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 (EVC) syndrome is an autosomal recessive chondrodysplasia. The affected individuals bear a series of skeleton defects, congenital heart septum anomalies, midfacial defects, and dental defects. Previous studies using Evc or Evc2 mutant mice have characterized the pathological mechanism leading to various types of congenital defects. Some patients with EVC have supernumerary tooth; however, it is not known yet if there are supernumerary tooth formed in Evc or Evc2 mutant mice, and if yes, what is the pathological mechanism associated. In the present study, we used Evc2 mutant mice and analyze the pattern of molars in Evc2 mutant mice at various stages. Our studies demonstrate that Evc2 loss of function within the dental mesenchymal cells leads to abnormal molar patterning, and that the most anterior molar in the Evc2 mutant mandible represents a supernumerary tooth. Finally, we provide evidence supporting the idea that both compromised Hedgehog signaling and elevated WNT signaling due to Evc2 loss of function contributes to the supernumerary tooth formation.

UNASSIGNED: To analyse the pathogenic genes in a patient with hypohidrotic ectodermal dysplasia (HED) and explore the relationship between pathogenic genes and the oligodontia phenotype.
UNASSIGNED: Clinical data and peripheral blood were collected from a patient with HED. Pathogenic genes were analysed by whole-exon sequencing (WES) and verified by Singer sequencing. The secondary and tertiary structures of the variant proteins were predicted to analyse their toxicity.
UNASSIGNED: The patient exhibited a severe oligodontia phenotype, wherein only two deciduous canines were left in the upper jaw. WES revealed a hemizygous EDA variant c.466C > T p.(Arg156Cys) and a novel heterozygous EVC2 variant c.1772T > C p.(Leu591Ser). Prediction of the secondary and tertiary structures of the EDA variant p.(Arg156Cys) and EVC2 variant p.(Leu591Ser) indicated impaired function of both molecules.
UNASSIGNED: The patient demonstrated a more severe oligodontia phenotype when compared with the other patients caused by the EDA variant c.466C > T. Since Evc2 is a positive regulator of the Sonic Hedgehog (Shh) signal pathway, we speculated that the EVC2 variant p.(Leu591Ser) may play a synergistic role in the oligodontia phenotype of HED, thereby exacerbating the oligodontia phenotype. Knowledge of oligodontia caused by multiple gene variants is of great significance for understanding individual differences in oligodontia phenotypes.

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.

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.

Ellis-van Creveld syndrome (EVC; MIM ID #225500) is a rare congenital disease with an occurrence of 1 in 60,000. It is characterized by remarkable skeletal dysplasia, such as short limbs, ribs and polydactyly, and orofacial anomalies. With two of three patients first noted as being offspring of consanguineous marriage, this autosomal recessive disease results from mutations in one of two causative genes: EVC or EVC2/LIMBIN. The recent identification and manipulation of genetic homologs in animals has deepened our understanding beyond human case studies and provided critical insight into disease pathogenesis. This review highlights the utility of animal-based studies of EVC by summarizing: (1) molecular biology of EVC and EVC2/LIMBIN, (2) human disease signs, (3) dysplastic limb development, (4) craniofacial anomalies, (5) tooth anomalies, (6) tracheal cartilage abnormalities, and (7) EVC-like disorders in non-human species.

UNASSIGNED: In Pakistan, 74% of consanguineous marriages are among the first cousins. Continuity of consanguineous marriages over generations increases the risk of recessive diseases such as deafness. The objective of this study was to investigate genetic origin of Pakistani deaf brothers with parents of consanguineous marriage.
UNASSIGNED: DNA was extracted from the blood through Qiagen kit. Paired-end sequencing library was prepared according to protocol of Illumina\'s TruSight Rapid Capture kit and TruSight Inherited Disease Panel. Library was normalized and used for Next Generation Sequencing through MiSeq. NGS data were analyzed using various bioinformatics tools.
UNASSIGNED: Both brothers were found to have novel deleterious mutation in MYO7A (c.2476G>A) while the younger brother had additional novel deleterious mutation in TH (c.43C>T) and EVC2 (c.2614C>T) genes.
UNASSIGNED: It is concluded that in addition to novel mutations in MYO7A, TH and EVC2, the CDH23 and GJB2 can also be responsible for deafness in the family with consanguineous marriages.

Ellis-van Creveld (EvC) syndrome is an autosomal recessive chondrodysplastic disorder. Affected patients present a wide spectrum of symptoms including short stature, postaxial polydactyly, and dental abnormalities. We previously disrupted Evc2, one of the causative genes for EvC syndrome, in mice using a neural crest-specific, Cre-mediated approach (i.e., P0-Cre, referred to as Evc2 P0 mutants). Despite the fact that P0-Cre predominantly targets the mid-facial region, we reported that many mid-facial defects identified in Evc2 global mutants are not present in Evc2 P0 mutants at postnatal day 8 (P8). In the current study, we used multiple Cre lines (P0-Cre and Wnt1-Cre, respectively), to specifically delete Evc2 in neural crest-derived tissues and compared the resulting mid-facial defects at multiple time points (P8 and P28, respectively). While both Cre lines indistinguishably targeted the mid-facial region, they differentially targeted the anterior portion of the skull base. By comprehensively analyzing the shapes of conditional mutant skulls, we detected differentially affected mid-facial defects in Evc2 P0 mutants and Evc2 Wnt1 mutants. Micro-CT analysis of the skull base further revealed that the Evc2 mutation leads to a differentially affected skull base, caused by premature closure of the intersphenoid synchondrosis (presphenoidal synchondrosis), which limited the elongation of the anterior skull base during the postnatal development of the skull. Given the importance of the skull base in mid-facial bone development, our results suggest that loss of function of Evc2 within the skull base secondarily leads to many aspects of the mid-facial defects developed by the EvC syndrome.

Multilocus analysis of rare or genetically heterogeneous diseases is a distinct advantage of next-generation sequencing (NGS) over conventional single-gene investigations. Recent studies have begun to uncover an under-recognized prevalence of dual molecular diagnoses in patients with a \"blended\" phenotype that is the result of 2 clinical diagnoses involving 2 separate genetic loci. This blended phenotype could be mistakenly interpreted as a novel clinical extension of a single-gene disorder. In this study, we ascertained a proband from a large consanguineous Iranian family who manifests postlingual, progressive, moderate hearing loss in addition to suspected Ellis-van Creveld syndrome phenotype. NGS with a customized skeletal dysplasia panel containing over 370 genes and subsequent bioinformatics analysis disclosed 2 homozygous mutations in EVC2 (c.2653C>T; p.Arg885*) and COL11A2 (c.966dup; p.Thr323Hisfs*19), respectively. This study highlights a dual molecular diagnosis in a patient with a blending of 2 distinct phenotypes and illustrates the advantage and importance of this staple technology to facilitate rapid and comprehensive genetic dissection of a heterogeneous phenotype. The differentiation between phenotypic expansion of a genetic disorder and a blended phenotype that is due to more than one distinct genetic aberration is essential in order to reduce the diagnostic odyssey endured by patients.

EvC syndrome is a type of autosomal-recessive chondrodysplasia. Previous case studies in patients suggest abnormal craniofacial development, in addition to dwarfism and tooth abnormalities. To investigate how craniofacial development is affected in EvC patients, surface models were generated from micro-CT scans of control mice, Evc2 global mutant mice and Evc2 neural crest-specific mutant mice. The anatomic landmarks were placed on the surface model to assess the morphological abnormalities in the Evc2 mutants. Through analyzing the linear and angular measurements between landmarks, we identified a smaller overall skull, shorter nasal bone, shorter frontal bone, and shorter cranial base in the Evc2 global mutants. By comparing neural crest-specific Evc2 mutants with control mice, we demonstrated that the abnormalities within the mid-facial regions are not accounted for by the Evc2 mutation within these regions. Additionally, we also identified disproportionate length to width ratios in the Evc2 mutants at all levels from anterior to posterior of the skull. Overall, this study demonstrates a more comprehensive analysis on the craniofacial morphological abnormalities in EvC syndrome and provides the developmental insight to appreciate the impact of Evc2 mutation within the neural crest cells on multiple aspects of skull deformities. Anat Rec, 2017. © 2017 Wiley Periodicals, Inc. Anat Rec, 301:46-55, 2018. © 2017 Wiley Periodicals, Inc.