14 articles reporting 22 EVC patients (including our patient) from Iran have been published in Persian and English (7 in Persian and 7 in English). All patients presented with characteristic EVC symptoms but were diagnosed at a relatively late age, 18 patients were born to consanguineous marriages

Conclusions:

It seems that based on these studies, it is possible to identify some families with this genetic mutation. We can warn such families of the dangers of consanguineous marriage through genetic counseling before marriage. In addition, by identifying families with such problems, we can detect such anomalies in the baby earlier with more careful prenatal care.

Ellis-van Creveld syndrome: Report of a case and recurrent variant

BACKGROUND

Ellis-van Creveld syndrome (EvCS) is a rare autosomal recessive skeletal dysplasia that is characterized by short stature, short limbs, short ribs, polydactyly and structural heart defect. Despite locus heterogeneity, in the majority of the cases, the disorder segregates with mutations in the EVC and EVC2 genes, notably mutations with truncating protein as a final sequence. In the present study, we report the prenatal findings and genetic analysis of a terminated pregnancy affected by severe thoracic and skeletal dysplasia.

METHODS

After detailed physical and clinical examination, whole exome sequencing (WES) was performed and the variant was confirmed by Sanger sequencing.

RESULTS

One homozygote variant in EVC2 gene was identified in the fetus (NM_147127, c.942G>A, p.W314X). The EVC2 gene is strongly associated with EvCS, which is consistent with the sonographic findings of the fetus.

CONCLUSIONS

The homozygous p.W314X mutation found in this family was recently reported to be segregated in a consanguineous family originating from Pakistan. The occurrence of the p.W314X mutation in two unrelated families (Iranian and Pakistani) may be the result of an old founder effect or arose because of a mutational hotspot and is supporting evidence for the pathogenicity of this variant. Because skeletal dysplasia belongs to a broad spectrum of syndromes and therefore exhibits considerable background locus and allelic heterogeneity, our report highlights the need for appropriate genetic counseling and supports the feasibility of WES to determine an accurate diagnosis, as well as precise recurrence risk prediction.

Identification of a novel EVC variant in a Han-Chinese family with Ellis-van Creveld syndrome

Background

Ellis‐van Creveld syndrome (EVC), a very rare genetic skeletal dysplasia, is clinically characterized by a tetrad consisting of chondrodystrophy, polydactyly, ectodermal dysplasia, and cardiac anomalies. The aim of this study was to identify the genetic defect for EVC in a five‐generation consanguineous Han‐Chinese pedigree.

Methods

A five‐generation, 12‐member Han‐Chinese pedigree was enrolled in this study. Exome sequencing was applied in the proband to screen potential genetic variant(s), and then Sanger sequencing was used to identify the variant in family members and 200 unrelated ethnicity‐matched controls.

Results

A novel homozygous variant, c.2014C>T, p.(Q672*), in the EvC ciliary complex subunit 1 gene (EVC), was detected in the patient, which was cosegregated with the disease in the family and absent in the controls.

Conclusion

The identified novel homozygous EVC variant, c.2014C>T, p.(Q672*), was responsible for EVC in this Han‐Chinese pedigree. The findings in this study extend the EVC mutation spectrum and may provide new insights into EVC causation and diagnosis with implications for genetic counseling and clinical management.

Truncation and microdeletion of EVC/EVC2 with missense mutation of EFCAB7 in Ellis-van Creveld syndrome

Ellis-van Creveld syndrome (EvC) is a ciliopathy with cardiac anomalies, disproportionate short stature, polydactyly, dystrophic nails and oral defects. To obtain further insight into the genetics of EvC, we screened EVC/EVC2 mutations in eight Vietnamese EvC patients. All the patients had a congenital heart defect with atypical oral and/or skeletal abnormalities. One had compound heterozygous EVC2 mutations: a novel mutation c.769G > T-p.E177X in exon 6 inherited from father and another previously reported c.2476C > T-p.R826X mutation in exon 14 inherited from mother. The EVC2 mRNA expression level was significantly lower in the patient and her parents compared to controls. Another case had a novel heterozygous EVC mutation (c.1717C > G-p.S572X) in exon 12, inherited from his father. Of note, the mother without any EVC mutation on Sanger sequencing showed a lower expression level of EVC mRNA compared with controls. SNP array analysis revealed that the patient and mother had a heterozygous 16.4 kb deletion in EVC. This patient also had a heterozygous novel variant in exon 9 of EFCAB7 (c.1171 T > C-p.Y391H), inherited from his father. The atypical cardiac phenotype of this patient and the father suggested that EFCAB7 may modify the phenotype by interacting with EVC. In conclusion, we detected two novel nonsense mutations and a partial deletion of EVC/EVC2 in two Vietnamese families with EvC. Moreover, we found in one family a missense mutation of EFCAB7, a possible modifier gene in EvC and its related disorders.

Oral and craniofacial manifestations of Ellis-van Creveld syndrome: Case series

PURPOSE

The objective of this case series was to determine the oral, dental and craniofacial features of patients with EvC syndrome.

MATERIAL AND METHODS

Eight patients with EvC syndrome were enrolled. A complete family history, pedigree analysis, detailed medical history were collected. Findings of clinical examination, including craniofacial and orodental manifestations, and radiological investigations were thoroughly studied.

RESULTS

All eight patients had characteristic face, hypertrophic frenulum, conical and peg-shaped teeth, hypodontia of deciduous and/or permanent teeth and also skeletal dysplasia, small chest, short stature and hypoplastic nails. Additionally dysmorphic filtrum, serrated appearance of gingiva, diastema, enamel hypoplasia, microdontia, taurodontism, single rooted permanent molar, delayed eruption and high caries rate were observed with varying degrees. Cephalometric evaluation revealed skeletal Class III growth pattern in four subjects and Class II growth pattern in one subject.

CONCLUSION

Evaluation of craniofacial and orodental anomalies of EvC syndrome is required for accurate differential diagnosis from other congenital syndromes.

Deletion in the EVC2 gene causes chondrodysplastic dwarfism in Tyrolean Grey cattle

During the summer of 2013 seven Italian Tyrolean Grey calves were born with abnormally short limbs. Detailed clinical and pathological examination revealed similarities to chondrodysplastic dwarfism. Pedigree analysis showed a common founder, assuming autosomal monogenic recessive transmission of the defective allele. A positional cloning approach combining genome wide association and homozygosity mapping identified a single 1.6 Mb genomic region on BTA 6 that was associated with the disease. Whole genome re-sequencing of an affected calf revealed a single candidate causal mutation in the Ellis van Creveld syndrome 2 (EVC2) gene. This gene is known to be associated with chondrodysplastic dwarfism in Japanese Brown cattle, and dwarfism, abnormal nails and teeth, and dysostosis in humans with Ellis-van Creveld syndrome. Sanger sequencing confirmed the presence of a 2 bp deletion in exon 19 (c.2993_2994ACdel) that led to a premature stop codon in the coding sequence of bovine EVC2, and was concordant with the recessive pattern of inheritance in affected and carrier animals. This loss of function mutation confirms the important role of EVC2 in bone development. Genetic testing can now be used to eliminate this form of chondrodysplastic dwarfism from Tyrolean Grey cattle.

First-trimester prenatal diagnosis of Ellis-van Creveld syndrome

OBJECTIVE

To present the perinatal findings and first-trimester molecular and transabdominal ultrasound diagnosis of a fetus with Ellis-van Creveld (EvC) syndrome.

CASE REPORT

A 35-year-old woman was referred for genetic counseling at 13 weeks of gestation because of a family history of skeletal dysplasia. She had experienced one spontaneous abortion, and delivered one male fetus and one female fetus with EvC syndrome. During this pregnancy, a prenatal transabdominal ultrasound at 13(+4) weeks of gestation revealed a nuchal translucency (NT) thickness of 2.0 mm, an endocardial cushion defect, postaxial polydactyly of bilateral hands, and mesomelic dysplasia of the long bones. Amniocentesis was performed at 13(+5) weeks of gestation. Results of a cytogenetic analysis revealed a karyotype of 46,XX and that of a molecular analysis revealed compound heterozygous mutations of c.1195C>T and c.871-2_894del26 in the EVC2 gene. Prenatal ultrasound at 16 weeks of gestation showed a fetus with short limbs, an endocardial cushion defect, and postaxial polydactyly of bilateral hands. The parents decided to terminate the pregnancy, and a 116-g female fetus was delivered with a narrow thorax, shortening limbs, and postaxial polydactyly of the hands.

CONCLUSION

Prenatal diagnosis of an endocardial cushion defect with postaxial polydactyly should include a differential diagnosis of EvC syndrome in addition to short rib-polydactyly syndrome, Bardet-Biedl syndrome, orofaciodigital syndrome, Smith-Lemli-Opitz syndrome, and hydrolethalus syndrome.

Short rib-polydactyly syndrome type II (Majewski): prenatal diagnosis, perinatal imaging findings and molecular analysis of the NEK1 gene

OBJECTIVE

To demonstrate perinatal imaging findings and to investigate the mutation in the NEK1 gene in a fetus with type II short rib-polydactyly syndrome (SRPS) (Majewski).

CASE REPORT

A 34-year-old woman with a past history of fetal SRPS was referred to the hospital at 16 weeks of gestation because of sonographic diagnosis of short limbs in the fetus. Fetal ultrasound revealed short ribs, short limbs, absence of tibiae, polydactyly, syndactyly and choroid plexus cysts. At 21 weeks of gestation, polycystic kidneys were found. The pregnancy was terminated, and a fetus was delivered with facial dysmorphism, a median cleft lip, a narrow chest, micromelia, aplasia of tibiae, hypoplastic nails, syndactyly and postaxial polydactyly. The karyotype was 46,XX. Molecular analysis of fetal tissues showed a paternal-origin heterozygous splice site mutation in intron 7 (c.465-1 G>A) in the NEK1 gene, but no mutations in the genes of WDR35, DYNC2H1, IFT80, EVC and EVC2. The NEK1 mutation causes an alteration of the splice acceptor site of intron 7 (IVS7-1 G>A). No second mutation was identified.

CONCLUSION

Tibial aplasia, choroid plexus cysts and polycystic kidneys can be prominent prenatal ultrasound findings of type II SRPS. The present case provides evidence for a correlation of NEK1 mutation with type II SRPS.