Molecular and clinical analysis of Ellis-van Creveld syndrome in the United Arab Emirates

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.

Microdeletion of 4p16.2 in Children: A Case Report and Literature Review

Copy number variations (CNV) are thought to play an important role in causing human diseases, including congenital anomalies, psychiatric disorders, and intellectual disabilities. We report here a one-year-old boy presented to our clinic as developmental delay. He presented a birth weight of 4.5 kg, motor delay, mental retardation, mild hypertonia, and some dysmorphic features (mild frontal bossing, hypertelorism, epicanthus, concave nasal ridge, slightly sparse hair, short hands, and mild nail dysplasia). The brain MRI indicated brain abnormalities; the Gross Motor Function Measure-66 score was 23.37; the Gesell test result showed the development quotient was 50, suggesting mental retardation. Chromosomal microarray analysis showed an approximately 97 kb microdeletion at 4p16.2 (4p16.2 CNV), including part of EVC and EVC2 genes, which were associated with Ellis-van Creveld syndrome (EvC) and Weyers acrofacial dysostosis (WAD). This report suggests 4p16.2 microdeletion may be associated with multiple developmental abnormalities, including motor delay and mental retardation.

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.

Specific variants in WDR35 cause a distinctive form of Ellis-van Creveld syndrome by disrupting the recruitment of the EvC complex and SMO into the cilium

Most patients with Ellis-van Creveld syndrome (EvC) are identified with pathogenic changes in EVC or EVC2, however further genetic heterogeneity has been suggested. In this report we describe pathogenic splicing variants in WDR35, encoding retrograde intraflagellar transport protein 121 (IFT121), in three families with a clinical diagnosis of EvC but having a distinctive phenotype. To understand why WDR35 variants result in EvC, we analysed EVC, EVC2 and Smoothened (SMO) in IFT-A deficient cells. We found that the three proteins failed to localize to Wdr35(-/-) cilia, but not to the cilium of the IFT retrograde motor mutant Dync2h1(-/-), indicating that IFT121 is specifically required for their entry into the ciliary compartment. Furthermore expression of Wdr35 disease cDNAs in Wdr35(-/-) fibroblasts revealed that the newly identified variants lead to Hedgehog signalling defects resembling those of Evc(-/-) and Evc2(-/-) mutants. Together our data indicate that splicing variants in WDR35, and possibly in other IFT-A components, underlie a number of EvC cases by disrupting targeting of both the EvC complex and SMO to cilia.

Ellis van Creveld Syndrome (EVCS) in an Iranian, Three-Year-old Girl: A Case Report

Ellis van Creveld syndrome (EVCS) is mainly characterized by dysplatic changes in skeletal structures along with variable inter- and intra-familial patterns. Shortening of bony structures such as ribs and limbs, postaxial polydactyly, and dysplastic teeth and nails are among the clinical presentation of this autosomal recessive disease.

Identification of one novel mutation in the EVC2 gene in a Chinese family with Ellis-van Creveld syndrome

Ellis-van Creveld syndrome (EvC) is a rare autosomal recessive skeletal dysplasia characterized by short limbs, short ribs, postaxial polydactyly, and dysplastic nails and teeth. It is caused by biallelic mutations in the EVC or EVC2 gene. Here, we identified a novel nonsense mutation p.W828X (c.2484G>A) in exon 14 and a recurrent nonsense mutation p. R399X (c.1195C>T) in exon 10 of EVC2 gene in a Chinese boy with EvC. Identification of a novel genotype in EvC will provide clues to the phenotype-genotype relations and may assist not only in the clinical diagnosis of EvC but also in the interpretation of genetic information used for prenatal diagnosis and genetic counseling.

Report of Two Siblings with Overlapping Features of Ellis-van Creveld and Weyers Acrodental Dysostosis

Skeletal dysplasias are a heterogenous group of disorders combining abnormalities in the skull and other skeletal bones. Weyers acrofacial dysostosis also known as Weyers acrodental dysostosis was first described in 1952, by Weyers, as a postaxial polydactyly, which had features distinct from, yet some in common with the Ellis-van Creveld Syndrome (EvC). Both the syndromes have been mapped to the same chromosome, 4p16. The cases reported here highlight the overlapping features of both syndromes, which are dissimilar in mode of inheritance and phenotypic severity, emphasizing the need for genetic analysis, to categorize these conditions.

Ellis van Creveld syndrome--a report of two siblings

Chondro-ectodermal dysplasia is a rare autosomal recessive disorder which affects the ectodermal, mesodermal and endodermal derivatives. There are numerous conditions reported under this title which include Ellis van Creveld syndrome. The oral findings include multiple gingivolabial frena, dental abnormality, malocclusion and hypodontia. The diagnosis of Ellis van Creveld syndrome is based on the presence of oral mucosal changes like notching of the lower alveolus, fusion of the upper lip and gingival mucosa; dental changes like oligodontia, conical shape of anterior teeth and occasional presence of neonatal teeth. The authors report a rare case of Ellis van Creveld syndrome occurring among two siblings with oral mucosal, dental and skeletal abnormalities.

Mutations of a country: a mutation review of single gene disorders in the United Arab Emirates (UAE)

The United Arab Emirates inhabitants are ethnically diverse, with ancestries from Arabia, Persia, Baluchistan, and Africa. However, the majority of the current five million inhabitants are expatriates from the Asian subcontinent, Middle Eastern, African, and European countries. Consanguineous marriages within most UAE subpopulations are still the norm, leading to the formation of isolates and higher frequencies of recessive conditions. The UAE is ranked sixth in terms of prevalence of birth defects, with more than 270 genetic disorders reported in the national population. The UAE has high frequencies of blood disorders including thalassemias, sickle cell disease, and G6PD. In addition, certain genetic conditions are relatively common including cystic fibrosis, Joubert, and Meckel syndromes. Furthermore, numerous rare congenital malformations and metabolic disorders have been reported. We review the single gene disorders that have been studied at the molecular level in the UAE (which currently stand at 76) and compile the mutations found. Several novel (p.S2439fs) mutations have been reported including c.7317delA in NF1, c.5C>T (p.A2V) in DKC1, c.1766T>A (p.I589N) in TP63, and c.2117G>T (p.R706L) in VLDLR. We hope that this review will form the basis to establish a UAE mutations database and serve as a model for the collection of mutations of a country.