Progressive Sensorineural Hearing Loss Research Articles

Natural History of Auditory Function in Patients with Alport Syndrome: A Case Series Study

Background: Alport syndrome (AS) is a genetic disorder characterized by progressive renal disease, ocular abnormalities, and sensorineural hearing loss. However, the audiological profile of patients with AS remains elusive. Thus, this study aims to evaluate the natural history of auditory function in patients with AS. Methods: Exome or targeted sequencing for deafness genes was performed to confirm the pathogenic variants in patients with AS. Results: We identified fifteen individuals with AS who carried pathogenic variants of COL4A3, COL4A4, or COL4A5. Among fifteen, twelve (80%) showed hematuria, and six (40%) showed proteinuria. The patients exhibited bilateral sensorineural hearing loss, which was progressive and symmetric. The hearing thresholds increased according to age and plateaued at the level of 53 dB HL, indicating the hearing loss did not reach the severe-to-moderate level. The auditory dysfunction showed a distinct natural history depending on the inheritance pattern, but there was no remarkable difference between males and females among X-linked AS. Conclusions: Auditory dysfunction in AS is progressive up to the level of moderate hearing loss. Precise auditory rehabilitation for patients with AS is warranted depending on the inheritance pattern and genetic predisposition.

T cell responses and clinical symptoms among infants with congenital cytomegalovirus infection.

BACKGROUNDCongenital cytomegalovirus (cCMV) infection can cause developmental impairment and sensorineural hearing loss (SNHL). To determine the relationship between immune responses to cCMV infection and neurologic sequelae, T cell responses were compared for their connection to clinical symptoms at birth and neurodevelopmental outcomes.METHODSThirty cCMV-infected and 15 uninfected infants were enrolled in a single-center prospective observational case-control study. T cell pp65-specific cytokine responses; CD57, CD28, and PD-1 expression; and memory subsets were compared.RESULTSInfected neonates (73% symptomatic at birth) lacked pp65-specific cytokine-secreting T cells, with elevated frequencies of CD57+, CD28-, and PD-1+CD8+ T cells and effector memory subsets. Though frequencies overlapped between cCMV symptom groups, asymptomatic infants had higher frequencies of CD57+PD-1+CD8+ T cells. Neonates with subsequent developmental delay lacked detectable CMV-specific T cell responses, with patterns resembling those of uninfected infants. Two children with progressive SNHL had high frequencies of PD-1+CD8+ T cells over the first year compared with children without progressive SNHL.CONCLUSIONSimilar to published reports, neonatal viral antigen-specific cytokine-secreting T cell responses were not detected, but overall patterns indicate that globally differentiated memory CD8+ T cell populations were induced by cCMV infection, with higher frequencies of terminally differentiated PD-1+CD8+ T cells potentially associated with asymptomatic infection. In this cohort, a lack of in utero T cell differentiation was associated with developmental delay, and high frequencies of PD-1+CD8+ T cells persisted only in children with progressive SNHL. Further work is needed to define the specificity of these T cells and their mechanistic connection to these outcomes.FUNDINGThis study was funded through an intramural research award at Nationwide Children's Hospital, the Pediatric Infectious Disease Society Fellowship Award funded by Stanley and Susan Plotkin and Sanofi Pasteur, the Abigail Wexner Research Institute at Nationwide Children's Hospital, and the Pichichero Family Foundation Vaccines for Children Initiative Research Award from the Pediatric Infectious Diseases Society Foundation.

Identification and Characterization of Novel Founder Mutations in NDRG1: Refining the Genetic Landscape of Charcot-Marie-Tooth Disease Type 4D in Bulgaria.

Charcot-Marie-Tooth neuropathy type 4D (CMT4D) is a rare genetic disorder of the peripheral nervous system caused by biallelic mutations in the N-Myc Downstream Regulated 1 gene (NDRG1). Patients present with an early onset demyelinating peripheral neuropathy causing severe distal muscle weakness and sensory loss, leading to loss of ambulation and progressive sensorineural hearing loss. The disorder was initially described in the Roma community due to a common founder mutation, and only a handful of disease-causing variants have been described in this gene so far. Here, we present genetic and clinical findings from a large Bulgarian cohort of demyelinating CMT patients harboring recurrent and novel variants in the NDRG1 gene. Notably, two splice-site variants are exclusive to Bulgarian Muslims and reside in ancestral haplotypes, suggesting a founder effect. Functional characterization of these novel variants implicates a loss-of-function mechanism due to shorter gene products. Our findings contribute to a deeper understanding of the genetic and clinical heterogeneity of CMT4D and highlight novel founder mutations in the ethnic minority of Bulgarian Muslims.

A Novel CEP78 Variant Presenting as Cone Dystrophy and Hearing Loss.

Mutations in CEP78 lead to abnormal production of cilia and have previously been identified to cause cone-rod dystrophy (CRD) with progressive sensorineural hearing loss. The authors describe a case of cone dystrophy (CD) with sensorineural hearing loss in a variant that had previously been reported to be of unknown significance and associated with CRD only. This report corroborates the pathogenicity of this variant and highlights that different phenotypes may be associated with one genotype. [Ophthalmic Surg Lasers Imaging Retina 2024;55:XX-XX.].

Long-Term Outcomes of Cochlear Implantation in Usher Syndrome.

Usher syndrome (USH), characterized by bilateral sensorineural hearing loss (SNHL) and retinitis pigmentosa (RP), prompts increased reliance on hearing due to progressive visual deterioration. It can be categorized into three subtypes: USH type 1 (USH1), characterized by severe to profound congenital SNHL, childhood-onset RP, and vestibular areflexia; USH type 2 (USH2), presenting with moderate to severe progressive SNHL and RP onset in the second decade, with or without vestibular dysfunction; and USH type 3 (USH3), featuring variable progressive SNHL beginning in childhood, variable RP onset, and diverse vestibular function. Previous studies evaluating cochlear implant (CI) outcomes in individuals with USH used varying or short follow-up durations, while others did not evaluate outcomes for each subtype separately. This study evaluates long-term CI performance in subjects with USH, at both short-term and long-term, considering each subtype separately. This retrospective, observational cohort study identified 36 CI recipients (53 ears) who were categorized into four different groups: early-implanted USH1 (first CI at ≤7 years of age), late-implanted USH1 (first CI at ≥8 years of age), USH2 and USH3. Phoneme scores at 65 dB SPL with CI were evaluated at 1 year, ≥2 years (mid-term), and ≥5 years postimplantation (long-term). Each subtype was analyzed separately due to the significant variability in phenotype observed among the three subtypes. Early-implanted USH1-subjects (N = 23 ears) achieved excellent long-term phoneme scores (100% [interquartile ranges {IQR} = 95 to 100]), with younger age at implantation significantly correlating with better CI outcomes. Simultaneously implanted subjects had significantly better outcomes than sequentially implanted subjects ( p = 0.028). Late-implanted USH1 subjects (N = 3 ears) used CI solely for sound detection and showed a mean phoneme discrimination score of 12% (IQR = 0 to 12), while still expressing satisfaction with ambient sound detection. In the USH2 group (N = 23 ears), a long-term mean phoneme score of 85% (IQR = 81 to 95) was found. Better outcomes were associated with younger age at implantation and higher preimplantation speech perception scores. USH3-subjects (N = 7 ears) achieved a mean postimplantation phoneme score of 71% (IQR = 45 to 91). This study is currently one of the largest and most comprehensive studies evaluating CI outcomes in individuals with USH, demonstrating that overall, individuals with USH benefit from CI at both short- and long-term follow-up. Due to the considerable variability in phenotype observed among the three subtypes, each subtype was analyzed separately, resulting in smaller sample sizes. For USH1 subjects, optimal CI outcomes are expected with early simultaneous bilateral implantation. Late implantation in USH1 provides signaling function, but achieved speech recognition is insufficient for oral communication. In USH2 and USH3, favorable CI outcomes are expected, especially if individuals exhibit sufficient speech recognition with hearing aids and receive ample auditory stimulation preimplantation. Early implantation is recommended for USH2, given the progressive nature of hearing loss and concomitant severe visual impairment. In comparison with USH2, predicting outcomes in USH3 remains challenging due to the variability found. Counseling for USH2 and USH3 should highlight early implantation benefits and encourage hearing aid use.

Тиамин-зависимая мегалобластная анемия (синдром Роджерса) у ребенка трех лет

Thiamine responsive megaloblastic anemia (TRMA), or Rogers syndrome, is a rare autosomal recessive disease characterized by the development of megaloblastic anemia, diabetes mellitus, and progressive sensorineural hearing loss. In some cases, the syndrome causes ophthalmological disorders (retinitis pigmentosa, optic nerve atrophy, maculopathy, nystagmus), heart diseases (paroxysmal atrial fibrillation, supraventricular tachycardia, congenital heart defects, intracardiac conduction disorders) and neurological disorders (epilepsy, cerebrovascular accidents). TRMA develops due to a mutation in the SLC19A2 gene, which encodes ThTr-1 (thiamine transporter protein) expressed in hematopoietic stem cells, pancreatic beta cells, and inner ear cells. The article presents a clinical case of TRMA in a three-year-old child, with the onset in the first year of life, manifesting as anemia and diabetes mellitus. Thiamine therapy ensured a pronounced positive dynamics: the patient's peripheral blood parameters normalized. The clinical description and the literature review herein aim to raise awareness of doctors of all specialties about this syndrome. An atypical clinical picture and lack of knowledge about TRMA often delay the diagnosis and start of therapy.

Development of CRISPR/Cas9-Based Mouse Models for X-linked Alport Syndrome

Intro: Alport Syndrome (AS) is a rare hereditary disorder characterized by progressive renal impairment and sensorineural hearing loss, resulting from mutations in the genes that encode COL4 synthesis. X-linked Alport Syndrome (XLAS) is the most common form of AS, comprising an estimated 80% of all human AS cases (the others being various forms of autosomal recessive or autosomal dominant AS), and is caused by various mutations on the COL4A5 gene. However, to date, there are no animal models of XLAS. Methods: To facilitate comprehensive preclinical investigations and therapeutic developments, we established two novel mouse models of XLAS using CRISPR/Cas9 technology. Leveraging the robust C57Bl/6J mouse strain, we precisely introduced the L1655R and C1570S mutations, which represent the predominant human variants of XLAS observed in the Western United States. Discussion: Our innovative mouse models not only serve as invaluable tools for elucidating the underlying mechanisms of XLAS pathogenesis but also provide a platform for evaluating the effcacy of potential therapeutic interventions. The establishment of these faithful genetic replicas of human XLAS marks a significant advancement in the field, offering unprecedented opportunities for in-depth mechanistic studies and the development of targeted therapeutic strategies for this debilitating renal and auditory disorder. This research is supported by the National Institutes of Health under Ruth L. Kirschstein National Research Service Award 5T32DK091317 from the National Institute of Diabetes and Digestive and Kidney Diseases and the National Kidney Foundation of Utah and Idaho. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

The impact of amplification on quality of life in women with Turner syndrome

BackgroundIndividuals with Turner syndrome (TS, ORPHA 881) experience barriers in communication throughout life as they navigate both early conductive, and progressive sensorineural hearing loss amid other healthcare needs. Hearing loss is self-identified as one of the largest unmet healthcare needs.PurposeThe purpose of this study was to investigate the impact of treatment for hearing loss on communication confidence and quality of life measures for individuals with TS.Research designWe employed a prospective cross-sectional study design that included both online survey data and audiometric data for a subset of participants.Study sampleWe recruited 179 adults with TS at the Turner Syndrome Society of the United States (TSSUS) Conference, and through a variety of regional TS organizations’ social media platforms. Audiological data was collected onsite at the conference for a subset of 67 participants; 8 of which who were followed after receiving subsequent treatment with hearing aids.Data collection and analysisThe online survey design included demographic questions, the Communication Confidence Profile (CCP), and the RAND 36-Item Health Survey 1.0. Audiometric data included tympanometry, puretone air, and puretone bone conduction thresholds. Descriptive statistics, parametric, and non-parametric tests were used to analyze both survey and audiometric data.Results74% of participants had a self-reported diagnosis of hearing loss, of which 61% were previously recommended amplification. Only 38% of participants reported using hearing aids. For those participants who wore hearing aids, Total CCP Score, ‘Confidence in Ability to Hear Under Various Conditions’, and ‘Energy/Vitality’ metrics were significantly greater than those with untreated hearing loss warranting a hearing aid. Collectively, Total CCP Score and ‘Confidence in Ability to Hear Under Various Conditions’ increased significantly when participants were fit with hearing aids.ConclusionThe results support previous data where hearing loss is a self-identified healthcare concern among women with Turner syndrome, yet many fail to receive appropriate hearing evaluation or treatment. Additionally, the use of hearing aids may improve communication confidence and quality of life in women with Turner syndrome. Furthermore, this study confirms the need for long-term audiological care and monitoring in women with Turner syndrome.

Late-onset, progressive sensorineural hearing loss in the paediatric population: a systematic review.

To review possible risk factors for permanent delayed-onset, progressive sensorineural hearing loss (SNHL) in the paediatric population to recommend follow-up protocols for early detection. PRISMA-compliant systematic review was performed, including observational studies on the paediatric population up to 16years old who have passed the newborn hearing screening programme (NHSP), investigating the development of late-onset, progressive SNHL. Electronic searches were performed through Medline, Embase, Cochrane, and Emcare. 37 studies were included. 21 showed an association between late-onset SNHL and congenital cytomegalovirus (cCMV) infection (age at hearing loss diagnosis 0.75 to 204months, mean 45.6 ± 43.9), while 16 between late-onset SNHL and other congenital or perinatal factors, namely Neonatal Intensive Care Unit (NICU) stay, prematurity, neonatal respiratory failure, mechanical ventilation, extracorporeal membrane oxygenation (ECMO) support, hypocapnia, hypoxia, alkalosis, seizure activity, congenital diaphragmatic hernia (CDH), inner ear malformation, and gene mutations (age at hearing loss diagnosis 2.5 to 156months, mean 38.7 ± 40.7). cCMV infection may cause late-onset SNHL, which can be missed on standard NHSP. There is, therefore, evidence to support universal screening programmes to enable detection in even asymptomatic neonates. Ongoing audiological follow-up for all children with cCMV is advisable, to enable timely treatment. In the paediatric population presenting conditions such as NICU stay > 5days, prematurity ≤ 34weeks gestation, severe neonatal respiratory failure, mechanical ventilation, ECMO support, and CDH surgery, an audiological follow-up from 3months of age up to at least 3-4years of age, and at least annually, should be recommended.

Investigation of a novel TBC1D24 variation causing autosomal dominant non-syndromic hearing loss.

Hearing loss is considered one of the most common sensory neurological defects, with approximately 60% of cases attributed to genetic factors. Human pathogenic variants in the TBC1D24 gene are associated with various clinical phenotypes, including dominant nonsyndromic hearing loss DFNA65, characterized by progressive hearing loss after the development of language. This study provides an in-depth analysis of the causative gene and mutations in a family with hereditary deafness. We recruited a three-generation family with autosomal dominant nonsyndromic hearing loss (ADNSHL) and conducted detailed medical histories and relevant examinations. Next-generation sequencing (NGS) was used to identify genetic variants in the proband, which were then validated using Sanger sequencing. Multiple computational software tools were employed to predict the impact of the variant on the function and structure of the TBC1D24 protein. A series of bioinformatics tools were applied to determine the conservation characteristics of the sequence, establish a three-dimensional structural model, and investigate changes in molecular dynamics. A detailed genotype and phenotype analysis were carried out. The family exhibited autosomal dominant, progressive, postlingual, and nonsyndromic sensorineural hearing loss. A novel heterozygous variant, c.1459C>T (p.His487Tyr), in the TBC1D24 gene was identified and confirmed to be associated with the hearing loss phenotype in this family. Conservation analysis revealed high conservation of the amino acid affected by this variant across different species. The mutant protein showed alterations in thermodynamic stability, elasticity, and conformational dynamics. Molecular dynamics simulations indicated changes in RMSD, RMSF, Rg, and SASA of the mutant structure. We computed the onset age of non-syndromic hearing loss associated with mutations in the TBC1D24 gene and identified variations in the hearing progression time and annual threshold deterioration across different frequencies. The identification of a new variant associated with rare autosomal dominant nonsyndromic hereditary hearing loss in this family broadens the range of mutations in the TBC1D24 gene. This variant has the potential to influence the interaction between the TLDc domain and TBC domain, thereby affecting the protein's biological function.

Альфа-маннозидоз: путь к диагнозу ультраредкого заболевания

Alpha-mannosidosis is a rare autosomal recessive hereditary disease characterized by lysosomal accumulation of olygosaccharides in various tissues due to deficiency of alpha-mannosidase. Low enzyme activity results from homozygous or compound heterozygous mutations of the MAN2B1 gene. Clinical manifestations of alpha-mannosidosis usually develop in childhood or adolescence and include facial deformity (Hurler-like phenotype), mental retardation, progressive sensorineural hearing loss, skeletal abnormalities, neurological and psychiatric disorders, and ocular disease. Demonstration of low activity of acid alpha-mannosidase in dried blood spots and genetic testing can be used for diagnosis. The authors present the case report of alpha-mannosidosis and discuss its pathogenesis, clinical signs and symptoms and approaches to treatment including the long-term enzyme replacement therapy with velmanasa alfa.

Role of Neuroradiological Imaging in Progressive Sensorineural Hearing Loss: A Retrospective Study.

Our aim was to determine prevalence and type of neuro-radiological lesions detected on screening Magnetic Resonance Imaging (MRI) of brain in patients presenting with progressive sensorineural hearing loss in otorhinolaryngology clinic. This retrospective study included 96 screening magnetic resonance imaging MRI brain scans of patients who presented with progressive sensorineural hearing loss in department of otorhinolaryngology. The clinical and radiological data was collected and analysed. Out of 96 screening MRI brain, 19 (19.8%) had positive findings. The commonest imaging finding was presence of vascular loop around facial and vestibulocochlear nerve root complex in 9 cases (9.4%) followed by presence of a cerebellopontine angle lesions in 5 cases (5.2%). The mean age of all patients was 48.5 years and those with positive screening MRI was 40.6 years. A gender gap was noticed with female being 22 (22.9%) in number against 74 (77.1%) males. This is the first retrospective study to determine prevalence and type of neuro-radiological lesions detected on screening magnetic resonance imaging in patients with progressive sensorineural hearing loss. We recommend screening MRI brain in patients with progressive SNHL aged below 60 years and all the described neuroradiological finding provide differential diagnosis. Definition and classification of progressive sensorineural hearing loss should be formulated to standardize the management. Further multi-institutional studies are required to identify social, occupational, genetic, or other factors that can cause gender disparity in patients with progressive SNHL.

Congenital CMV Infection: A Complex Case of Neurological Complications and Therapeutic Approaches in Infancy

Introduction and purpose
 Congenital Cytomegalovirus (CMV) infection stands as the prevalent infection among newborns and it may be associated with later complications such as progressive sensorineural hearing loss or neurological diseases. Infection occurs during pregnancy or during childbirth. Congenital CMV infections manifest in various ways, ranging from asymptomatic cases to severe complications such as microcephaly, hepatosplenomegaly, and chorioretinitis. Routine antibody screenings for pregnant women are not common, underlining the significance of early infection detection to minimize the risks of transmission to the fetus and potential complications in the child.
 The aim of this case report is to present the course of congenital CMV infection and its complication. This case report explores the challenges of managing an infant with congenital CMV infection complicated by hydrocephalus and viral co-infections. The infant underwent various treatments, including antiviral therapy, highlighting the need for multidisciplinary approaches.
 Conclusion
 With no available vaccine, prevention of congenital CMV infection relies on educating reproductive-age women and expectant mothers about infection risks. Early detection, frequent medical check-ups, and preventive education are crucial due to the absence of vaccines. Ongoing exploration of antiviral treatments and prompt interventions is imperative to improve outcomes for infants and families affected by the virus.

Discovery of a Novel Missense Variant in NLRP3 Causing Atypical Cryopyrin-Associated Periodic Syndromes With Hearing Loss as the Primary Presentation, Responsive to Anti-Interleukin-1 Therapy.

Cryopyrin-associated periodic syndromes (CAPS), also known as NLRP3-associated autoinflammatory diseases, are a spectrum of rare autoinflammatory diseases caused by gain-of-function variants in the NLRP3 gene, resulting in inflammasome hyperactivation and dysregulated release of interleukin-1β (IL-1β). Many patients with CAPS develop progressive sensorineural hearing loss (SNHL) because of cochlear autoinflammation, which may be the sole manifestation in rare cases. This study was undertaken to establish the suspected diagnosis of CAPS in a family presenting with autosomal-dominant progressive/acute SNHL and a novel missense variant in the NLRP3 gene of unknown significance (NM_001079821.3:c.1784G>A p.Ser595Asn). We conducted an ex vivo functional assessment of the NLRP3 inflammasome in heterozygous individuals (n=10) and healthy family members (n=5). The assay revealed hyperactivation of the inflammasome among heterozygous individuals, supporting the hypothesis that this missense variant is a pathogenic gain-of-function variant. Administration of IL-1 receptorantagonist resulted in a substantial clinical improvement among pediatric patients, who exhibited near resolution of hearing impairment within 1 to 3 months of treatment. Our findings highlight the crucial role of early diagnosis and treatment with an anti-IL-1 agent in reversing cochlear damage. Furthermore, our results suggest that high- and ultrahigh-frequency ranges need to be included in the auditory assessment to enable early detection of subclinical SNHL. Finally, incorporating functional inflammasome assessment as part of the clinical evaluation could establish the diagnosis in inconclusive cases.

Bilateral vestibulopathy and sensorineural hearing loss in necrobiotic xanthogranuloma, multiple myeloma and amiloidosis

This article describes a rare case of necrotic xanthogranuloma in a 46-year-old patient who presented with the development of periorbital xanthelasms, progressive bilateral sensorineural hearing loss and bilateral vestibulopathy, followed by multiple myeloma and amyloidosis. For several years, the patient underwent standard rehabilitation for chronic sensorineural hearing loss and was fitted with a hearing aid. During hospitalisation for exacerbation of chronic bronchitis, monoclonal gammopathy was identified, and later, after careful examination and repeated biopsies, necrotic xanthogranuloma, multiple myeloma and AL-amyloidosis were confirmed. Targeted immunochemotherapy resulted in improvement of hearing and significant recovery of the vestibuloocular reflex bilaterally.

Late-onset of Labyrinthine Dysfunction in Chronic Brucella-induced Encephalitis

Brucellosis, caused by Brucella, dominates in the Middle East. Acute or chronic brucellosis can involve any organ system, and the involvement of the central nervous system leads to encephalitis, called neurobrucellosis (NB). We report a rare case from north India where a variant of Brucella caused NB led to progressive labyrinthine dysfunction; who developed vertigo, disequilibrium, and gradual progressive sensorineural (SN) hearing loss. Audiological tests pure-tone audiometry (PTA), otoacoustic emissions (OAE), stapedial muscle reflexes, auditory evoked brainstem responses (ABR), and vestibular evoked myogenic potentials (VEMPs) were conducted on the patients. PTA showed a bilateral profound SN hearing loss, an absent OAE, and ABR suggestive of cochlear dysfunction. The cervical and ocular VEMP showed delayed n1 and p1 latencies, suggesting superior and inferior nerve branch involvement. Vertigo or disequilibrium and SN hearing loss can be the late-onset manifestations of labyrinthine dysfunction in chronic Brucella-induced encephalitis.

A novel model of sensorineural hearing loss induced by repeated exposure to moderate noise in mice: the preventive effect of resveratrol.

Sensorineural hearing loss (SNHL) induced by noise has increased in recent years due to personal headphone use and noisy urban environments. The study shows a novel model of gradually progressive SNHL induced by repeated exposure to moderate noise (8-kHz octave band noise, 90-dB sound pressure level) for 1 hr exposure per day in BALB/cCr mice. The results showed that the repeated exposure led to gradually progressive SNHL, which was dependent on the number of exposures, and resulted in permanent hearing loss after 5 exposures. Repeated exposure to noise causes a loss of synapses between the inner hair cells and the peripheral terminals of the auditory nerve fibers. Additionally, there is a reduction in the expression levels of c-fos and Arc, both of which are indicators of cochlear nerve responses to noise exposure. Oral administration of resveratrol (RSV, 50 mg/kg/day) during the noise exposure period significantly prevented the noise exposure-induced synapse loss and SNHL. Furthermore, the study found that RSV treatment prevented the noise-induced increase in the gene expression levels of the proinflammatory cytokine interleukin-1β in the cochlea. These results demonstrated the potential usefulness of RSV in preventing noise-induced SNHL in the animal model established as gradually progressive SNHL.

Hyperglycemia with hypogonadism and growth hormone deficiency in a 17-year-old male with H syndrome: the first case report from Syria

BackgroundThe nucleoside transport capabilities of the human equilibrative nucleoside transporter-3 (hENT3) are disrupted by mutations in SLC29A3 (10q22.2), which are genes for the nucleoside transporter and are the cause of the unusual autosomal recessive disease known as H syndrome. As a result, histiocytic cells invade a number of organs.Case presentationA 17-year-old Syrian male was admitted to the internal medicine department with a one-month history of polyuria, polydipsia, general weakness, and pallor. He had a history of progressive bilateral sensorineural hearing loss and failure to gain weight for three years. Physical examination revealed various abnormalities, including scrotal mass, small penis and testicles, absence of pubic and axillary hair, joint abnormalities, short stature, hallux valgus, fibrous protrusion near the navel, and hyperpigmented non-itchy painful skin plaques. Clinical signs along with laboratory test results confirmed hyperglycemia, primary hypogonadism, osteopenia, and growth hormone deficiency. After a review of the relevant medical literature, this patient’s presentation of hyperglycemia with hypogonadism, hyperpigmentation, hallux valgus, hearing loss, hematological abnormalities, and short stature suggested the diagnosis of H syndrome. The patient received treatment with insulin and testosterone, leading to a significant improvement in his presenting symptoms.ConclusionsH syndrome is a very rare condition, and the fact that the first case has only recently been reported in Syria serves to emphasize how rare it is. H Syndrome should be suspected if a patient has short stature with signs of hyperglycemia and other endocrine and cutaneous abnormalities. We are reporting this case to increase physicians’ awareness of this exceedingly rare and unique syndrome.

Novel autosomal dominant TMC1 variants linked to hearing loss: insight into protein-lipid interactions

BackgroundTMC1, which encodes transmembrane channel-like protein 1, forms the mechanoelectrical transduction (MET) channel in auditory hair cells, necessary for auditory function. TMC1 variants are known to cause autosomal dominant (DFNA36) and autosomal recessive (DFNB7/11) non-syndromic hearing loss, but only a handful of TMC1 variants underlying DFNA36 have been reported, hampering analysis of genotype-phenotype correlations.MethodsIn this study, we retrospectively reviewed 338 probands in an in-house database of genetic hearing loss, evaluating the clinical phenotypes and genotypes of novel TMC1 variants associated with DFNA36. To analyze the structural impact of these variants, we generated two structural models of human TMC1, utilizing the Cryo-EM structure of C. elegans TMC1 as a template and AlphaFold protein structure database. Specifically, the lipid bilayer-embedded protein database was used to construct membrane-embedded models of TMC1. We then examined the effect of TMC1 variants on intramolecular interactions and predicted their potential pathogenicity.ResultsWe identified two novel TMC1 variants related to DFNA36 (c.1256T > C:p.Phe419Ser and c.1444T > C:p.Trp482Arg). The affected subjects had bilateral, moderate, late-onset, progressive sensorineural hearing loss with a down-sloping configuration. The Phe419 residue located in the transmembrane domain 4 of TMC1 faces outward towards the channel pore and is in close proximity to the hydrophobic tail of the lipid bilayer. The non-polar-to-polar variant (p.Phe419Ser) alters the hydrophobicity in the membrane, compromising protein-lipid interactions. On the other hand, the Trp482 residue located in the extracellular linker region between transmembrane domains 5 and 6 is anchored to the membrane interfaces via its aromatic rings, mediating several molecular interactions that stabilize the structure of TMC1. This type of aromatic ring-based anchoring is also observed in homologous transmembrane proteins such as OSCA1.2. Conversely, the substitution of Trp with Arg (Trp482Arg) disrupts the cation-π interaction with phospholipids located in the outer leaflet of the phospholipid bilayer, destabilizing protein-lipid interactions. Additionally, Trp482Arg collapses the CH-π interaction between Trp482 and Pro511, possibly reducing the overall stability of the protein. In parallel with the molecular modeling, the two mutants degraded significantly faster compared to the wild-type protein, compromising protein stability.ConclusionsThis results expand the genetic spectrum of disease-causing TMC1 variants related to DFNA36 and provide insight into TMC1 transmembrane protein-lipid interactions.

A Retrospective Study of Clinical Profile of Patients with Autoimmune Inner Ear Disease.

Bilateral sensorineural hearing loss can be a very distressing symptom and can affect the efficiency of a person and one's quality of life. Conditions causing bilateral hearing loss are very few and autoimmune aetiology is one of them. Autoimmune ear disease is characterised by bilateral, mostly fluctuating audiovestibular symptoms and symptoms which respond to steroids. Diagnosis of AIED presents a unique challenge to clinicians due to the lack of standardized diagnostic criteria or reliable pathognomonic tests. The purpose of the study is to evaluate the patients who fit into criteria of autoimmune inner ear disease and understand the clinical features and response to medications for the same. A retrospective chart review of patients presenting with rapidly progressive bilateral hearing loss was done. The clinical presentation including detailed history and examination findings along with the blood investigation reports and audiograms were recorded in a tabular form. The study included 6 patients - 3 male and 3 female patients. Age of the patients at onset of hearing loss varied between 24-35 years. 3 of 6 patients presented with primary autoimmune ear disease and other 3 had hearing loss secondary to systemic autoimmune disease. All patients were treated with systemic steroids, but however showed a varied response. Patients with primary AIED were administered inner ear steroid therapy as well. AIED is thus a diagnosis of exclusion done with high index of suspicion. Patients with bilateral progressive sensorineural hearing loss should be evaluated for autoimmune etiology. Oral steroids with intratympanic steroids are currently the mainstay of treatment for AIED. Guarded prognosis of hearing improvement is noted in these patients. Hence, emphasis should be placed on early hearing rehabilitation for better quality of life.