The genetic nature of sensorineural hearing loss (SNHL) has so far been studied for many ethnic groups in various parts of the world. The single-nucleotide guanine deletion (35delG) of the GJB2 gene coding for connexin 26 was shown to be the main genetic cause of autosomal recessive deafness among Europeans. Here we present the results of the first study of GJB2 and three mitochondrial mutations among two groups of Belarusian inhabitants: native people with normal hearing (757 persons) and 391 young patients with non-syndromic SNHL. We have found an extremely high carrier frequency of 35delG GJB2 mutation in Belarus −5.7%. This point deletion has also been detected in 53% of the patients with SNHL. The 312del14 GJB2 was the second most common mutation in the Belarus patient cohort. Mitochondrial A1555G mt-RNR1 substitution was found in two SNHL patients (0.55%) but none were found in the population cohort. No individuals carried the A7445G mutation of mitochondrial mt-TS1. G7444A as well as T961G substitutions were detected in mitochondrial mt-RNR1 at a rate of about 1% both in the patient and population cohorts. A possible reason for Belarusians having the highest mutation carrier frequency in Europe 35delG is discussed.
Background:The splice site nucleotide substitution IVS1+1G>A in the non-coding part of the GJB2 gene is one of the recessive pathogenic mutations causing nonsyndromic sensorineural hearing loss (NSHL). We present here the results of a study of IVS1+1G>A among Belarusian patients with NSHL as well as among Belarusian controls with normal hearing. Material and methods:The PCR-RFLP method was used for genotyping. All tested patients were subdivided into three groups: those who carried only one mutant allele of GJB2 exon 2 (group A, 28 patients), those with no mutation of GJB2 exon 2 (group B, 150 patients), and patients with two mutations previously detected in the second exon of GJB2 or with one mutation and a large GJB6 deletion ∆D13S1830 (group C, 223 patients). Also 300 Belarusian people with normal hearing were screened for IVS1+1G>A.Results: We detected 7 patients with IVS1+1G>A mutation in the A group, which explained hearing loss in 25% of this deafness cohort. None of the B or C group patients carried the IVS1+1G>A mutation. We also did not find any IVS1+1G>A mutation carriers among the 300 Belarusian control people with normal hearing.Conclusions: IVS1+1G>A is the third-most frequent mutation (after 35delG and 312del14) among Belarusian patients with NSHL; its rate is 1.8% for the patient cohort we studied and the population frequency is below 0.33%. We propose to include the IVS1+1G>A mutation into a laboratory screening protocol for those patients with NSHL that carry one mutant allele of GJB2 exon 2.
METHOD: Retrospective chart review in the biggest pediatric hospital in Lisbon (Portugal). Between 2003 and 2008, 254 pediatric patients were codified as tympanoplasty (ICD-9). Only 93 were included in this study: simple perforation, children younger than 15y, and follow-up longer than 1y. Reviewed factors included: gender, age, disease in the contralateral ear, local and size of perforation, and pre-operative tympanometric volume. The Chi-square and T student test were used for comparing the variables between the failure and success group. RESULTS: The overall failure rate of tympanoplasty was 29% (22 reperforations, three otitis with effusion, two atelectasis). The mean age of the failure group was 9y compared with 11y in the success group (pϭ0.28). The failure rate was 34% in boys compared with 26% in girls (rϭ0.1), and 50% in cases with anterior perforation compared with 26% in central perforation. The failure rate was similar when we compared the group with normal and the group with abnormal contralateral ear (rϭ0.08). When we established a cut-off value of 3.5cc in the tympanometric volume, the failure rate was 27% (for volumes greater than 3.5 cc) compared with 42% (for volumes under 3.5cc). In the group with 4-7 year olds (Nϭ21), the failure rate was 43% compared with 26% in the group with 8-15 year olds (Nϭ72). In the former, the tympanometric volume was 3.42 cc in the success group and 2.56cc in the failure group (pϭ0.13). CONCLUSION:The gender (boys), children younger than eight years old, the anterior perforations, and the tympanometric volume less than 3.5cc seems to be important predictive factors of failure in tympanoplasty in children.
Objectives -to compare the functional state of middle ear in adults in case of various pathology of nasal cavity, paranasal sinuses and throat. Material and methods. In 2018-2019 period, 151 patient, aged from 16 to 70 years, was examined by acoustic impedancemetry. The patients reported the subjective satisfactory state of the acoustic organ, but had a pathology of the upper respiratory tract. Results. In the groups, there were no significant differences associated with gender. Most of the patients were of working age. In all study groups, the impaired function of the auditory tube, with various intensity, was registered, although the patients had no hearing complaints. At the same time, the acumetry and tonal threshold audiometry data indicated the normal acuity of hearing. Conclusion. Acute and chronic sinusitis was the most frequent risk factor for middle ear ventilation disorder. A quarter of patients with acute sinusitis, without otological complaints, had type B and C tympanograms. 93.7% of patients, who had undergone the surgical correction of the deviated nasal septum, did not have a middle ear ventilation disorder. Surgical intervention in the nasal cavity and oropharynx leads to a transient dysfunction of the auditory tube, but does not require special treatment due to self-recovery.
Objectives to analyse the risk factors for developing effusion in the tympanic cavity in adults. Material and methods. We examined patients who were treated for otitis media with effusion (n=51) aged 18-70 years in the ENT department of the 11 Minsk City Clinical Hospital and the Gomel Regional Clinical Hospital during the 2018-2020 years. Results. The acute otitis media with effusion was significantly prevailing in patients of the age group 31-40 years, the chronic form predominated in people of 51-60 years old, and in all analyzed groups women dominated. In 81% of chronic inflammation of the paranasal sinuses the chronic form of otitis media with effusion prevails. Conclusion. The most frequent risk factors for the formation of the tympanic exudate were inflammatory diseases of the paranasal sinuses, pathology of the nasal cavity, predominantly female sex of working age. According to the research, it was reliably proved that smoking and rural or urban residence were not a risk factor for the formation of tympanic effusion.
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