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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. [ABSTRACT FROM AUTHOR]

Background: OFD1 syndrome is a rare ciliopathy inherited on a dominant X-linked mode, typically lethal in males in the first or second trimester of pregnancy. It is characterized by oral cavity and digital anomalies possibly associated with cerebral and renal signs. Its prevalence is between 1/250,000 and 1/50,000 births. It is due to heterozygous mutations of OFD1 and mutations are often de novo (75%). Familial forms show highly variable phenotypic expression. OFD1 encodes a protein involved in centriole growth, distal appendix formation, and ciliogenesis. Cases: We report the investigation of three female fetuses in which corpus callosum agenesis was detected by ultrasound during the second trimester of pregnancy. In all three fetuses, fetopathological examination allowed the diagnosis of OFD1 syndrome, which was confirmed by molecular analysis. Conclusions: To our knowledge, these are the first case reports of antenatal diagnosis of OFD1 syndrome in the absence of familial history, revealed following detection of agenesis of the corpus callosum. They highlight the impact of fetal examination following termination of pregnancy for brain malformations. They also highlight the contribution of ciliary genes to corpus callosum development. [ABSTRACT FROM AUTHOR]

Background Oculo-auriculo-vertebral spectrum (OAVS) is a developmental disorder involving first and second branchial arches derivatives, mainly characterised by asymmetric ear anomalies, hemifacial microsomia, ocular defects and vertebral malformations. Although numerous chromosomal abnormalities have been associated with OAVS, no causative gene has been identified so far. Objectives We aimed to identify the first causative gene for OAVS. Methods As sporadic cases are mostly described in Goldenhar syndrome, we have performed whole exome sequencing (WES) on selected affected individuals and their unaffected parents, looking for de novo mutations. Candidate gene was tested through transient knockdown experiment in zebrafish using a morpholino-based approach. A functional test was developed in cell culture in order to assess deleterious consequences of mutations. Results By WES, we identified a heterozygous nonsense mutation in one patient in the myelin transcription factor 1 (MYT1) gene. Further, we detected one heterozygous missense mutation in another patient among a cohort of 169 patients with OAVS. This gene encodes the MYT1. Functional studies by transient knockdown of myt1a, homologue of MYT1 in zebrafish, led to specific craniofacial cartilage alterations. Treatment with all-trans retinoic acid (RA), a known teratogenic agent causing OAVS, led to an upregulation of cellular endogenous MYT1 expression. Additionally, cellular wild-type MYT1 overexpression induced a downregulation of RA receptor ß (RARB), whereas mutated MYT1 did not. Conclusion We report MYT1 as the first gene implicated in OAVS, within the RA signalling pathway. [ABSTRACT FROM AUTHOR]

Cilia have a unique diffusion barrier (“gate”) within their proximal region, termed transition zone (TZ), that compartmentalises signalling proteins within the organelle. The TZ is known to harbour two functional modules/complexes (Meckel syndrome [MKS] and Nephronophthisis [NPHP]) defined by genetic interaction, interdependent protein localisation (hierarchy), and proteomic studies. However, the composition and molecular organisation of these modules and their links to human ciliary disease are not completely understood. Here, we reveal Caenorhabditis elegans CEP-290 (mammalian Cep290/Mks4/Nphp6 orthologue) as a central assembly factor that is specific for established MKS module components and depends on the coiled coil region of MKS-5 (Rpgrip1L/Rpgrip1) for TZ localisation. Consistent with a critical role in ciliary gate function, CEP-290 prevents inappropriate entry of membrane-associated proteins into cilia and keeps ARL-13 (Arl13b) from leaking out of cilia via the TZ. We identify a novel MKS module component, TMEM-218 (Tmem218), that requires CEP-290 and other MKS module components for TZ localisation and functions together with the NPHP module to facilitate ciliogenesis. We show that TZ localisation of TMEM-138 (Tmem138) and CDKL-1 (Cdkl1/Cdkl2/Cdkl3/Cdlk4 related), not previously linked to a specific TZ module, similarly depends on CEP-290; surprisingly, neither TMEM-138 or CDKL-1 exhibit interdependent localisation or genetic interactions with core MKS or NPHP module components, suggesting they are part of a distinct, CEP-290-associated module. Lastly, we show that families presenting with Oral-Facial-Digital syndrome type 6 (OFD6) have likely pathogenic mutations in CEP-290-dependent TZ proteins, namely Tmem17, Tmem138, and Tmem231. Notably, patient fibroblasts harbouring mutated Tmem17, a protein not yet ciliopathy-associated, display ciliogenesis defects. Together, our findings expand the repertoire of MKS module-associated proteins—including the previously uncharacterised mammalian Tmem80—and suggest an MKS-5 and CEP-290-dependent assembly pathway for building a functional TZ. [ABSTRACT FROM AUTHOR]

Centrioles are microtubule-based, barrel-shaped structures that initiate the assembly of centrosomes and cilia. How centriole length is precisely set remains elusive. The microcephaly protein CPAP (also known as MCPH6) promotes procentriole growth, whereas the oral-facial-digital (OFD) syndrome protein OFD1 represses centriole elongation. Here we uncover a new subtype of OFD with severe microcephaly and cerebral malformations and identify distinct mutations in two affected families in the evolutionarily conserved C2CD3 gene. Concordant with the clinical overlap, C2CD3 colocalizes with OFD1 at the distal end of centrioles, and C2CD3 physically associates with OFD1. However, whereas OFD1 deletion leads to centriole hyperelongation, loss of C2CD3 results in short centrioles without subdistal and distal appendages. Because C2CD3 overexpression triggers centriole hyperelongation and OFD1 antagonizes this activity, we propose that C2CD3 directly promotes centriole elongation and that OFD1 acts as a negative regulator of C2CD3. Our results identify regulation of centriole length as an emerging pathogenic mechanism in ciliopathies. [ABSTRACT FROM AUTHOR]

The promoter of the cystic fibrosis transmembrane conductance regulator gene CFTR is tightly controlled by regulators including CCAAT/enhancer binding proteins (C/EBPs). We previously reported that the transcription factors YY1 and USF2 affect CFTR expression. We can now demonstrate that C/EBPβ, a member of the CCAAT family, binds to the CFTR promoter and contributes to its transcriptional activity. Our data reveal that C/EBPβ cooperates with USF2 and acts antagonistically to YY1 in the control of CFTR expression. Interestingly, YY1, a strong repressor, fails to repress the CFTR activation induced by USF2 through DNA binding competition. Collectively, the data strongly suggest a model by which USF2 functionally interacts with YY1 blocking its inhibitory activity, in favour of C/EBPβ transactivation. Further investigation into the interactions between these three proteins revealed that phosphorylation of C/EBPβ influences the DNA occupancy of YY1 and favours the interaction between USF2 and YY1. This phosphorylation process has several implications in the CFTR transcriptional process, thus evoking an additional layer of complexity to the mechanisms influencing CFTR gene regulation. [ABSTRACT FROM AUTHOR]

A large number of 5-HT receptors (>15) have been identified by molecular cloning technology over the past 10 years. This review briefly summarizes available information regarding the functional and therapeutic implications of serotonin receptor diversity for neurology and psychiatry. 5-HT receptors are divided into seven main families: 5-HT1, 5-HT2, 5-HT3, 5-HT4, 5-HT5, 5-HT6, and 5-HT7. Several families (e.g., 5-HT1 family) have many members (e.g., 5-HT1A, 5-HT1B, 5-HT1D, 5-HT1E, 5-HT1F), each of which is encoded by a distinct gene product. In addition to the genomic diversity of 5-HT receptors, splice variants and editing isoforms exist for many of the 5-HT receptors, making the family even more diverse. Evidence that is summarized in this review suggests that 5-HT receptors represent novel therapeutic targets for a number of neurologic and psychiatric diseases including migraine headaches, chronic pain conditions, schizophrenia, anxiety, depression, eating disorders, obsessive compulsive disorder, pervasive developmental disorders, and obesity-related conditions (Type II diabetes, hypertension, obesity syndromes). It is possible that subtype-selective serotonergic agents may revolutionize the treatment for a number of medical, psychiatric, and neurological disorders. [ABSTRACT FROM AUTHOR]

Oral-facial-digital syndromes (OFDS) gather rare genetic disorders characterised by facial, oral and digital abnormalities associated with a wide range of additional features (polycystic kidney disease, cerebral malformations and several others) to delineate a growing list of OFDS subtypes. The most frequent, OFD type I, is caused by a heterozygous mutation in the OFD1 gene encoding a centrosomal protein. The wide clinical heterogeneity of OFDS suggests the involvement of other ciliary genes. For 15 years, we have aimed to identify the molecular bases of OFDS. This effort has been greatly helped by the recent development of whole-exome sequencing (WES). Here, we present all our published and unpublished results for WES in 24 cases with OFDS. We identified causal variants in five new genes ( C2CD3 , TMEM107 , INTU , KIAA0753 and IFT57 ) and related the clinical spectrum of four genes in other ciliopathies ( C5orf42 , TMEM138 , TMEM231 and WDPCP ) to OFDS. Mutations were also detected in two genes previously implicated in OFDS. Functional studies revealed the involvement of centriole elongation, transition zone and intraflagellar transport defects in OFDS, thus characterising three ciliary protein modules: the complex KIAA0753-FOPNL-OFD1, a regulator of centriole elongation; the Meckel-Gruber syndrome module, a major component of the transition zone; and the CPLANE complex necessary for IFT-A assembly. OFDS now appear to be a distinct subgroup of ciliopathies with wide heterogeneity, which makes the initial classification obsolete. A clinical classification restricted to the three frequent/well-delineated subtypes could be proposed, and for patients who do not fit one of these three main subtypes, a further classification could be based on the genotype., Competing Interests: Competing interests: None declared., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

Hereditary factor VII (FVII) deficiency is a rare autosomal recessive disorder. Deleterious mutations that prevent the synthesis of any amount of functional FVII have been associated with life-threatening haemorrhage in neonates. Here we report two infants, of Maghrebian origin, who suffered a fatal spontaneous cerebral haemorrhage. Investigation of the molecular basis for their severe FVII deficiency revealed novel mutations in a homozygous state within the F7 gene promoter: a single nucleotide substitution (c.-65G>C) and a 2bp deletion (c.-60_-59delTT). To determine whether these promoter variants were responsible for the FVII deficiency, computer-assisted sequence analyses were performed. The data predicted a disrupted binding of both HNF4 and COUP-TF transcription factors with each variant. Concordantly, experimental results revealed an altered HNF4-induced transactivation in the promoter mutated variants. The execution of functional tests is critical to ensuring a complete understanding of the effect of any promoter mutant on FVII deficiency. Only then can an accurate molecular diagnosis be made and further genetic counselling and prenatal diagnosis be offered.