Hearing loss in peripheral facial palsy after decompression surgery

Facial paralysis can result from a variety of etiologies; the most common is the idiopathic type. Evaluation and treatment are particularly complex. The treatment of acute facial paralysis may require facial nerve decompression surgery. Any structure near the path of the facial nerve is at risk during transmastoid decompression surgery. AIM: This is a retrospective study, carried out in order to evaluate hearing loss after transmastoid decompression and how idiopathic cases evolved in terms of their degree of paralysis in the last 15 years. MATERIALS AND METHODS: We selected the charts from 33 patients submitted to transmastoid facial nerve decompression in the past 15 years and we assessed their hearing loss and facial paralysis. RESULTS: There was a high percentage (61%) of patients with some degree of hearing loss after the procedure and in all cases there was improvement in the paralysis. DISCUSSION: The values obtained are similar to those reported in the literature. One possible explanation for this hearing loss is the vibration transmission by drilling near the ossicular chain. CONCLUSION: The surgical procedure is not risk free; indications, risks and benefits should be explained to patients through an informed consent form.A paralisia facial pode resultar de uma variedade de etiologias, sendo a mais comum a idiopática. A avaliação e o tratamento são particularmente complexos. O tratamento da paralisia facial aguda pode envolver cirurgia de descompressão do nervo facial. Qualquer estrutura perto do trajeto do nervo facial está em risco durante a cirurgia de descompressão via transmastoidea. OBJETIVO: Estudo retrospectivo que irá avaliar a perda auditiva após descompressão via transmastoidea e a evolução do grau de paralisia nos casos idiopáticos dos últimos 15 anos. MATERIAL E MÉTODO: Foram selecionados prontuários de 33 pacientes submetidos à descompressão do nervo facial via transmastoidea nos últimos 15 anos e avaliou-se a perda auditiva e a paralisia facial. RESULTADOS: Observou-se alta porcentagem (61%) dos pacientes com algum grau de perda auditiva após o procedimento e, em todos os casos, houve melhora da paralisia. CONCLUSÃO: O procedimento cirúrgico não é isento de riscos. Indicações, riscos e benefícios devem ser esclarecidos aos pacientes por meio de consentimento informado.UNIFESP-EPMUNIFESP-EPM Setor de OtologiaUNIFESP, EPM, Setor de OtologiaSciEL

A Novel null homozygous mutation confirms <i>CACNA2D2</i> as a gene mutated in epileptic encephalopathy

Contribution to epileptic encephalopathy (EE) of mutations in CACNA2D2, encoding α2δ-2 subunit of Voltage Dependent Calcium Channels, is unclear. To date only one CACNA2D2 mutation altering channel functionality has been identified in a single family. In the same family, a rare CELSR3 polymorphism also segregated with disease. Involvement of CACNA2D2 in EE is therefore not confirmed, while that of CELSR3 is questionable. In a patient with epilepsy, dyskinesia, cerebellar atrophy, psychomotor delay and dysmorphic features, offspring to consanguineous parents, we performed whole exome sequencing (WES) for homozygosity mapping and mutation detection. WES identified extended autozygosity on chromosome 3, containing two novel homozygous candidate mutations: c.1295delA (p.Asn432fs) in CACNA2D2 and c.G6407A (p.Gly2136Asp) in CELSR3. Gene prioritization pointed to CACNA2D2 as the most prominent candidate gene. The WES finding in CACNA2D2 resulted to be statistically significant (p = 0.032), unlike that in CELSR3. CACNA2D2 homozygous c.1295delA essentially abolished α2δ-2 expression. In summary, we identified a novel null CACNA2D2 mutation associated to a clinical phenotype strikingly similar to the Cacna2d2 null mouse model. Molecular and statistical analyses together argued in favor of a causal contribution of CACNA2D2 mutations to EE, while suggested that finding in CELSR3, although potentially damaging, is likely incidental

Missense PDSS1 mutations in CoenzymeQ10 synthesis cause optic atrophy and sensorineural deafness

CoenzymeQ10 is one of the main cellular antioxidants and an essential lipid involved in numerous cell reactions, such as energy production and apoptosis modulation. A large number of enzymes are involved in CoQ10 biosynthesis. Mutations in the genes encoding for these enzymes cause a CoQ10 deficiency, characterized by neurological and systemic symptoms. Here we describe two young sisters with sensorineural deafness followed by optic atrophy, due to a novel homozygous pathogenic variant in PDSS1. The visual system seems to be mainly involved when the first steps of CoQ10 synthesis are impaired (PDSS1, PDSS2, and COQ2 deficiency)

The RNA-binding protein FUS/TLS interacts with SPO11 and PRDM9 and localize at meiotic recombination hotspots

: In mammals, meiotic recombination is initiated by the introduction of DNA double strand breaks (DSBs) into narrow segments of the genome, defined as hotspots, which is carried out by the SPO11/TOPOVIBL complex. A major player in the specification of hotspots is PRDM9, a histone methyltransferase that, following sequence-specific DNA binding, generates trimethylation on lysine 4 (H3K4me3) and lysine 36 (H3K36me3) of histone H3, thus defining the hotspots. PRDM9 activity is key to successful meiosis, since in its absence DSBs are redirected to functional sites and synapsis between homologous chromosomes fails. One protein factor recently implicated in guiding PRDM9 activity at hotspots is EWS, a member of the FET family of proteins that also includes TAF15 and FUS/TLS. Here, we demonstrate that FUS/TLS partially colocalizes with PRDM9 on the meiotic chromosome axes, marked by the synaptonemal complex component SYCP3, and physically interacts with PRDM9. Furthermore, we show that FUS/TLS also interacts with REC114, one of the axis-bound SPO11-auxiliary factors essential for DSB formation. This finding suggests that FUS/TLS is a component of the protein complex that promotes the initiation of meiotic recombination. Accordingly, we document that FUS/TLS coimmunoprecipitates with SPO11 in vitro and in vivo. The interaction occurs with both SPO11β and SPO11α splice isoforms, which are believed to play distinct functions in the formation of DSBs in autosomes and male sex chromosomes, respectively. Finally, using chromatin immunoprecipitation experiments, we show that FUS/TLS is localized at H3K4me3-marked hotspots in autosomes and in the pseudo-autosomal region, the site of genetic exchange between the XY chromosomes

Characterization and identification of hidden rare variants in the human genome

BackgroundBy examining the genotype calls generated by the 1000 Genomes Project we discovered that the human reference genome GRCh37 contains almost 20,000 loci in which the reference allele has never been observed in healthy individuals and around 70,000 loci in which it has been observed only in the heterozygous state.ResultsWe show that a large fraction of this rare reference allele (RRA) loci belongs to coding, functional and regulatory elements of the genome and could be linked to rare Mendelian disorders as well as cancer. We also demonstrate that classical germline and somatic variant calling tools are not capable to recognize the rare allele when present in these loci. To overcome such limitations, we developed a novel tool, named RAREVATOR, that is able to identify and call the rare allele in these genomic positions. By using a small cancer dataset we compared our tool with two state-of-the-art callers and we found that RAREVATOR identified more than 1,500 germline and 22 somatic RRA variants missed by the two methods and which belong to significantly mutated pathways.ConclusionsThese results show that, to date, the investigation of around 100,000 loci of the human genome has been missed by re-sequencing experiments based on the GRCh37 assembly and that our tool can fill the gap left by other methods. Moreover, the investigation of the latest version of the human reference genome, GRCh38, showed that although the GRC corrected almost all insertions and a small part of SNVs and deletions, a large number of functionally relevant RRAs still remain unchanged. For this reason, also future resequencing experiments, based on GRCh38, will benefit from RAREVATOR analysis results. RAREVATOR is freely available at http://sourceforge.net/projects/rarevator

The relevance of mitochondrial DNA variants fluctuation during reprogramming and neuronal differentiation of human iPSCs

The generation of inducible pluripotent stem cells (iPSCs) is a revolutionary technique allowing production of pluripotent patient-specific cell lines used for disease modeling, drug screening, and cell therapy. Integrity of nuclear DNA (nDNA) is mandatory to allow iPSCs utilization, while quality control of mitochondrial DNA (mtDNA) is rarely included in the iPSCs validation process. In this study, we performed mtDNA deep sequencing during the transition from parental fibroblasts to reprogrammed iPSC and to differentiated neuronal precursor cells (NPCs) obtained from controls and patients affected by mitochondrial disorders. At each step, mtDNA variants, including those potentially pathogenic, fluctuate between emerging and disappearing, and some having functional implications. We strongly recommend including mtDNA analysis as an unavoidable assay to obtain fully certified usable iPSCs and NPCs.Peer reviewe

Loss of function mutations in CCDC32 cause a congenital syndrome characterized by craniofacial, cardiac and neurodevelopmental anomalies

Despite the wide use of genomics to investigate the molecular basis of rare congenital malformations, a significant fraction of patients remains bereft of diagnosis. As part of our continuous effort to recruit and perform genomic and functional studies on such cohorts, we investigated the genetic and mechanistic cause of disease in two independent consanguineous families affected by overlapping craniofacial, cardiac, laterality, and neurodevelopmental anomalies. Using whole exome sequencing, we identified homozygous frameshift CCDC32 variants in three affected individuals. Functional analysis in a zebrafish model revealed that ccdc32 depletion recapitulates the human phenotypes. Because some of the patient phenotypes overlap defects common to ciliopathies, we asked if loss of CCDC32 might contribute to the dysfunction of this organelle. Consistent with this hypothesis, we show that ccdc32 is required for normal cilia formation in zebrafish embryos and mammalian cell culture, arguing that ciliary defects are at least partially involved in the pathomechanism of this disorder

Il Paleolitico nei monti della Tolfa: nuove ricerche e prospettive future

International audienc

Saccharomyces cerevisiae as a model to study the role of mutations in SDHA gene associated to hereditary optic neuropathies

Hereditary optic neuropathies (HON) are genetic diseases which lead to the loss of central vision and it has been estimated that in Europe they affect more than 50.000 people. HON are characterized by selective loss of retinal ganglion cells (RGCs), leading to optic nerve atrophy and different degrees of visual impairment and blindness. Thanks to next generation sequencing, three heterozygous mutations in SDHA gene were identified in patients, that could be associated with these pathologies. SDHA encodes for one of the four subunits of the succinate dehydrogenase complex, involved in both the Krebs cycle and the mitochondrial electron transport chain. To evaluate whether these mutations are the specific cause of the pathology, it was necessary to validate them. The yeast Saccharomyces cerevisiae is extensively used to prove with high confidence the link between novel mutations and mitochondrial diseases, since yeast can survive without mitochondrial DNA or with large deletions of it, and can grow on fermentable carbon sources in absence of an oxidative metabolism. Besides, several human genes encoding for mitochondrial proteins are present and often conserved in yeast, giving the chance to introduce the mutation in the yeast orthologous gene or to introduce the human pathological allele in a strain disrupted in its orthologue. SDHA and SDH1, its yeast orthologue, encodes for proteins which share more than 60% of identity, and the three variants found in patients affect amino acids which are conserved in most organisms, including fungi and mammals. The three mutations were introduced in SDH1, and these mutant alleles were inserted in a SDH1-disrupted strain. Our results showed that the presence of mutant alleles leads to a decrease of the oxidative growth and of the oxygen consumption rate compared to the strain harboring SDH1 wild type allele. Furthermore, a strong depletion in the succinate dehydrogenase activity was also observed. Western blots showed that the steady state levels of the mutant proteins were similar or slightly reduced compared to the levels of wild type Sdh1, whereas Sdh2, the second subunit of the complex which interacts directly with Sdh1, is absent or strongly decreased. These results suggest that the substitutions in Sdh1/SDHA are pathological and that affects the stability of the complex. Besides, through the construction of heterozygous diploid strains, we demonstrated that two of three mutations are dominant negative, thus explaining the observation that the patients are heterozygous for each of these mutations