The etiology of otosclerosis: a combination of genes and environment

History of Eugenics in Otorhinolaryngology: Ernst Rüdin and the International Eugenics Network

Introduction  The early geneticist and psychiatrist Ernst Rüdin (1874-1952) became one of the key figures in the eugenics movement and in the German health system of the Nazi era. His connections in the international eugenics network have played an important role in the history of eugenics. Objective  To discuss the connections between Ernst Rüdin's scientific group in Munich and Otmar von Verschuer's group in Frankfurt during the Nazi era. Methods  Otorhinolaryngological materials from Ernst Rüdin's former private library are presented, and they show Rüdin's deep involvement in the international eugenics network. These materials provide insights into early medical genetics in otorhinolaryngology. Results  One result of the present study is that eugenics groups from Munich, Frankfurt, and New York certainly influenced one another in the field of otorhinolaryngology. Karlheinz Idelberger and Josef Mengele were two scientists who performed hereditary research on orofacial clefts. Later, Mengele became deeply involved in Nazi medical crimes. His former work on orofacial clefts clearly had, to some extent, an influence on subsequent studies. Conclusion  An international eugenics network already existed before 1933. However, it becomes clear that the weaknesses of many early genetic studies did not enable its authors to draw firm scientific conclusions, suggesting that scientists lacked an accurate concept of the genetic causes of most illnesses.

Factors Associated With Hearing Outcomes After Stapedotomy in Taiwanese Patients With Clinical Otosclerosis

OBJECTIVE

To examine the clinical factors associated with the effectiveness of stapedotomy in improving hearing sensitivity in Taiwanese patients with otosclerosis.

METHODS

In this retrospective study, we reviewed the medical records of 31 patients (36 ears) with otosclerosis undergoing stapedotomy performed by a single surgeon. Preoperative and postoperative hearing results were analyzed to identify factors associated with hearing outcomes after stapedotomy in the Taiwanese population with clinical otosclerosis.

RESULTS

Compared with preoperative pure tone averages (PTAs), stapedotomy significantly improved postoperative air conduction (AC) thresholds (P < .0001), bone conduction (BC) thresholds (P = .025), and air-bone gaps (ABGs; P < .0001). Postoperative closure of ABGs less than 10 or 20 dB was achieved in 16 (44.4%) and 33 (91.7%) of 36 surgical ears. Improvement in postoperative AC thresholds and ABGs and the size of preoperative ABGs were significantly correlated (r = .650, P < .001 and r = .745, P < .001, respectively). Gender-stratified analysis indicated a stronger correlation between improvement in postoperative AC thresholds and preoperative ABGs in male patients than in female patients (r = .893, P < .001 and r = .476, P = .014, respectively), and in postoperative and preoperative ABGs (r = .933, P < .001 and r = .626, P < .001, respectively). With the more stringent criteria for surgical success, factors including age (≤50 years), type (conductive, BC ≤25 dB), and degree (PTA ≤55 dB) of preoperative hearing loss led to more favorable outcomes.

CONCLUSIONS

We reported evidence supporting a potential gender difference on hearing outcomes after stapedotomy in Taiwanese patients with otosclerosis. Age, type, and degree of preoperative hearing loss may affect the surgical success rate.

Association between Otosclerosis and Rubella in Taiwan: A Nationwide Case-Control Study

Otosclerosis is an early adult-onset disease that is associated with 5-9% and 18-22% of all cases of hearing and conductive hearing loss, respectively, and it is suspected to have a viral etiology. However, the role of viral infection in otosclerosis is still inconclusive. This study aimed to investigate whether rubella infection was associated with otosclerosis risk. We conducted a nationwide case-control study in Taiwan. Data were retrospectively analyzed from the Taiwan National health Insurance Research Database. Cases consisted of all patients who were aged ≥6 years and had a first-time diagnosis of otosclerosis for the period between 2001 and 2012. The controls were exact matched to cases in a 4:1 ratio by birth year, sex, and must survive in the index year of their matched cases. Adjusted odds ratio (OR) and 95% confidence interval (CI) were estimated by using conditional logistic regression. We examined 647 otosclerosis cases and 2588 controls without otosclerosis. Among the 647 patients with otosclerosis, 241 (37.2%) were male and 406 (62.8%) were female, with most aged between 40 and 59 years, with a mean age of 44.9 years. After adjusting for age and sex, conditional logistic regression revealed that exposure to rubella was not associated with a significant increase in otosclerosis risk (adjusted OR, 2.0; 95% CI, 0.18-22.06, p = 0.57). In conclusion, this study did not show that rubella infection was associated with the risk of otosclerosis in Taiwan.

Conservative Otosclerosis Treatment With Sodium Fluoride and Other Modern Formulations: A Systematic Review

Otosclerosis, also known as otospongiosis, is a primary osteodystrophy of the otic capsule of the inner ear and one of the leading causes of deafness in adults. The rationale for medical therapy for otospongiosis is to slow down and eventually stop the phase of bone resorption. Conservative treatments include sodium fluoride (NaF), bisphosphonates, and other modern medicines. A systematic review of the existing and published articles and books until April 2021 has been conducted in Medscape, Google Scholar, PubMed, and other databases using appropriate terms. According to the results of the research, the administration of NaF for a period of at least six months stabilizes hearing thresholds (HTs), improves vestibular symptoms, and delays the worsening of tinnitus. The administration of bisphosphonates for a period of at least six months showed significant percentage differences in the improvement of hearing loss, dizziness, and tinnitus remission. In the already existing double-blind studies that were evaluated, groups of patients treated with bisphosphonates for at least 24 months showed greater stabilization of the mean air and bone conduction thresholds than groups of patients treated with a placebo. The new modern medications have not yet been widely administered clinically to draw useful conclusions, although the test results of some of their use are quite encouraging.

[Role of computed tomography in the preoperative diagnosis of otosclerosis]

BACKGROUND

Otosclerosis is an osteodystrophy of the otic capsule and presents with progressive conductive hearing loss. Imaging studies, especially computed tomography (CT) and cone-beam CT, have gained increased relevance in the diagnosis of otosclerosis.

OBJECTIVE

This study investigated whether there is a correlation between the extent of otosclerosis in high-resolution or cone-beam CT and hearing loss in pure-tone audiometry.

MATERIALS AND METHODS

Based on an existing classification of otosclerotic foci, a classification was established. Preoperative CT scans of patients undergoing stapedotomy between 2015 and 2019 were evaluated and classified by two independent otorhinolaryngologists. The preoperative pure-tone audiograms were analysed and compared to the results of CT.

RESULTS

A total of 168 CT studies (i.e., 168 ears) in 156 patients with intraoperatively confirmed otosclerosis were included in our study. A correlation between the extent of the otosclerotic focus or the calculated scores and hearing loss in pure-tone audiometry (air conduction, bone conduction and air-bone-gap) could not be proven.

CONCLUSION

Preoperative CT is not obligatory. However, preoperative imaging using CT or cone-beam CT can be helpful to confirm the diagnosis and exclude other middle or inner ear pathologies as well as in planning of the surgical procedure in the overall context of otoscopy and audiometry. A correlation with the degree of hearing impairment could not be demonstrated and remains unclear.

A new phenomenon of cochlear otosclerosis: an acquired or congenital disease? - A clinical report of cochlear otosclerosis

BACKGROUND

No cochlear otosclerosis in infants with congenital bilateral SNHL has been reported.

AIMS/OBJECTIVES

We report an infant male with bilateral cochlear otosclerosis, suggesting that cochlear otosclerosis may be a congenital disease and to further analyze the etiology of and genetic expression in congenital bilateral cochlear otosclerosis. We also describe the clinical characteristics and experience of patients with bilateral cochlear otosclerosis treated with cochlear implants (CIs).

MATERIALS AND METHODS

Seven patients, including an infant, who were diagnosed with cochlear otosclerosis underwent CI surgery. Their medical records, audiological and radiological results, surgical procedures, and CI outcomes were collected and reviewed.

RESULTS

The median age at hearing loss was 38 years, ranging from 0 to 47 years. The child had bilateral hearing loss at birth and received a CI at 1 year of age. He also had growth retardation and was diagnosed with 3q+/3p- syndrome. All patients (8 ears) had better postoperative auditory performance than that preoperatively.

CONCLUSIONS AND SIGNIFICANCE

Although cochlear otosclerosis often starts at middle age and progresses slowly, it may be a congenital disease that is related to chromosome abnormality. This disease presents with SNHL or MHL, and treatment with a CI is beneficial.

Hearing results after stapedotomy for otosclerosis: comparison of prosthesis variables

OBJECTIVE

To evaluate the influence of different piston variables on hearing following stapedotomy.

METHODS

Data were analysed in groups according to: piston material (titanium vs fluoroplastic), shaft diameter (0.4 mm vs 0.5 mm) and crimping style (manual crimping vs self-crimping). Pre- and post-operative average air-bone gap, air-bone gap difference, success rate and operative time were evaluated.

RESULTS AND CONCLUSION

Fifty-one patients (58 ears) were included. A post-operative air-bone gap of 10 dB or lower was achieved in 44 cases, with a success rate of 75.9 per cent; 52 cases (89.7 per cent) had an air-bone gap of 20 dB or lower. The success rate was higher, but not significantly, in fluoroplastic than in titanium pistons (85 per cent vs 70 per cent). Pistons with shaft diameters of 0.5 mm and 0.4 mm had success rates of 79 per cent and 72 per cent, respectively. No significant differences were found for any audiometric parameters. There were no significant differences between manual crimping and self-crimping pistons in terms of audiometric results or success rate.

Otosclerosis in an Urban Population

OBJECTIVE

To investigate the evolving prevalence of otosclerosis in a large urban population.

METHODS

A retrospective review of patients in a large, urban, public health system was conducted from January 2010 to August 2019 to identify subjects with otosclerosis. Diagnostic testing included audiometry and computed tomography scans. Sex, age at diagnosis, treatment received, race, ethnicity, and country of birth were analyzed for each subject and compared with all eligible patients in the reference population.

RESULTS

A total of 134 patients from a reference population of 672,839 were diagnosed with otosclerosis and analyzed. The otosclerosis patients were predominantly Hispanic (73%), of which the majority were foreign born (87%). The average age at onset was 46 years and 59% were women. The overall prevalence of otosclerosis was 20 of 100,000 patients. The crude prevalence of otosclerosis by ethnicity was 43 of 100,000 for Hispanics, 12.6 of 100,000 for Caucasians, and 3 of 100,000 for African Americans. Within the Hispanic population, the prevalence of otosclerosis was 60 of 100,000 for foreign-born individuals and 16 of 100,000 for those born in the USA (odds ratio [OR] = 3.69, [95% confidence interval [CI], 2.02-6.76], p < 0.0001). Prevalence was not significantly different among Caucasians and US-born Hispanics.

CONCLUSION

Otosclerosis in the studied population was most common among Hispanic patients, though it was strongly influenced by country of birth. The "imported" otosclerosis cases are best explained by environmental influence rather than ethnic susceptibility. This discrepancy is likely due to variance in measles immunization rates among North and Central American countries before 1990.

Pregnancy, Estrogen Exposure, and the Development of Otosclerosis: A Case-Control Study of 1196 Women

OBJECTIVE

This study sought to determine whether a history of pregnancy or bilateral oophorectomy is associated with subsequent otosclerosis development or disease severity.

STUDY DESIGN

Population-based case-control study.

SETTING

Olmsted County, Minnesota.

METHODS

Women diagnosed with otosclerosis were matched to 3 women without otosclerosis based on age and historical depth of medical records. Associations of prior delivery and bilateral oophorectomy with subsequent development of otosclerosis and with pure-tone average (PTA) at the time of otosclerosis diagnosis were evaluated.

RESULTS

We studied 1196 women: 299 cases of otosclerosis and 897 matched controls. The odds ratio for the association of ≥1 delivery with otosclerosis was 1.16 (95% confidence interval [CI] 0.85-1.60; P = .35). Odds ratios for the associations of 1, 2, 3, or ≥4 deliveries with otosclerosis were 1.22 (0.83-1.80), 1.09 (0.71-1.68), 1.28 (0.77-2.12), and 1.00 (0.54-1.84), respectively. The odds ratio for the association of prior bilateral oophorectomy with otosclerosis was 1.12 (0.58-2.18; P = .73). In cases with otosclerosis, PTA at diagnosis was not significantly higher for women with ≥1 delivery as compared with those without (median 45 dB hearing loss [HL] [interquartile range {IQR} 36-55] vs 43 [IQR 34-53]; P = 0.18) but was significantly higher for women with bilateral oophorectomy compared with those without (median 54 dB HL [IQR 44-61] vs 44 [IQR 34-53]; P = .03).

CONCLUSION

These data do not support a relationship between endogenous estrogen exposure and development of otosclerosis. Women with otosclerosis who had a history of pregnancy did not have significantly worse hearing at the time of diagnosis, suggesting that pregnancy is not associated with disease severity.

Otosclerosis and Measles: Do Measles Have a Role in Otosclerosis? A Review Article

Otosclerosis is a common cause of conductive hearing loss which is an autoimmune inflammatory disorder related to abnormal bone remodeling of the human otic capsule that has complex etiopathogenesis attributed to genetics, autoimmunity, viral infection, inflammation, hormonal factor, environmental factor, and disturbed bone metabolism. It has a prevalence of 0.3%-0.4% in Caucasians, which makes up 5-9% of all hearing loss and 18-22% of all conductive hearing loss. This review article aims to study the postulated role of sustained measles virus infection in the etiopathogenesis of otosclerosis, among others. A PubMed search of the related topic identified 97,990 articles. After we applied the inclusion and exclusion criteria, it was determined that 52 articles were relevant, which included 38 observational studies, 13 review articles, and a systematic review. Among them, 33 observational studies, 13 review articles and a systematic review spotted a positive association between persistent measles virus infection and otosclerosis. On the contrary, five observational studies reported no evidence of the association. The majority of the current literature supported the presence of the measles virus component in the otosclerotic stapes samples and its role in the etiopathogenesis of otosclerosis. Measles virus infection may have the amplitude to initiate a pathological process, which in the presence of other factors like autoimmunity and genes plays a significant role in causing otosclerosis. However, other studies have failed to show the presence of the measles virus component in otosclerotic stapes. So, more studies are needed to probe the role of persistent measles virus infection in the etiopathogenesis of otosclerosis.

Unfavourable prognostic factors in patients treated surgically for otosclerosis

Backgrounds: Otosclerosis is the cause of between 5% and 9% of all deafness cases and between 18% and 22% of conductive hearing loss cases. Neurosensory deafness develops in 30% of patients with otosclerosis.Aims/Objectives: The aim was to seek a correlation that would reflect the dependence of the results of middle ear surgery on the type of abnormalities atypical of otosclerosis but found during the stapedotomy surgery.Materials and Methods: The analysis included 140 patients who underwent surgery for otosclerosis. The hearing of all patients was assessed using an audiometric test.Results: In the assessment of changes in the mean bone conduction values, statistically significant differences between the reference group and the subgroup of patients on whom a myringoplasty was performed, as well as in patients with adhesions present in the middle ear spaces, were found only for the 500 Hz frequency.Conclusion and Significance: The removal of abnormalities, such as the loss of the eardrum (iatrogenic), changes to the lining and adhesions other than those typical of otosclerosis, restores middle ear mechanics after a stapedotomy on the inner ear and leads to a measurable improvement in mean bone conduction values.

Osteoprotegerin gene polymorphisms and otosclerosis: an additional genetic association study, multilocus interaction and meta-analysis

BACKGROUND

Otosclerosis (OTSC) is among the most common causes of a late-onset hearing loss in adults and is characterized by an abnormal bone growth in the otic capsule. Alteration in the osteoprotegerin (OPG) expression has been suggested in the implication of OTSC pathogenesis.

METHODS

A case-control association study of rs2228568, rs7844539, rs3102734 and rs2073618 single nucleotide polymorphisms (SNPs) in the OPG gene was performed in a Tunisian-North African population composed of 183 unrelated OTSC patients and 177 healthy subjects. In addition, a multilocus association and a meta-analysis of existing studies were conducted.

RESULTS

Rs3102734 (p = 0.013) and rs2073618 (p = 0.007) were significantly associated with OTSC, which were predominantly detected in females after multiple corrections. Among the OPG studied SNPs, the haplotypes A-A-C-G (p = 0.0001) and A-A-C-C (p = 0.0004) were significantly associated with OTSC in females. Multilocus association revealed that the SNPs: rs2073618 in OPG, rs1800472 in TGFβ1, rs39335, rs39350 and rs39374 in RELN, and rs494252 in chromosome 11 showed significant OTSC-associated alleles in Tunisian individuals. In addition, meta-analysis of the rs2073618 SNP in Tunisian, Indian and Italian populations revealed evidence of an association with OTSC (OR of 0.826, 95% CI [0.691-0.987], p = 0.035).

CONCLUSIONS

Our findings suggest that rs3102734 and rs2073618 variants are associated with OTSC in North African ethnic Tunisian population. Meta-analysis of the rs2073618 in three different ethnic population groups indicated an association with OTSC.

Effect of CO2 laser for the management of primary otosclerosis: A protocol for systematic review and meta-analysis

BACKGROUND

This study will explore the effect and safety of CO2 laser (COL) for the management of patients with primary otosclerosis (PO).

METHODS

The following electronic databases will be searched from inception to the present: PUBMED, EMBASE, The Cochrane Library, Web of Science, PsycINFO, Cumulative Index to Nursing and Allied Health Literature, Allied and Complementary Medicine Database, Chinese Biomedical Literature Database, VIP, WANGFANG, and China National Knowledge Infrastructure. No language limitation will be applied. All relevant randomized controlled trials using COL to treat patients with PO will be included. Two researchers will identify studies, collect data and evaluate the risk of bias of each included study independently. Any different views between 2 researchers will be resolved by a third researcher via discussion. Data analysis will be carried out using RevMan 5.3 software.

RESULTS

This study will evaluate the effect and safety of COL for the treatment of PO through hearing gain, tinnitus severity, incidence of intraoperative, health-related quality of life, other morbidities, and adverse events.

CONCLUSION

This study will provide evidence for the effect and safety of COL in patients with PO.

STUDY REGISTRATION NUMBER

INPLASY202040110.

GPER-1 and sex-hormone levels in patients with otosclerosis

OBJECTIVE

Otosclerosis is a widespread disease but the etiopathogenesis is still not fully understood. Hormonal factors especially estrogens are accused in recent years. The study aimed to evaluate the levels of G-protein associated membrane estrogen receptor-1 (GPER-1) and sex-hormones in patients with otosclerosis.

SUBJECT AND METHODS

The study included 60 people (30 otosclerosis patients, 30 control group). Serum sex-hormone (estradiol, progesterone, prolactin and total testosterone) and GPER-1 levels were measured in otosclerosis patients and compared with the normal population. For the otosclerosis group, air conduction and bone conduction thresholds and air-bone gaps were viewed from audiograms and the relationships between hearing and GPER-1 or sex-hormone levels were also investigated.

RESULTS

Sex-hormone levels were not different between the groups. GPER-1 level was significantly lower in the otosclerosis group [3.1353 (0.76-8.21) ng/mL] than the control group [5.4773 (0.96-20.31) ng/mL] (p =0.017). Differential diagnosis with ROC analysis for the GPER-1 level was also significant (p=0.017). GPER-1 level was significantly lower for the females than the males in the otosclerosis group (p=0.043). Serum estradiol, progesterone, and prolactin levels were significantly higher (p=0.02, p =0.029 and p=0.019 respectively) and the GPER-1 level was significantly lower (p= 0.04) in the female patients compared to the female controls. There was no statistically significant relationship between GPER-1 or sex-hormone levels and hearing parameters.

CONCLUSION

GPER-1 level was lower in the otosclerosis patients compared to healthy volunteers and also lower in females than males in the patient group. Female sex-hormone levels were higher and GPER-1 level was lower in the female patient group than the female control group. Neither GPER-1 nor sex-hormone levels were not predictive of hearing levels. These findings indicate that sex-hormones especially estrogen and GPER-1 might have a potential role in the etiopathogenesis of otosclerosis. This is the first study in the literature that investigates the GPER-1 values in otosclerosis.

Frequency-specific hearing results after stapes surgery for Chinese population otosclerosis with different degrees of hearing loss

Background: Frequency-specific hearing studies are important for predicting hearing results and the prognosis after stapes surgery, to prepare for the rehabilitation of frequency-specific hearing in patients with otosclerosis.Objectives: To evaluate outcomes of stapes surgery of Chinese otosclerosis patients with different degrees of hearing loss.Methods: We conducted a retrospective analysis of 213 otosclerosis patients who underwent stapes surgery in our hospital. Pre- and post-operative audiometric evaluation using conventional audiometry.Results: The post-op ABG was less than 20 dB in 94.52% of all cases after surgery. There was no statistical significance of the post-op ABG among different groups at all frequencies except extremely severe group (p < .05). There was a significant improvement of both AC and BC thresholds in post-op period and the most significant improvement was found in severe group. There were no serious post-op complications and no re-operations during the follow-up period.Conclusion: Stapes surgery is a suitable treatment option for otosclerosis with mild to extremely severe HL. The mild to moderate hearing loss groups had the most significant improvement of AC thresholds in the low frequency region, and the severe to extremely severe groups appeared in the high frequency region.

Predictors of hearing outcomes after stapes surgery in otosclerosis

Background: The current surgical treatment of otosclerosis is stapes surgery; however, few studies have reported the predictors of surgical outcomes.Aim/objective: This study aimed to investigate the prognostic predictors for postoperative hearing outcomes.Materials and methods: A total of 181 ears in 152 patients undergoing stapes surgery at a tertiary referral centre in Taiwan from 1996 to 2016 were retrospectively enrolled and preoperative and intraoperative parameters were obtained. Univariate and multivariate analyses were used to determine independent predictors of postoperative hearing outcomes. A regression model was also established. Hearing success was defined as a postoperative air-bone gap (ABG) ≤10 dB.Results: In univariate analysis, the absence of floating footplate during surgery (p = .003) and small preoperative ABG (p = .014) were associated with successful hearing outcomes. Multivariate logistic regression analysis further revealed the absence of floating footplate during surgery (p = .010) and small preoperative ABG (p = .015) remained independent predictors of postoperative hearing success.Conclusions and significance: Preoperative audiometric data and intraoperative finding may provide surgeons and patients with a better insight into surgical outcomes.

Changes to Hearing Levels Over the First Year After Stapes Surgery: An Analysis of 139 Patients

BACKGROUND

Stapes surgery is performed for hearing restoration in patients with otosclerosis. Results from stapes surgery are good, although a small proportion will have a persistent conductive hearing loss and will consider revision surgery. The timing of such surgery depends on expected changes to hearing thresholds during the postoperative period.

METHODS

We performed a retrospective case series analysis of a database of outcomes from stapes surgery performed between July 26, 2013 and March 11, 2016 at one center. Hearing outcomes over the year subsequent to surgery were recorded.

RESULTS

There was a significant improvement in hearing outcomes between the postoperative visit at 6 weeks (mean air-bone gap 6.0 dB) and the hearing outcome at 6 months (mean air-bone gap 3.3 dB) (p < 0.01). This improvement was maintained at 12 months (mean air-bone gap 3.1 dB), although there were individual patients whose hearing outcome improved or deteriorated during this period. Improvements in air conduction thresholds mirrored improvements in air-bone gap measurements.

CONCLUSION

Patients with an initial suboptimal or poor result after stapes surgery may observed improvement in their hearing thresholds in the year after surgery. These patients may have large preoperative air-bone gaps, and have a trend to have obliterated footplates. Revision surgery should not be considered until at least 6 months after primary surgery.

The Epidemiology of Deafness

Hearing loss is the most common sensory deficit worldwide. It affects ∼5% of the world population, impacts people of all ages, and exacts a significant personal and societal cost. This review presents epidemiological data on hearing loss. We discuss hereditary hearing loss, complex hearing loss with genetic and environmental factors, and hearing loss that is more clearly related to environment. We also discuss the disparity in hearing loss across the world, with more economically developed countries having overall lower rates of hearing loss compared with developing countries, and the opportunity to improve diagnosis, prevention, and treatment of this disorder.

Clinically important change in tinnitus sensation after stapedotomy

Background

When measuring the treatment effect in tinnitus with multi-item outcome instruments, it is crucial for both clinical and research purposes to take into consideration clinical importance of the outcome scores. The aim of the present study is to determine minimal important change (MIC) in tinnitus which is clinically meaningful to patients with otosclerosis.

Methods

The study population was 95 patients with otosclerosis, suffering from tinnitus. They completed the Tinnitus Functional Index before stapedotomy and 3 months after the surgery. The minimal important change was estimated with the Clinical Global Impression Scale as the external criterion (anchor). The mean change method and the receiver operating characteristic (ROC) method were used to determine minimal important change in tinnitus sensation.

Results

The improvement in tinnitus after stapedotomy was reported by 69.4% of the patients with otosclerosis. Minimal important change in tinnitus was estimated as reduction of 8.8 points in the Tinnitus Functional Index.

Conclusions

The anchor-based approach using an external criterion (anchor) allows to determine change in tinnitus sensation which is meaningful to patients after stapedotomy. The value of 8.8 points in Tinnitus Functional Index could be used as benchmark of stapedotomy effectiveness in otosclerosis patients suffering from tinnitus. Hearing difficulties comorbid with tinnitus could affect the perception of tinnitus change.

Variants affecting diverse domains of MEPE are associated with two distinct bone disorders, a craniofacial bone defect and otosclerosis

PURPOSE

To characterize new molecular factors implicated in a hereditary congenital facial paresis (HCFP) family and otosclerosis.

METHODS

We performed exome sequencing in a four-generation family presenting nonprogressive HCFP and mixed hearing loss (HL). MEPE was analyzed using either Sanger sequencing or molecular inversion probes combined with massive parallel sequencing in 89 otosclerosis families, 1604 unrelated affected subjects, and 1538 unscreened controls.

RESULTS

Exome sequencing in the HCFP family led to the identification of a rare segregating heterozygous frameshift variant p.(Gln425Lysfs*38) in MEPE. As the HL phenotype in this family resembled otosclerosis, we performed variant burden and variance components analyses in a large otosclerosis cohort and demonstrated that nonsense and frameshift MEPE variants were significantly enriched in affected subjects (p = 0.0006-0.0060).

CONCLUSION

MEPE exerts its function in bone homeostasis by two domains, an RGD and an acidic serine aspartate-rich MEPE-associated (ASARM) motif inhibiting respectively bone resorption and mineralization. All variants associated with otosclerosis are predicted to result in nonsense mediated decay or an ASARM-and-RGD-truncated MEPE. The HCFP variant is predicted to produce an ASARM-truncated MEPE with an intact RGD motif. This difference in effect on the protein corresponds with the presumed pathophysiology of both diseases, and provides a plausible molecular explanation for the distinct phenotypic outcome.

Pedigree Analysis and Audiological Investigations of Otosclerosis: An Extended Family Based Study

Background and Objectives

To analyse the audiometric profile and the pedigree of a large family with otosclerosis to understand the inheritance pattern and its implication in clinical management of the disease.

Subjects and Methods

Pedigree analysis was performed on the basis of family history and audiometric tests. Pure tone audiometry, tympanometry, and acoustic reflexes were evaluated for the family members. Audiometric analysis was also carried out for the individuals who have already underwent corrective surgery at the time of study.

Results

Out of 112 family members, 17 were affected individuals, and 11 of them were surgically confirmed. Hearing loss (HL) started unilaterally and progressed to bilateral form. Otosclerosis was presented in early 20’s in the first and second generations but it was delayed to mid-late 30’s in the fourth generation. An affected female was diagnosed with otosclerosis during her pregnancy. Though the disease was familial, a mother of four affected offspring in this family did not develop otosclerosis until she died at the age of 84.

Conclusions

The five-generation family, which was analysed in the present study, exhibited autosomal dominant inheritance of otosclerosis with reduced penetrance. Bilateral HL and pregnancy-aggravated otosclerosis were observed in this family. It was found for the first time that the age of onset of the disease delayed in the successive generations. The current study indicated the importance of detailed pedigree analysis for better clinical management of otosclerosis.

Understanding the causes and consequences of measles virus persistence

Measles is an acute systemic viral disease with initial amplification of infection in lymphoid tissue and subsequent spread over 10–14 days to multiple organs. Failure of the innate response to control initial measles virus (MeV) replication is associated with the ability of MeV to inhibit the induction of type I interferon and interferon-stimulated antiviral genes. Rather, the innate response is characterized by the expression of proteins regulated by nuclear factor kappa B and the inflammasome. With eventual development of the adaptive response, the rash appears with immune cell infiltration into sites of virus replication to initiate the clearance of infectious virus. However, MeV RNA is cleared much more slowly than recoverable infectious virus and remains present in lymphoid tissue for at least 6 months after infection. Persistence of viral RNA and protein suggests persistent low-level replication in lymphoid tissue that may facilitate maturation of the immune response, resulting in lifelong protection from reinfection, while persistence in other tissues (for example, the nervous system) may predispose to development of late disease such as subacute sclerosing panencephalitis. Further studies are needed to identify mechanisms of viral clearance and to understand the relationship between persistence and development of lifelong immunity.

Diagnostic performance of high resolution computed tomography in otosclerosis

AIM

To determine the sensitivity and specificity of high resolution computed tomography (HRCT) in the diagnosis of otosclerosis.

METHODS

A systematic literature review was undertaken to include Level I-III studies (Oxford Centre for Evidenced based Medicine) that utilised HRCT to detect histology confirmed otosclerosis. Quantitative synthesis was then performed.

RESULTS

Based on available level III literature, HRCT has a relatively low sensitivity of 58% (95%CI: 49.4-66.9), a high specificity, 95% (95%CI: 89.9-98.0) and a positive predictive value of 92% (95%CI: 84.1-95.8). HRCT is better at diagnosing the more prevalent fenestral form of otosclerosis but remains vulnerable to inframillimetre, retrofenestral and dense sclerotic lesions, despite the advent of more advanced CT scanners with improved collimation.

CONCLUSION

Whilst the diagnosis of otosclerosis remains largely clinical, HRCT remains the gold standard imaging of choice for the middle ear and serves as a useful adjunct to the clinician, helping to delineate extent of disease and exclude other causes.

Stapes surgery in Sweden: evaluation of a national-based register

The aim of the National Quality Registries is to monitor the outcome of healthcare given to patients. The Swedish Quality register for otosclerosis surgery is one of the nine official national registers for ear, nose and throat diseases in Sweden. Since 2004, surgical and audiological results and patient satisfaction scores have been systematically collected from a majority of the ear, nose and throat clinics performing stapes surgery in Sweden. The results of 1688 patients who underwent primary operations for otosclerosis were evaluated for 24 out of totally 26 clinics performing stapes surgery, between 2004 and 2010. The most common surgical technique reported was stapedotomy accomplished in an overnight stay. A majority of patients experienced improved hearing, and were satisfied with the preoperative counselling. Successful surgery, defined as an ABG closure ≤10 dB HL, was achieved in 69%, improvement in AC by ≥20 dB in 63% and BC not worsened by more than ≥5 dB in 93% of the patients. An overall low incidence of postoperative complications was reported. The outcome for ABG and BC was demonstrated to be independent of the number of operations performed by each clinic. An evaluation of the register and the results from the SQOS revealed that stapes surgery is a safe procedure with good hearing outcomes, low complication rates and a high rate of patient’s satisfaction on a national level.

The expression of tenascin-C and tenascin-W in human ossicles

The ossicles of the middle ear (the malleus, incus and stapes) transmit forces resulting from vibrations of the tympanic membrane to the cochlea where they are coded as sound. Hearing loss can result from diseases such as rheumatoid arthritis (RA) that affect the joints between the ossicles or degenerative processes like otosclerosis that lead to ankylosis of the footplate of the stapes in the oval window of the cochlea. In this study, immunohistochemistry was used to determine if the extracellular matrix glycoproteins tenascin-C or tenascin-W are expressed in the incudomalleolar and incudostapedial joints of ossicles dissected from human cadavers. Tenascin-C, which is expressed during inflammatory conditions including RA, was seen in the articular cartilage of the incudomalleolar joints and the head of the stapes. Tenascin-W, in contrast, was enriched in the annular ligament that anchors the footplate of the stapes into the oval window of the cochlea.

Mutations and altered expression of SERPINF1 in patients with familial otosclerosis

Otosclerosis is a relatively common heterogenous condition, characterized by abnormal bone remodelling in the otic capsule leading to fixation of the stapedial footplate and an associated conductive hearing loss. Although familial linkage and candidate gene association studies have been performed in recent years, little progress has been made in identifying disease-causing genes. Here, we used whole-exome sequencing in four families exhibiting dominantly inherited otosclerosis to identify 23 candidate variants (reduced to 9 after segregation analysis) for further investigation in a secondary cohort of 84 familial cases. Multiple mutations were found in the SERPINF1 (Serpin Peptidase Inhibitor, Clade F) gene which encodes PEDF (pigment epithelium-derived factor), a potent inhibitor of angiogenesis and known regulator of bone density. Six rare heterozygous SERPINF1 variants were found in seven patients in our familial otosclerosis cohort; three are missense mutations predicted to be deleterious to protein function. The other three variants are all located in the 5′-untranslated region (UTR) of an alternative spliced transcript SERPINF1-012. RNA-seq analysis demonstrated that this is the major SERPINF1 transcript in human stapes bone. Analysis of stapes from two patients with the 5′-UTR mutations showed that they had reduced expression of SERPINF1-012. All three 5′-UTR mutations are predicted to occur within transcription factor binding sites and reporter gene assays confirmed that they affect gene expression levels. Furthermore, RT-qPCR analysis of stapes bone cDNA showed that SERPINF1-012 expression is reduced in otosclerosis patients with and without SERPINF1 mutations, suggesting that it may be a common pathogenic pathway in the disease.

Acquired Hearing Loss in Children

Hearing loss is the most common congenital sensory impairment. According to National Health and Nutrition Examination Survey data from 2001 to 2008, 20.3% of subjects aged greater than or equal to 12 had unilateral or bilateral hearing loss. The World Health Organization notes that, worldwide, there are 360 million people with disabling hearing loss, with 50% preventable. Although many hearing losses are acquired, many others are manifestations of preexisting conditions. The purpose of a pediatric hearing evaluation is to identify the degree and type of hearing loss and etiology and to outline a comprehensive strategy that supports language and social development and communication.

Surgical treatment of hearing loss when otosclerosis coexists with superior semicircular canal dehiscence syndrome

OBJECTIVE

Document a case of bilateral otosclerosis with coexisting bilateral superior semicircular canal dehiscence syndrome and the treatment of hearing loss in this setting.

PATIENT

A 33-year-old woman presented with bilateral mixed hearing loss; worse in the left ear. This was gradual in onset, and she denied dizziness. Computerized tomographic scan revealed fenestral otosclerosis and a large dehiscence of the superior semicircular canal bilaterally. She declined amplification.

INTERVENTION

Sequential laser-assisted stapedotomy with insertion of a Kurz titanium CliP Piston prosthesis.

MAIN OUTCOME MEASURE

Comparison of audiovestibular symptoms, hearing thresholds, and neurodiagnostic testing results preoperatively and postoperatively.

RESULTS

Hearing improved bilaterally with closure of the air-bone gaps at most frequencies, and she has not had permanent vestibular symptoms. Postoperative follow-up time is 37 months for the left ear and 13 months for the right ear.

CONCLUSION

When otosclerosis and superior semicircular canal dehiscence syndrome coexist and hearing loss is the dominant symptom, stapes surgery can be effective for improving hearing without permanent vestibular symptoms.

Genetic association and altered gene expression of osteoprotegerin in otosclerosis patients

Otosclerosis (OTSC) is a late-onset hearing disorder characterized by increased bone turnover in the otic capsule. Disturbed osteoprotegerin expression has been found in the otosclerotic foci which may have an important role in the pathogenesis of OTSC. To identify the genetic risk factors, we sequenced the coding region and exon-intron boundaries of the OPG gene in 254 OTSC patients and 262 controls. Sequence analysis identified five known polymorphisms c.9C>G, c.30+15C>T, c.400+4C>T, c.768A>G, and c.817+8A>C. Testing of these SNPs revealed sex specific association with c.9C>G in males and c.30+15C>T in females after multiple correction. Furthermore, meta-analysis provided evidence of association of the c.9C>G polymorphism with OTSC. In secondary analysis, we investigated the mRNA expression of OPG and associated genes RANK and RANKL in otosclerotic tissues compared to controls. Expression analysis revealed significantly missing/reduced OPG expression only in otosclerotic tissues. However, the signal sequence polymorphism c.9C>G has shown no effect on OPG mRNA expression. In conclusion, our results suggest that the risk of OTSC is influenced by variations in the OPG gene along with other factors which might regulate its altered expression in otosclerotic tissues. Further research is warranted to elucidate the mechanisms underlying these observations.

Prevalence of 'surfer's ear' in Cornish surfers

OBJECTIVES

To establish the prevalence of external auditory canal exostosis ('surfer's ear') in Cornish surfers and investigate the potential impact on healthcare.

METHOD

A total of 105 surfers were interviewed and otologically assessed on popular Cornish beaches. The degree of exostosis was graded as mild, moderate or severe.

RESULTS

The prevalence of external auditory canal exostosis was 63.81 per cent (33.33 per cent mild, 18.10 per cent moderate and 12.38 per cent severe). The degree of exostosis showed a significant correlation with absolute cold-water exposure time. However, there was individual variation in susceptibility to external auditory canal exostosis; 12 per cent of surfers with excessive cold-water exposure showed no exostosis. Regression analysis of surgical operations performed at the Royal Cornwall Hospital for exostosis over the last 13 years revealed an average increase of 1.23 operations per year, with an average of 13 cases per year over the last 9 years.

CONCLUSION

Exostosis of the external auditory canal is common in Cornish surfers. There appears to be individual variation in terms of susceptibility to this condition. The possible reasons for this are discussed. The increase in the technically difficult surgical operations performed for exostosis is likely to have implications for health resources in the future.

The role of genetic factors for hearing deterioration across 20 years: a twin study

BACKGROUND

Hearing deterioration at advanced ages is associated with environmental exposures (eg, to noise and solvents) and genetic influences may also be important. Little is known about the role of genetic influences on hearing when evaluated longitudinally. We sought to investigate longitudinal hearing loss in a cohort of adult male twins to evaluate the importance of genetic and environmental factors for hearing deterioration over time.

METHODS

Hearing using conventional clinical audiometry was assessed in 583 male twins (128 monozygotic twin pairs and 111 dizygotic twin pairs) aged 34-79 at baseline and again two decades later. The hearing thresholds at two time points were compared at each frequency and in two different frequency regions. Genetic analyses were based on structural equation models. Bivariate Cholesky decomposition was used for longitudinal analysis.

RESULTS

The prevalence of hearing loss increased over time in better and worse ear. The hearing threshold shift was more pronounced in the high-frequency region, especially at 8000 Hz. Genetic influences were moderate (heritability: 53%-65%) for pure-tone averages at both lower and higher frequencies, and were of equal magnitude at baseline and follow-up. In contrast, environmental influences were of substantial importance (55%-88%) for rate of change of the hearing threshold over the 18-year period.

CONCLUSIONS

Genetic factors are of considerable importance for level of hearing acuity, but environmental factors are more important for rate of change over an 18-year period.

Experimental in vitro infection of rat osteoblasts with measles virus stimulates osteogenic differentiation

In this work we characterized the infection of a primary culture of rat osteoblastic lineage cells (OBCs) with measles virus (MeV) and the effect of infection on cell differentiation and maturation. Infection of OBCs with MeV led to high titers of infectivity released early after infection. Also, analysis of mRNAs corresponding to osteogenic differentiation markers like alkaline phosphatase (ALP), bone sialo-protein (BSP) and bone morphogenetic proteins (BMPs) 1-4-5-7 in OBCs revealed higher values (2-75-fold of increment) for infected cells in comparison with uninfected controls. Differentiation of OBCs in osteogenic medium prior to infection influenced the level of stimulation induced by MeV. Furthermore, treatment of OBCs with Ly294002, a PI3K/AKT inhibitor, increased viral titers, whereas treatment with 10μM or 100μM ATPγS diminished MeV multiplication. In addition, increments of osteogenic differentiation markers induced by MeV infection were not modified either by treatment with Ly294002 or ATPγS. These data provide the first evidence demonstrating that MeV can infect osteoblasts in vitro leading to osteoblastic differentiation, a key feature in bone pathogenic processes like otosclerosis.

The role of imaging in the diagnosis and management of otosclerosis

OBJECTIVE

To examine the evidence for the role of radiologic imaging in the diagnosis and management of otosclerosis.

DATA SOURCES

A review of contemporary (1990 to present) English medical literature via MedLine using the terms imaging, otosclerosis, otospongiosis, stapes surgery, computed tomography, magnetic resonance, CT, and MRI was performed.

STUDY SELECTION

Abstracts were reviewed independently by 2 authors and relevant articles were then evaluated. Exclusion criteria included editorials, non-English language, comments, and letters.

DATA EXTRACTION

Level of evidence was assigned in accordance with the Oxford Centre for Evidence-based Medicine guidance (Levels I-V).

RESULTS

Thirty-seven articles met the inclusion criteria, of which, 11 were of Level III, 22 of Level IV, and 4 of level V evidence. High-resolution computed tomography (CT) of the temporal bones is the imaging technique of choice in the diagnosis of otosclerosis with newer multidetector scanners demonstrating a sensitivity and specificity in excess of 90%. There is Level III evidence that CT densitometry and extent of disease on CT correlates with hearing thresholds. Extensive and multifocal disease on CT has a poorer prognosis (Level III/IV). The potential use of CT in staging classifications, surgical planning, predicting surgical outcomes and risk of complications has also been described and evaluated.

CONCLUSION

This systematic review indicates that imaging has a useful role in both the diagnosis and management of otosclerosis, supported principally by Level III/IV evidence.

Contribution of Vestibular-Evoked Myogenic Potential (VEMP) testing in the assessment and the differential diagnosis of otosclerosis

Background

The aim of this prospective clinical study was to evaluate the clinical importance of Vestibular-Evoked Myogenic Potentials (VEMPs) in the assessment and differential diagnosis of otosclerosis and otologic diseases characterized by “pseudo-conductive” components. We also investigated the clinical appearance of balance disorders in patients with otosclerosis by correlating VEMP results with the findings of caloric testing and pure tone audiometry(PTA).

Material/Methods

Air-conducted(AC) 4-PTA, bone-conducted(BC) 4-PTA, air-bone Gap(ABG), AC, BC tone burst evoked VEMP, and calorics were measured preoperatively in 126 otosclerotic ears.

Results

The response rate of the AC-VEMPs and BC-VEMPs was 29.36% and 44.03%, respectively. Statistical differences were found between the means of ABG, AC 4-PTA, and BC 4-PTA in the otosclerotic ears in relation to AC-VEMP elicitability. About one-third of patients presented with disequilibrium. A statistically significant interaction was found between calorics and dizziness in relation to PTA thresholds. No relationship was found between calorics and dizziness with VEMPs responses.

Conclusions

AC and BC VEMPs can be elicited in ears with otosclerosis. AC-VEMP is more vulnerable to conductive hearing loss. Evaluation of AC-VEMP thresholds can be added in the diagnostic work-up of otosclerosis in case of doubt, enhancing differential diagnosis in patients with air-bone gaps. Otosclerosis is not a cause of canal paresis or vertigo.

Exclusion of TNFRSF11B as Candidate Gene for Otosclerosis in Campania Population

The etiology of otosclerosis is unknown. The etiopathogenesis of otosclerosis seems similar to that occurring in Paget's disease of bone, for which mutations or polymorphisms in several genes have been identified. Among these, TNFRSF11B gene encoding the osteoprotegerin is produced at high levels in the normal inner ear and at low level in active otosclerotic stapes footplates. The aim of this work was to verify the presence of a correlation between the rs2073618 (N3K) polymorphism in the TNFRSF11B gene and otosclerosis. Mutational screening in the TNFRSF11B gene was performed by direct sequencing. SNPs analysis was performed by PCR and by specific restriction enzyme assay with HpaI. The significance of the association was analyzed by statistical specific software. No causative mutation has been identified but the data suggested a strong correlation between the rs2073618 (N3K) polymorphism and otosclerosis. This correlation, however, has been excluded in a case-control study. This study excluded the association between the N3K polymorphism and otosclerosis in Campania region population.

An introduction of genetics in otosclerosis: a systematic review

OBJECTIVE

To present an easy to read systematic review concerning the genetic etiology of otosclerosis to help health care providers in counseling otosclerosis patients more accurately.

DATA SOURCES

PubMed, Embase, CINAHL, and the Cochrane Library.

REVIEW METHODS

Studies on the genetic etiology of otosclerosis were selected. Association studies and family-based studies were included for further review. After quality assessment (risk of bias), data were extracted from the included studies. When available, odds ratios were presented. In case of corresponding genetic anomalies between the studies, it was the aim to combine results.

RESULTS

The number of available studies with low risk of bias is limited to 2 association studies and 1 family-based study. These high-quality studies show that otosclerosis in Japanese patients is not linked to the NOG gene and that a polymorphism in the Sp1 binding site located on the COL1A1 gene is associated with otosclerosis as well as OTSC1. Association and family-based studies with moderate risk of bias show a statistically significant association with the ACE gene, AGT gene, OTSC2, RELN gene, TGFB1 gene, 11q13.1, OTSC2, OTSC5, OTSC8, and OTSC10. These results may be spurious associations due to their bias and low statistical power.

CONCLUSION

The present systematic review shows that there is scattered evidence of limited quality and a lack of replication studies. It is not possible to point out 1 or more responsible genes, which play a key role within the genetic pathophysiologic mechanism of otosclerosis.

Otosclerosis and vitamin D receptor gene polymorphism

OBJECTIVE

The possible genetic relationship between otosclerosis and Vitamin D Receptor (VDR) gene polymorphism is uncertain. The aim of this study is to assess association between otosclerosis and VDR gene polymorphisms.

STUDY DESIGN

Case-control Studies.

SETTING

Tertiary referral center.

SUBJECTS AND METHODS

Clinical diagnosis of stapes fixation was based on otoscopic, audiometric, tympanometric and surgical findings. We identified 25 eligible patient and 60 controls to investigate the association of the VDR gene polymorphisms FokI, BsmI, ApaI, and Taq I with otosclerosis. The patient and control DNA was genotyped for; VDR Bsm I (rs1544410), VDR Apa I (rs7975232), VDR Taq I (rs731236) and VDR Fok I (rs2228570) gene. Primer, simple probe sequences was genotyped by RT-PCR restriction fragment length polymorphism.

RESULTS

There was a statistically significant association between VDR gene and otosclerosis in polymorphism Taq I, Apa I and Bsm I. There was no significant association between VDR gene and otosclerosis in polymorphism Foq I.

CONCLUSION

Three polymorphisms (Taq I, Apa I and Bsm I) in the VDR gene appear to be associated to susceptibility to otosclerosis disorder with otosclerosis patients.

No evidence for the expression of renin-angiotensin-aldosterone system in otosclerotic stapes footplates

INTRODUCTION

Recent studies have reported genetic associations between with single nucleotide polymorphism (SNP) of the several genes of the renin-angiotensin-aldosterone (RAA) system in otosclerosis without the confirmation of RAA system expression in human stapes footplates. There are conflicting results. These results are conflicting because RAA system expression has been attributed exclusively to neural, vascular, and renal tissues, exclusively.

MATERIALS AND METHODS

Ankylotic stapes footplates (n = 20), cortical bone fragments (n = 10), and human kidney tissue specimens (n = 10) were processed to hematoxylin-eosin (HE) staining and RAA system-specific immunofluorescent assay (IFA), respectively.

RESULTS

Histologic diagnosis of otosclerosis was established in all ankylotic stapes footplates. Histologically active- (n = 13) and inactive (n = 7) foci of otosclerosis were consequently characterized by negative immunoreactions for renin, angiotensin converting enzyme (ACE), angiotensin-II (AT-II), and angiotensin-II receptor (AT-IIR), consequently. In cortical bones, a considerable RAA system expression was observed confirmed in the perivascular bone marrow progenitor cells. Kidney specimens, applied as positive controls, showed intense RAA system-specific immunoreactions.

CONCLUSION

Concerning current observations, the 4 studied members of RAA system that did not display active expression were not expressed at protein level in otosclerotic stapes footplates. This phenomenon was independent from the histologic activity of otosclerosis. Between these conditions, the etiologic role of RAA system is questionable in the pathogenesis of otosclerosis.

Mutation analysis of Netrin 1 and HMX3 genes in patients with superior semicircular canal dehiscence syndrome

CONCLUSION

In spite of its absence in the control population, there is questionable evidence for the alteration c.114C->T in the HMX3 gene being implicated in the development of superior semicircular canal dehiscence (SSCD). However, the concept of a complex disease is valid for SSCD and a possible molecular origin can neither be confirmed nor excluded by the results of this study.

OBJECTIVES

SSCD was first described in 1998 by Minor et al. While the etiology is not clear, findings from both temporal bone CT and histologic studies suggest a congenital or developmental origin. In recent years, a couple of genes regulating inner ear morphogenesis have been described. Specifically, Netrin-1 and HMX3 have been shown to be critically involved in the formation of the SCC. Molecular alterations in these two genes might lead to a disturbed development of this canal and might represent an explanation for SSCD.

METHODS

DNA was extracted from whole blood of 15 patients with SSCD. The coding sequences of Netrin-1 and HMX3 were amplified by PCR and sequenced.

RESULTS

One sequence alteration, heterozygous c.114C->T (conservative change without alteration of amino acid) in exon 1 of HMX3, was detected in 2 of 15 patients but not in 300 control chromosomes. The study was supported in part by the Emilia-Guggenheim-Schnurr-Foundation, Basel, Switzerland.

Mutations in the NOG gene are commonly found in congenital stapes ankylosis with symphalangism, but not in otosclerosis

Human noggin (NOG) is a responsible gene for multiple synostosis syndrome (SYNS1) and proximal symphalangism (SYM1), two conditions that are recently known to be within a wider range of clinical manifestations of stapes ankylosis with symphalangism. This study was performed to determine the range of phenotype caused by NOG mutations, using Japanese patients with various phenotypes including sporadic inherited SYM1, dominantly inherited SYM1, stapes ankylosis with broad thumb and toes (Teunissen and Cremer syndrome). In addition, 33 patients with typical otosclerosis (without symphalangism) were studied. Direct sequencing analysis disclosed three novel mutations of the NOG gene in three SYM1 families. None of the otosclerosis patients without symphalangism had NOG mutations, indicating that NOG mutations may be restrictively found within patients with various skeletal abnormalities. These results together with the literature review indicated that there are no clear genotype–phenotype correlations for NOG mutations. With regard to surgical outcome, most of the patients in these three families with NOG mutations showed remarkable air–bone gap recovery after stapes surgery. Molecular genetic testing is useful to differentiate syndromic stapes ankylosis from otosclerosis, and even mild skeletal anomalies can be a diagnostic indicator of NOG-associated disease.