Identification of common stria vascularis cellular alteration in sensorineural hearing loss based on ScRNA-seq.

BACKGROUND: The stria vascularis (SV), located in the lateral wall of the cochlea, maintains cochlear fluid homeostasis and mechanoelectrical transduction (MET) activity required for sound wave conduction. The pathogenesis of a number of human inheritable deafness syndromes, age related hearing loss, drug-induced ototoxicity and noise-induced hearing loss results from the morphological changes and functional impairments in the development of the SV. In this study, we investigate the implications of intercellular communication within the SV in the pathogenesis of sensorineural hearing loss (SNHL). We aim to identify commonly regulated signaling pathways using publicly available single-cell transcriptomic sequencing (scRNA-seq) datasets. METHODS: We analyzed scRNA-seq data, which was derived from studying the cochlear SV in mice with SNHL compared to normal adult mice. After quality control and filtering, we obtained the major cellular components of the mouse cochlear SV and integrated the data. Using Seurat's FindAllMarkers and FindMarkers packages, we searched for novel conservative genes and differential genes. We employed KEGG and GSEA to identify molecular pathways that are commonly altered among different types of SNHL. We utilized pySCENIC to discover new specific regulatory factors in SV subpopulation cells. With the help of CellChat, we identified changes in subpopulation cells showing similar trends across different SNHL types and their alterations in intercellular communication pathways. RESULTS: Through the analysis of the integrated data, we discovered new conserved genes to SV specific cells and identified common downregulated pathways in three types of SNHL. The enriched genes for these pathways showing similar trends are primarily associated with the Electron Transport Chain, related to mitochondrial energy metabolism. Using the CellChat package, we further found that there are shared pathways in the incoming signaling of specific intermediate cells in SNHL, and these pathways have common upstream regulatory transcription factor of Nfe2l2. Combining the results from pySCENIC and CellChat, we predicted the transcription factor Nfe2l2 as an upstream regulatory factor for multiple shared cellular pathways in IC. Additionally, it serves as an upstream factor for several genes within the Electron Transport Chain. CONCLUSION: Our bioinformatics analysis has revealed that downregulation of the mitochondrial electron transport chain have been observed in various conditions of SNHL. E2f1, Esrrb, Runx1, Yy1, and Gata2 could serve as novel important common TFs regulating the electron transport chain. Adm has emerged as a potential new marker gene for intermediate cells, while Itgb5 and Tesc show promise as potential new marker genes for marginal cells in the SV. These findings offer a new perspective on SV lesions in SNHL and provide additional theoretical evidence for the same drug treatment and prevention of different pathologies of SNHL.

The serum IgG antibody level as a biomarker for clinical outcome in patients with cerebral sparganosis after treatment.

Introduction: Cerebral sparganosis is a rare parasitic infection of the brain tissue. The remission of MRI change and clinical symptom has been used to evaluate the therapeutic effect. However, there is no study to correlate the serum IgG antibody level of sparganum to the prognosis of disease after treatment. Methods: 87 patients with cerebral sparganosis were collected from three medical centers. Clinical symptoms and MRI changes were evaluated at 12 months after initial treatment, and serum IgG antibody level of sparganum was evaluated at 2, 6, and 12 months after treatment. The positive cut-off value was based on 2.1 times the optical density (OD) of negative control. The index value was defined as the sample OD divided by the cut-off value. Results: Among the 87 patients after treatment, 71 patients had good clinical outcomes, and 16 had poor clinical outcomes. The area under the curve (AUC) showed that the index value measured at 12 months after treatment had the best prediction effect, with a value of 2.014. In the good-outcome group, the index values were less than 2.014 in all 71 patients, and only 8 patients had mildly enhanced residual lesions on MRI. In the poor-outcome group, the index values were more than 2.014 in all 16 patients, and all patients still showed significantly enhanced lesions on MRI. Compared with poor-outcome patients, only 2 patients with good outcomes had disease recurrence after treatment. Discussion: This study provided evidence that the serum IgG antibody level of sparganum was a promising biomarker to evaluate the prognosis of patients with cerebral sparganosis after treatment.

Genetic spectrum in a cohort of patients with distal hereditary motor neuropathy.

BACKGROUND: Distal hereditary motor neuropathy (dHMN) is a heterogeneous group of diseases characterized by exclusive degeneration of peripheral motor nerves, while only 20.0-47.8% of dHMN patients are genetically identified. Recently, GGC expansion in the 5'UTR of NOTCH2NLC has been associated with dHMN. Accordingly, short tandem repeat (STR) should be further explored in genetically unsolved patients with dHMN. METHODS: A total of 128 patients from 90 unrelated families were clinically diagnosed as dHMN, and underwent a comprehensively genetic screening. Skin biopsies were conducted with routine protocols. RESULTS: Most patients showed chronic distal weakness of lower limbs (121/128), while 20 patients initially had asymmetrical involvements, 14 had subclinical sensory abnormalities, 11 had pyramidal impairments, five had cerebellar disturbance, and four had hyperCKmia. The rate of genetic detection was achieved in 36.7% (33/90), and the rate increased to 46.7% (42/90) if patients with variants uncertain significance were included. The most common causative genes included chaperone-related genes (8/33, 24.2%), tRNA synthetase genes (4/33, 12.1%), and cytoskeleton-related genes (4/33, 12.1%). Additionally, two dominant inherited families were attributed to abnormal expansion of GGC repeats in the 5'UTR of NOTCH2NLC; and a patient with dHMN and cerebellar symptoms had CAG repeat expansion in the ATXN2 gene. Skin biopsy from patients with GGC expansion in NOTCH2NLC revealed typical intranuclear inclusions on histological and ultrastructural examinations. INTERPRETATIONS: This study further extends the genetic heterogeneity of dHMN. Given some dHMN patients may be associated with nucleotides repeat expansion, STR screening is necessary to perform in genetically unsolved patients.

Benign monomelic amyotrophy of lower limb in a cohort of chinese patients.

BACKGROUND: Benign monomelic amyotrophy of lower limb (BMALL) is a neurogenic syndrome representing an unclear field. Further studies might be helpful to elucidate uncertainties regarding causation, outcome, and the risk of progression to amyotrophic lateral sclerosis (ALS). METHODS: According to the inclusion and exclusion criteria, 37 patients with BMALL were retrospectively collected in three neuromuscular centers from January 2012 to October 2018. The detailed medical data were summarized. Multiple laboratory tests were examined. Routine electrophysiological examinations, muscle MRI of lower limbs, and muscle biopsy were conducted. RESULTS: The cohort included 24 male and 13 female cases with median age of onset 47 years. Muscle MRI revealed that the distribution of involved muscles matched with the extent of fat infiltration, so the pattern muscle atrophy can be divided into the following four types: six patients with thigh atrophy (type I), 14 patients with leg atrophy (type II); 10 patients with disproportionate atrophy in both thigh and leg (type III); and seven patients with well-proportionate atrophy in both thigh and leg (type IV). Electrophysiological findings showed neurogenic pattern, spontaneous activity, and abnormal H reflex, which suggested a disorder of spinal anterior horn cell in the patients with types I-III. However, no electrophysiological abnormalities were found in the patients with type IV. Muscle pathology varied from almost normal pattern to advanced neurogenic pattern in nine biopsied patients. Follow-up showed that two patients with type II developed to ALS four years later, and all patients with type IV were in stable condition without any complaints. CONCLUSION: Muscle MRI was useful to exactly localize the distribution of involved muscles in BMALL patients. The distribution of atrophic muscles can be roughly divided into four types based on the MRI features. The classification of distributing types might be as an indicator for the prognosis of BMALL.

Risk factors analysis of attention deficit/hyperactivity disorder and allergic rhinitis in children: a cross-sectional study.

BACKGROUND: To investigate the relationship between symptom of attention-deficit/hyperactivity disorder (ADHD) and allergic rhinitis (AR) in AR children of different genders and ages. METHODS: Four hundred and sixty-five allergic rhinitis children aged 6-12 years old were recruited in this study. Skin-prick test, Pediatric Rhinoconjunctivitis Quality of Life Questionnaire (PRQLQ), Total Nasal Symptoms Score (TNSS) and the Swanson, Nolan, and Pelham version IV scale (SNAP-IV) were recorded. Patients were divided into AR with ADHD and AR without ADHD, according to the SNAP-IV scale results. RESULTS: Children with the inattention/hyperactivity scale (IHS) > 1.25 accounted for 26.4% of all children with AR. The TNSS with IHS > 1.25 group were significantly higher than the IHS ≤ 1.25 group. Univariate analysis showed that age, gender, duration of AR symptoms, skin index, and PRQLQ subscales were associated with symptoms of hyperactivity and attention deficit (IHS > 1.25). After normalizing the age and gender factors, duration of AR symptoms and skin index correlated with IHS > 1.25. After stratifying age and gender, the correlation between IHS > 1.25 and skin index and PRQLQ subscales was mainly found in male children, and the association between the duration of AR symptoms and IHS > 1.25 was reflected in each group. CONCLUSIONS: ADHD in children with AR is associated with severity, duration, and skin index of AR, and this association is more pronounced in male children.

Clinical Analysis of Sphenoid Sinus Mucocele With Initial Neurological Symptoms.

BACKGROUND AND OBJECTIVES: Neurological manifestations associated with sphenoid sinus mucocele (SSM) are easily misdiagnosed due to nonspecific symptoms. The objective is to analyze and report the clinical features of SSM presenting with neurological manifestations, to allow an earlier diagnosis and more timely intervention for this disease. METHODS: This was a retrospective cross-sectional study including 19 patients. The detailed clinical information of 19 patients with the initial symptom of neurological manifestations caused by SSM presenting at the Second Affiliated Hospital of Wenzhou Medical University between January 2000 and May 2018 were retrospectively analyzed. Collected data including symptoms, signs, neuroimaging, and pathologic diagnoses. RESULTS: There were eleven males and 8 females, and their ages ranged from 23 to 71 years. Headache was the most frequent symptom, in 12 of the 19 patients presenting as the initial symptom. The visual disturbance included visual loss (4/19), diplopia (3/19), and another patient had both visual loss and diplopia. Neurophysical examination found that 4 patients presented with oculomotor nerve palsy, 4 patients had optic nerve or abducens nerve palsy, and 1 patient had optic neuropathy, oculomotor nerve palsy and abducens nerve palsy simultaneously. All patients underwent endoscopic surgery and had postoperative clinical symptom improvement. CONCLUSIONS: Headache is the most common symptom of SSM and should be on the differential diagnosis of patients presenting with headache, even if in isolation. The results suggest that CT and MRI are the best tools in diagnosis of SSM and endoscopic sphenoidotomy is a safe and effective method in the treatment of SSM.

Genetic Polymorphisms and Susceptibility to Sudden Sensorineural Hearing Loss: A Systematic Review.

BACKGROUND: Recently, genetic factors have been considered as an important risk factor for sudden sensorineural hearing loss (SSNHL). Many studies analyzed the association between SSNHL and polymorphisms. However, most of them gave inconclusive results. Key Message: We performed a systematic review to find out the association between polymorphisms and susceptibility to SSNHL. Finally, 47 studies involving 5,230 SSNHL patients and 68 genes were included for analysis and discussion of results. Polymorphisms in 26 genes have been suggested to be correlated with the susceptibility to SSNHL. SUMMARY: Although a great number of studies support that polymorphisms in genes are associated with susceptibility to SSNHL, we need large multicenter studies, which evaluate multiple single nucleotide polymorphisms in SSNHL patients, to find real genetic risk factors for susceptibility to SSNHL. This is very helpful in designing more effective prevention and treatment strategies for patients with SSNHL.

Prognostic role of haematological indices in sudden sensorineural hearing loss: Review and meta-analysis.

BACKGROUND: Complete blood count (CBC) is an important blood test in clinical practice, and it has been recently used to predict the prognosis of patients with sudden sensorineural hearing loss (SSNHL). Some haematological indices of the CBC test have been reported to be associated with the clinical outcome of SSNHL. However, the prognostic value of these haematological indices in SSNHL is currently under debate. Here, we performed a meta-analysis to investigate the association between haematological indices of the CBC test and clinical outcomes in patients with SSNHL. METHODS: We conducted a meta-analysis of studies that evaluated the association between haematological indices and prognoses in patients with sudden hearing loss. Subgroup and sensitivity analyses were also performed to explore potential sources of heterogeneity. RESULTS: Ten studies that included 972 individuals were identified. Pooled analysis showed neutrophil-to-lymphocyte ratio (NLR) (weighted mean difference [WMD] = -1.69 and p < 0.001), platelet-to-lymphocyte ratio (PLR) (WMD = -38.45 and p < 0.001), neutrophil count (WMD = -1.57 × 109/L and p < 0.001) and lymphocyte count (WMD = 0.41 × 109/L and p < 0.001) to be the factors associated with the prognosis of SSNHL. CONCLUSIONS: Our findings indicated that NLR, PLR, neutrophil count and lymphocyte count are strongly associated with the prognosis of SSNHL. These four indices could be recommended as inexpensive markers to report treatment outcomes.

Association of pediatric allergic rhinitis with the ratings of attention-deficit/hyperactivity disorder.

BACKGROUND: Allergic rhinitis (AR) is currently the most prevalent allergic disease in children and adolescents. OBJECTIVE: Surveys conducted by population-based studies of East Asia revealed an increased prevalence of behavioral disorders in patients with AR. Thus, in this study, we explored the prevalence of attention-deficit/hyperactivity disorder (ADHD) in pediatric patients with AR. METHODS: A total of 333 children (6-12 years of age) with AR and a total of 322 age-matched controls were included in this study. An otorhinolaryngologist diagnosed all AR cases and evaluated the severity of the disease. Skin-prick test results for 18 major allergens, Paediatric Rhinoconjunctivitis Quality of Life Questionnaire (PRQLQ), Child Behavior Checklist (CBCL), and Swanson, Nolan, and Pelham version IV (SNAP-IV) scores were recorded. RESULTS: In total, 320 age-matched controls and 323 children with AR completed the study. With respect to the Total Nasal Symptom Score and the PRQLQ, the condition of the experimental group was more serious than that of the controls. The scores on the hyperactivity/impulsivity and inattention subscales, which evaluate ADHD symptoms, and those on the CBCL subscales were significantly higher in patients with AR than in the controls (all p values were <0.01). From the results of the Pearson correlation, we deduced that there were significant positive correlations between the AR-related data and each subscale of the CBCL and SNAP-IV in the AR group. Moreover, two basic characteristics (males and environmental exposure to tobacco smoke) present significant positive and age showed a significant negative correlations affect ADHD symptom in both the AR group and the control group. Also, in the "pure AR" group, hierarchical regression analyses were performed to determine the subtests of the PRQLQ, which are significant predictors of SNAP-IV and CBCL. CONCLUSIONS: Apart from AR per se, the possible comorbidities of impulsivity and inattention are important when managing children with AR. It is essential to evaluate the symptoms of ADHD in children and adolescents with AR.

Efficacy of Sublingual Immunotherapy for House Dust Mite-Induced Allergic Rhinitis: A Meta-Analysis of Randomized Controlled Trials.

PURPOSE: Allergic rhinitis (AR) has become a global issue for a large part of the general population. Sublingual immunotherapy (SLIT) has been used extensively to treat persistent allergic rhinitis (PAR). Although systematic reviews have confirmed the effectiveness of SLIT for the treatment of AR, a considerable number of studies using extracts of house dust mites (HDMs) for immunotherapy found no consensus on basic treatment parameters and questioned the efficacy of SLIT. METHODS: In this study, we evaluated SLIT for PAR by a meta-analysis of randomized controlled trials (RCTs). Medline, Embase, and Cochrane Library database searches were performed for RCTs on the treatment of PAR by SLIT that assessed clinical outcomes related to efficacy through May 2016. Descriptive and quantitative information was abstracted. An analysis was performed with standardized mean differences (SMDs) under a fixed or random effects model. Subgroup analyses were performed. Heterogeneity was assessed using the I² metric. RESULTS: In total, 25 studies were eligible for inclusion in the meta-analysis for symptom scores and 15 studies for medication scores. SLIT was significantly different from the controls for symptom scores (SMD=1.23; 95% confidence interval [CI]=1.74 to 0.73; P<0.001). For medication scores, significant differences for SLIT were also observed versus the controls (SMD=-1.39; 95% CI=-1.90 to -0.88; P<0.001). CONCLUSIONS: Our meta-analysis indicates that SLIT provided significant symptom relief and reduced the need for medications in PAR. In this study, significant evidence was obtained despite heterogeneity with regard to the use of mite extract. Specifically, the mite extract used was provided by the patients with PAR. Furthermore, to confirm both the objective outcomes and the effective doses of HDM allergen extracts, experimental data should be obtained from large high-quality population-based studies.

Efficacy and safety of sublingual immunotherapy for allergic rhinitis in pediatric patients: A meta-analysis of randomized controlled trials.

BACKGROUND: Allergic rhinitis (AR) has become a global health problem that constantly affects a large part of the general population, especially children. OBJECTIVE: Sublingual allergen immunotherapy (SLIT) has been used extensively for pediatric AR, although its efficacy and safety are often questioned. In this meta-analysis of randomized controlled trials (RCT), we evaluated the use of SLIT for pediatric AR. METHODS: A number of medical literature data bases were searched through January 2016 to identify RCTs that examined the use of SLIT for pediatric AR and that assessed clinical outcomes related to efficacy. Descriptive and quantitative information was abstracted. Standardized mean differences (SMD) were calculated by using fixed- and random-effects models. Subgroup analyses were performed. Heterogeneity was assessed by using the I2 metric. A network meta-analysis was used to estimate SMDs between two SLIT protocols for pediatric seasonal AR. All data were extracted from publications or received from the authors. RESULTS: Twenty-six studies were eligible for inclusion in the meta-analysis of rhinitis or rhinoconjunctivitis symptom scores, and 19 studies were eligible for the meta-analysis of medication scores. Descriptive and quantitative data were extracted. SLIT differed significantly from placebo in terms of symptom scores (SMD -0.55 [95% confidence interval {CI}, -0.86 to -0.25]; p = 0.0003, I2 = 90%) and medication scores (SMD -0.67 [95% CI, -0.96 to -0.38]; p < 0.00001, I2 = 83%). Oral pruritus was the adverse effect, which occurred most commonly in children who were receiving SLIT. Network meta-analysis revealed no significant difference between the pre-coseasonal and continuous SLIT protocols for seasonal AR in symptom scores (SMD -6.55 [95% CI, -25.38 to 12.29]; p = 0.496) and medication scores (SMD -8.83 [95% CI, -22.10 to 4.43]; p = 0.192). CONCLUSIONS: Our meta-analysis results indicated that SLIT provided significant symptom relief and reduced the need for medication in pediatric patients. Moreover, the safety of SLIT needs to be confirmed in RCTs with larger samples.

[Function study of non-syndromic deafness associated mitochondrial 12S rRNA A839G mutation].

OBJECTIVE: To investigate the correlation between nonsyndromic deafness and mitochondrial 12s rRNA A839G mutation. METHODS: According to the clinical manifestations of mitochondrial DNA sequencing and analysis to find and determine family containing mitochondrial 12s rRNA A839G mutation. Harvested its family members blood and transferred their lymphocytes into lymphoblastoid cell lines, followed by cells cultured, cell doubling experiment, susceptibility testing, cellular oxygen consumption rate experiment, ROS and mitochondrial membrane potential experimental tests were progressed to explore the correlation between the A839G mutation and nonsyndromic deafness. RESULTS: The mitochondrial 12s rRNA A839G mutation pedigrees were determined through the full sequence detections of the Mitochondrial DNA, further phylogenetic analysis showed that 839 point conservative index (CI) up to 78.6%; in RPMI-galactose medium containing A839G gene mutant cell line, the doubling time was significantly longer than the control group, and the difference was significant (P = 0.033). The effect to cell lines containing the A839G mutation of aminoglycoside drugs was not obvious. When compared with the control group, cell lines containing the A839G mutation significantly reduced cellular oxygen consumption rate(P = 0.033); compared with the control group, the ROS levels of cell lines containing the A839G mutation appeared more substantial elevated with significan difference (P < 0.01). The mitochondrial membrane potential of cells of experimental group was significantly reduced than the control group. CONCLUSION: The present study proved that the mitochondria 12s rRNA A839G mutations affect the function of the mitochondrial respiratory chain at the cell level, which might reduce the growth rate of the mutant cell lines, result in hearing.

[Juvenile onset respiratory papillomatosis: risk factors for severity].

OBJECTIVE: This study was designed to explore the risk factors associated with severity of juvenile onset recurrent respiratory papillomatosis. METHOD: A retrospective study was conducted to study determinants of severe forms of juvenile recurrent onset respiratory papillomatosis. The patients were separated into different groups based on the onset age, the first recurrence of age, the first recurrence of period, gender and incision of tracheal respectively. The relationship among the lesion severity score,the involvement of the subregion, operation period and the next operation period were also explored. RESULT: It was observed that some children who recurred before 4 years old required more surgery, shorter operation period(the average, longest or shortest operation period) than those elder children, the differences were statistically (P=0. 029, 0. 003, 0. 010, 0. 039, respectively). The severity score of lesion was correlated positively with the involvement of the subregion and negatively with operation period (r=0. 914, -0. 451, respectively). Some children who diagnosed before 4 years old had to endure more severity score and shorter operation period than those older children, the differences were statistically (P= 0. 036, 0. 000, respectively). 8 cases accepted incision of tracheal, they accepted more surgery too. But the differences in the onset age, the first recurrence of age, and the operation period were not statistically. CONCLUSION: The results showed that the clinical course of juvenile onset recurrent respiratory papillomatosis was closely related to the first recurrence age and period, while the severity of disease was associated to the onset age and the involvement of the subregion.

[Levels of serum IL-4, IFN-gamma, IL-32 in children with juvenile-onset recurrent respiratory papillomatosis].

OBJECTIVE: To explore the relationship between serum IL-4, IFN-gamma, IL-10 levels and the aetiology of juvenile-onset recurrent respiratory papillomatosis. METHOD: Serum IL-4, IFN-gamma, IL-32 levels of 15 JORRP children were detected by use of enzyme-linked immunosorbent assay (ELISA) and compared with those of healthy control group. RESULT: Serum IL-4 levels were significantly higher in the JORRP children (P<0.01): (524.65 +/- 147.77)pg/ml in the JORRP children and (213.27 +/- 87.48) pg/ml in the healthy control group. Serum IFN-gamma levels were significantly lower in the JORRP children (P<0.01): (2.87 +/- 0.84) pg/ml in the JORRP children and (10.63 +/- 5.09) pg/ml in the healthy control group. Serum IL-32 levels were significantly lower in the JORRP children (P< 0.01): (2.47 +/- 1.60) pg/ml in the JORRP children and (9.08 +/- 2.66) pg/ml in the healthy control group. CONCLUSION: 1) While the concentration of Th2 like cytokine IL-4 in children with JORRP was higher than that in control group, the concentration of Th1 like cytokine IFN-gamma in children with JORRP was lower than that in controls, indicating that the polarization of Th1 /Th2 T cell in children with JORRP; 2) The polarization of Th1/Th2 T cell may cause the reduction of the serum IL-32 as a proinflammatory role in host immunity system that could not eradicate HPVs because of lacking enough inflammatory stimulation.

[Analysis of genotype-phenotype correlation for GJB2 in 221 non-syndromic deafness probands and their pedigrees].

OBJECTIVE: To assess the possible genotype-phenotype correlation for GJB2. METHODS: Retrospectively analyzed GJB2 gene mutations with non-syndromic hearing impairment (NSHI) patients and their families audiological data. Individuals were grouped, according to non-truncated mutant (non-truncating, NT) and truncating mutations (truncating, T), into T/T group, T/NT group and NT/NT group. And according to whether they carry 235delC, grouped into 235delC/235delC group, 235delC/Non-235del group and Non-235delC/Non-235delC group. RESULTS: Grouped according to whether the truncation mutants:Fisher exact statistical analysis showed that the degree of hearing loss among the three groups did not meet the random distribution (P = 0.003) , T/T group was significantly higher than T/NT group (P = 0.000) and NT/NT group (P = 0.000) on the degree of hearing loss. Grouped according to whether they carry 235delC mutation: degrees of hearing loss among the three groups were statistically significant differences. Respectively pairwise comparisons (Fisher exact test) found 235delC/235delC group was significantly higher than 235delC/Non-235delC on the degree of hearing loss group (P = 0.001) and Non-235delC/Non-235delC group (P = 0.000), 235delC/Non-235delC group higher than Non-235delC/Non-235delC group (P = 0.033). In GJB2 mutations homozygous and compound heterozygous mutation genotype:G109A/G109A, 235delC/512insAACG, 299delAT/G109A and 235delC/G109A degree of hearing loss caused by genotype was significantly lower than 235delC/235delC group. CONCLUSIONS: 235delC homozygotes have significantly more hearing impairment, when compared with 235delC/non-235delC compound heterozygotes. People with two non-235delC mutations have even less hearing impairment. Patients with non-truncation mutants (G109A) suffer from lighter hearing loss than truncation mutations(235delC, 299delAT).