FBLN2 is associated with Goldenhar syndrome and is essential for cranial neural crest cell development.

Goldenhar syndrome, a rare craniofacial malformation, is characterized by developmental anomalies in the first and second pharyngeal arches. Its etiology is considered to be heterogenous, including both genetic and environmental factors that remain largely unknown. To further elucidate the genetic cause in a five-generation Goldenhar syndrome pedigree and exploit the whole-exome sequencing (WES) data of this pedigree, we generated collapsed haplotype pattern markers based on WES and employed rare variant nonparametric linkage analysis. FBLN2 was identified as a candidate gene via analysis of WES data across the significant linkage region. A fbln2 knockout zebrafish line was established by CRISPR/Cas9 to examine the gene's role in craniofacial cartilage development. fbln2 was expressed specifically in the mandible during the zebrafish early development, while fbln2 knockout zebrafish exhibited craniofacial malformations with abnormal chondrocyte morphologies. Functional studies revealed that fbln2 knockout caused abnormal chondrogenic differentiation, apoptosis, and proliferation of cranial neural crest cells (CNCCs), and downregulated the bone morphogenic protein (BMP) signaling pathway in the zebrafish model. This study demonstrates the role of FBLN2 in CNCC development and BMP pathway regulation, and highlights FBLN2 as a candidate gene for Goldenhar syndrome, which may have implications for the selection of potential screening targets and the development of treatments for conditions like microtia-atresia.

A recurrent missense variant in EYA3 gene is associated with oculo-auriculo-vertebral spectrum.

Goldenhar syndrome or oculo-auriculo-vertebral spectrum (OAVS) is a complex developmental disorder characterized by asymmetric ear anomalies, hemifacial microsomia, ocular and vertebral defects. We aimed at identifying and characterizing a new gene associated with OAVS. Two affected brothers with OAVS were analyzed by exome sequencing that revealed a missense variant (p.(Asn358Ser)) in the EYA3 gene. EYA3 screening was then performed in 122 OAVS patients that identified the same variant in one individual from an unrelated family. Segregation assessment in both families showed incomplete penetrance and variable expressivity. We investigated this variant in cellular models to determine its pathogenicity and demonstrated an increased half-life of the mutated protein without impact on its ability to dephosphorylate H2AFX following DNA repair pathway induction. Proteomics performed on this cellular model revealed four significantly predicted upstream regulators which are PPARGC1B, YAP1, NFE2L2 and MYC. Moreover, eya3 knocked-down zebrafish embryos developed specific craniofacial abnormalities corroborating previous animal models and supporting its involvement in the OAVS. Additionally, EYA3 gene expression was deregulated in vitro by retinoic acid exposure. EYA3 is the second recurrent gene identified to be associated with OAVS. Moreover, based on protein interactions and related diseases, we suggest the DNA repair as a key molecular pathway involved in craniofacial development.

Functional and genetic analyses of ZYG11B provide evidences for its involvement in OAVS.

BACKGROUND: The Oculo-Auriculo-Vertebral Spectrum (OAVS) or Goldenhar Syndrome is an embryonic developmental disorder characterized by hemifacial microsomia associated with auricular, ocular and vertebral malformations. The clinical heterogeneity of this spectrum and its incomplete penetrance limited the molecular diagnosis. In this study, we describe a novel causative gene, ZYG11B. METHODS: A sporadic case of OAVS was analyzed by whole exome sequencing in trio strategy. The identified candidate gene, ZYG11B, was screened in 143 patients by next generation sequencing. Overexpression and immunofluorescence of wild-type and mutated ZYG11B forms were performed in Hela cells. Moreover, morpholinos were used for transient knockdown of its homologue in zebrafish embryo. RESULTS: A nonsense de novo heterozygous variant in ZYG11B, (NM_024646, c.1609G>T, p.Glu537*) was identified in a single OAVS patient. This variant leads in vitro to a truncated protein whose subcellular localization is altered. Transient knockdown of the zebrafish homologue gene confirmed its role in craniofacial cartilages architecture and in notochord development. Moreover, ZYG11B expression regulates a cartilage master regulator, SOX6, and is regulated by Retinoic Acid, a known developmental toxic molecule leading to clinical features of OAVS. CONCLUSION: Based on genetic, cellular and animal model data, we proposed ZYG11B as a novel rare causative gene for OAVS.

A microanatomic abnormality of the lacrimal gland associated with Goldenhar syndrome.

A 12-month-old male infant, noted from birth to have a diffuse right temporal epibulbar thickening that encroached on the limbus inferotemporally, was found to manifest stigmata of Goldenhar syndrome, including a limbal dermoid with vellus hairs, esotropia, astigmatism, fullness and ectropion of the lower eyelid, preauricular skin tag, agenesis of the right kidney, and a supernumerary rib. In the excised epibulbar specimen, in addition to a solid dermoid, lobules of lacrimal gland tissue were interpreted as a portion of the palpebral or orbital lobes. This tissue displayed a unique histopathologic finding. Within some of the lobules were cuffs of eosinophilic squamous (epidermoid) cells that surrounded the intralobular ductules and made variable incursions into, with replacement of, the acinar units. Immunohistochemistry disclosed that the normal acinar and lumen-forming ductular cells were intermediate weight cytokeratin7-positive. The acinar cells were additionally gross cystic disease fluid protein-15 positive. The cells of the squamous cuffs were heavy weight cytokeratin 5/6-positive. The outermost basal cells of the cuffs were cytokeratin 14-positive, in common with the myoepithelial cells of the acini. The intraacinar squamous cells were negative for smooth muscle actin and gross cystic disease fluid protein-15. These findings suggest, but do not prove, that the source of the periductular and acinar squamous metaplasia was the germinal transitional cells where the acinar myoepithelium interfaces and imperceptibly converts into ductular basal cells. The foregoing findings are evaluated in the context of the panoply of ocular, facial, and visceral anomalies manifested in Goldenhar spectrum.

Manejo anestésico y de la vía aérea en un niño con síndrome de Goldenhar / Management of anaesthesia and the airway in a child with Goldenhar syndrome

No disponible