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OtoRhinoLaryngology by Sfakianakis G.Alexandros Sfakianakis G.Alexandros,Anapafseos 5 Agios Nikolaos 72100 Crete Greece,tel : 00302841026182,00306932607174
Mutations in TUBB4B Cause a Distinctive Sensorineural Disease.
Am J Hum Genet. 2017 Nov 22;:
Authors: Luscan R, Mechaussier S, Paul A, Tian G, Gérard X, Defoort-Dellhemmes S, Loundon N, Audo I, Bonnin S, LeGargasson JF, Dumont J, Goudin N, Garfa-Traoré M, Bras M, Pouliet A, Bessières B, Boddaert N, Sahel JA, Lyonnet S, Kaplan J, Cowan NJ, Rozet JM, Marlin S, Perrault I
Abstract
Leber congenital amaurosis (LCA) is a neurodegenerative disease of photoreceptor cells that causes blindness within the first year of life. It occasionally occurs in syndromic metabolic diseases and plurisystemic ciliopathies. Using exome sequencing in a multiplex family and three simplex case subjects with an atypical association of LCA with early-onset hearing loss, we identified two heterozygous mutations affecting Arg391 in β-tubulin 4B isotype-encoding (TUBB4B). Inspection of the atomic structure of the microtubule (MT) protofilament reveals that the β-tubulin Arg391 residue contributes to a binding pocket that interacts with α-tubulin contained in the longitudinally adjacent αβ-heterodimer, consistent with a role in maintaining MT stability. Functional analysis in cultured cells overexpressing FLAG-tagged wild-type or mutant TUBB4B as well as in primary skin-derived fibroblasts showed that the mutant TUBB4B is able to fold, form αβ-heterodimers, and co-assemble into the endogenous MT lattice. However, the dynamics of growing MTs were consistently altered, showing that the mutations have a significant dampening impact on normal MT growth. Our findings provide a link between sensorineural disease and anomalies in MT behavior and describe a syndromic LCA unrelated to ciliary dysfunction.
PMID: 29198720 [PubMed - as supplied by publisher]
Whole exome sequencing identifies TRIOBP pathogenic variants as a cause of post-lingual bilateral moderate-to-severe sensorineural hearing loss.
BMC Med Genet. 2017 Dec 02;18(1):142
Authors: Pollak A, Lechowicz U, Murcia Pieńkowski VA, Stawiński P, Kosińska J, Skarżyński H, Ołdak M, Płoski R
Abstract
BACKGROUND: Implementation of whole exome sequencing has provided unique opportunity for a wide screening of causative variants in genetically heterogeneous diseases, including nonsyndromic hearing impairment. TRIOBP in the inner ear is responsible for proper structure and function of stereocilia and is necessary for sound transduction.
METHODS: Whole exome sequencing followed by Sanger sequencing was conducted on patients derived from Polish hearing loss family.
RESULTS: Based on whole exome analysis, we identified two TRIOBP pathogenic variants (c.802_805delCAGG, p.Gln268Leufs*610 and c.5014G>T, p.Gly1672*, the first of which was novel) causative of nonsyndromic, peri- to postlingual, moderate-to-severe hearing loss in three siblings from a Polish family. Typically, TRIOBP pathogenic variants lead to prelingual, severe-to-profound hearing loss, thus the onset and degree of hearing impairment in our patients represent a distinct phenotypic manifestation caused by TRIOBP variants. The pathogenic variant p.Gln268Leufs*610 disrupts the TRIOBP-4 and TRIOBP-5 isoforms (both expressed exclusively in the inner ear and retina) whereas the second pathogenic variant c.514G>T, p.Gly1672* affects only TRIOBP-5.
CONCLUSIONS: The onset and degree of hearing impairment, characteristic for our patients, represent a unique phenotypic manifestation caused by TRIOBP pathogenic variants. Although TRIOBP alterations are not a frequent cause of hearing impairment, this gene should be thoroughly analyzed especially in patients with a postlingual hearing loss. A delayed onset of hearing impairment due to TRIOBP pathogenic variants creates a potential therapeutic window for future targeted therapies.
PMID: 29197352 [PubMed - in process]
Related Articles |
Chronic Infantile Neurological Cutaneous and Articular (CINCA) syndrome: a review.
Orphanet J Rare Dis. 2016 12 07;11(1):167
Authors: Finetti M, Omenetti A, Federici S, Caorsi R, Gattorno M
Abstract
INTRODUCTION: The Chronic Infantile Neurological Cutaneous and Articular (CINCA, or Neonatal-onset multisystem inflammatory disease NOMID) is a rare autoinflammatory disease identified in 1987 by Prieur et al., typically characterized by the triad of skin rash, arthropathy and central nervous system manifestations. It represents the most severe phenotype of the cryopyrin-associated periodic syndrome (CAPS).
CLINICAL DESCRIPTION AND ETIOLOGY: The syndrome is due to autosomal dominant gain of function mutations in NLRP3, which encodes a key component of the innate immunity that regulates the activation and secretion of interleukin (IL)-1β. From the first days of life, patients display an urticarial rash in association with chronic inflammation with a typical facies featured by frontal bossing and saddle back nose. The CNS manifestations include chronic aseptic meningitis leading to brain atrophy, mental delay and sensorineural hearing loss. Chronic polyarthritis and alteration of the growth cartilage also may be present. CINCA/NOMID diagnosis is made clinically, based on the presence of characteristic features. The detection of NLRP3 mutations is diagnostic in 65-70% of cases. Indeed, up to 40% of affected patients are negative for germline NLRP3 mutations and several subjects are carriers of somatic mosaicism. Due to the pivotal role of Cryopyrin in the control of Caspase-1 activation and the massive secretion of active IL-1β observed in cryopyrin-mutated individuals, anti-IL1 treatment represents the standard therapy.
CONCLUSION: Prognosis of CINCA/NOMID syndrome has been changed by the availability of anti-IL1 drugs. Nowadays, the use of anti-IL-1 drugs has sensibly reduced the risk of developing main complications such as severe intellectual disability, hearing-loss and amyloidosis, if treatment is started early on.
PMID: 27927236 [PubMed - indexed for MEDLINE]