Frequency of Usher gene mutations in non-syndromic hearing loss: higher variability of the Usher phenotype

Balance Control Impairments in Usher Syndrome

OBJECTIVES

To explore postural disability in Usher Syndrome (USH) patients using temporal posturographic analysis to better elucidate sensory compensation strategies of deafblind patients for posture control and correlate the Activities-specific Balance Confidence (ABC) scale with posturographic variables.

DESIGN

Thirty-four genetically confirmed USH patients (11 USH1, 21 USH2, 2 USH 4) from the Otolaryngology Outpatient Clinic and 35 controls were prospectively studied using both classical and wavelet temporal analysis of center of pressure (CoP) under different visual conditions on static and dynamic platforms. The functional impact of balance was assessed with the ABC scale. Classical data in the spatial domain, Sensorial Organization Test, and frequency analysis of the CoP were analyzed.

RESULTS

On unstable surfaces, USH1 had greater CoP surface area with eyes open (38.51 ± 68.67) and closed (28.14 ± 31.64) versus controls (3.31 ± 4.60), p < 0.001 and (7.37 ± 7.91), p < 0.001, respectively. On an unstable platform, USH consistently showed increased postural sway, with elevated angular velocity versus controls with eyes open (USH1 [44.94 ± 62.54]; USH2 [55.64 ± 38.61]; controls [13.4 ± 8.57]) (p = 0.003; p < 0.001) and closed (USH1 [60.36 ± 49.85], USH2 [57.62 ± 42.36]; controls [27.31 ± 19.79]) (p = 0.002; p = 0.042). USH visual impairment appears to be the primary factor influencing postural deficits, with a statistically significant difference observed in the visual Sensorial Organization Test ratio for USH1 (80.73 ± 40.07, p = 0.04) and a highly significant difference for USH2 (75.48 ± 31.67, p < 0.001) versus controls (100). In contrast, vestibular (p = 0.08) and somatosensory (p = 0.537) factors did not reach statistical significance. USH exhibited lower visual dependence than controls (30.31 ± 30.08) (USH1 [6 ± 11.46], p = 0.004; USH2 [8 ± 14.15], p = 0.005). The postural instability index, that corresponds to the ratio of spectral power index and canceling time, differentiated USH from controls on unstable surface with eyes open USH1 (3.33 ± 1.85) p < 0.001; USH2 (3.87 ± 1.05) p < 0.002; controls (1.91 ± 0.85) and closed USH1 (3.91 ± 1.65) p = 0.005; USH2 (3.92 ± 1.05) p = 0.045; controls (2.74 ± 1.27), but not USH1 from USH2. The canceling time in the anteroposterior direction in lower zone distinguished USH subtypes on stable surface with optokinetic USH1 (0.88 ± 1.03), USH2 (0.29 ± 0.23), p = 0.026 and on unstable surface with eyes open USH1 (0.56 ± 1.26), USH2 (0.072 ± 0.09), p = 0.036. ABC scale could distinguish between USH patients and controls, but not between USH subtypes and it correlated with CoP surface area on unstable surface with eyes open only in USH1(ρ = 0.714, p = 0.047).

CONCLUSIONS

USH patients, particularly USH1, exhibited poorer balance control than controls on unstable platform with eyes open and appeared to rely more on proprioceptive information while suppressing visual input. USH2 seems to use different multisensory balance strategies that do not align as well with the ABC scale. The advanced analysis provided insights into sensory compensation strategies in USH subtypes.

Vestibulo-ocular reflex dynamics with head-impulses discriminates Usher patients type 1 and 2

Usher Syndrome classification takes into account the absence of vestibular function but its correlation with genotype is not well characterized. We intend to investigate whether video Head Impulse Test (vHIT) is useful in screening and to differentiate Usher Syndrome types. 29 Usher patients (USH) with a genetically confirmed diagnosis and 30 healthy controls were studied with vHIT and dizziness handicap inventory questionnaire (DHI). Statistical significant differences between USH1, USH2 and controls were found in the vestibulo-ocular-reflex (VOR) gain of all SCCs, with USH1 patients consistently presenting smaller gains. VOR gain of the right lateral SCC could discriminate controls from USH1, and USH2 from USH1 with an overall diagnostic accuracy of 90%. USH1 DHI correlated with VOR (ρ = - 0,971, p = 0.001). Occurrence rate of covert and overt lateral semicircular canals refixation saccades (RS) was significantly different between groups, being higher in USH1 patients (p < 0.001). USH1 peak velocity of covert and overt saccades was higher for lateral semicircular canals (p < 0.05 and p = 0.001) compared with USH2 and controls. Covert saccades occurrence rate for horizontal SCCs could discriminate USH1 from USH2 patients and controls with a diagnostic accuracy of 85%. vHIT is a fast and non-invasive instrument which allowed us to screen and distinguish Usher patients from controls with a high precision. Importantly, its use allowed further discrimination between USH1 from USH2 groups. Moreover, VOR gain seems to correlate with vertigo-related quality of life in more severe phenotypes.

Spectrum of variants associated with inherited retinal dystrophies in Northeast Mexico

BACKGROUND

Inherited retinal dystrophies are hereditary diseases which have in common the progressive degeneration of photoreceptors. They are a group of diseases with clinical, genetic, and allelic heterogeneity. There is limited information regarding the genetic landscape of inherited retinal diseases in Mexico, therefore, the present study was conducted in the northeast region of the country.

METHODS

Patients with inherited retinal dystrophies were included. A complete history, full ophthalmological and medical genetics evaluations, and genetic analysis through a targeted NGS panel for inherited retinal dystrophies comprising at least 293 genes were undertaken.

RESULTS

A total of 126 patients were included. Cases were solved in 74.6% of the study's population. Retinitis pigmentosa accounted for the most found inherited retinal disease. Ninety-nine causal variants were found, being USH2A and ABCA4 the most affected genes (26 and 15 cases, respectively).

CONCLUSIONS

The present study documents the most prevalent causative genes in IRDs, as USH2A, in northeastern Mexico. This contrasts with previous reports of IRDs in other zones of the country. Further studies, targeting previously unstudied populations in Mexico are important to document the genetic background of inherited retinal dystrophies in the country.

Preliminary investigation of the diagnosis and gene function of deep learning PTPN11 gene mutation syndrome deafness

Syndromic deafness caused by PTPN11 gene mutation has gradually come into the public's view. In the past, many people did not understand its application mechanism and role and only focused on non-syndromic deafness, so the research on syndromic deafness is not in-depth and there is a large degree of lack of research in this area. In order to let the public know more about the diagnosis and gene function of deafness caused by PTPN11 gene mutation syndrome, this paper used deep learning technology to study the diagnosis and gene function of deafness caused by syndrome with the concept of intelligent medical treatment, and finally drew a feasible conclusion. This paper provided a theoretical and practical basis for the diagnosis of deafness caused by PTPN11 gene mutation syndrome and the study of gene function. This paper made a retrospective analysis of the clinical data of 85 deaf children who visited Hunan Children's Hospital,P.R. China from January 2020 to December 2021. The conclusion were as follows: Children aged 1-6 years old had multiple syndrome deafness, while children under 1 year old and children aged 6-12 years old had relatively low probability of complex deafness; girls were not easy to have comprehensive deafness, but there was no specific basis to prove that the occurrence of comprehensive deafness was necessarily related to gender; the hearing loss of patients with Noonan Syndrome was mainly characterized by moderate and severe damage and abnormal inner ear and auditory nerve; most of the mutation genes in children were located in Exon1 and Exon3, with a total probability of 57.65%. In the course of the experiment, it was found that deep learning was effective in the diagnosis of deafness with PTPN11 gene mutation syndrome. This technology could be applied to medical diagnosis to facilitate the diagnosis and treatment of more patients with deafness with syndrome. Intelligent medical treatment was also becoming a hot topic nowadays. By using this concept to analyze and study the pathological characteristics of deafness caused by PTPN11 gene mutation syndrome, it not only promoted patients to find diseases in time, but also helped doctors to diagnose and treat such diseases, which was of great significance to patients and doctors. The study of PTPN11 gene mutation syndrome deafness was also of great significance in genetics. The analysis of its genes not only enriched the gene pool, but also provided reference for future research.

Genetic etiology of non-syndromic hearing loss in Europe

Hearing impairment not etiologically associated with clinical signs in other organs (non-syndromic) is genetically heterogeneous, so that over 120 genes are currently known to be involved. The frequency of mutations in each gene and the most frequent mutations vary throughout populations. Here we review the genetic etiology of non-syndromic hearing impairment (NSHI) in Europe. Over the years, epidemiological data were scarce because of the large number of involved genes, whose screening was not cost-effective until implementation of massively parallel DNA sequencing. In Europe, the most common form of autosomal recessive NSHI is DFNB1, which accounts for 11-57% of the cases. Mutations in STRC account for 16% of the recessive cases, and only a few more (MYO15A, MYO7A, LOXHD1, USH2A, TMPRSS3, CDH23, TMC1, OTOF, OTOA, SLC26A4, ADGRV1 and TECTA) have contributions higher than 2%. As regards autosomal-dominant NSHI, DFNA22 (MYO6) and DFNA8/12 (TECTA) represent the most common forms, accounting for 21% and 18% of elucidated cases, respectively. The contribution of ACTG1 and WFS1 drops to 9% in both cases, followed by POU4F3 (6.5%), MYO7A (5%), MYH14 and COL11A2 (4% each). Four additional genes contribute 2.5% each one (MITF, KCNQ4, EYA4, SOX10) and the remaining are residually represented. X-linked hearing loss and maternally-inherited NSHI have minor contributions in most countries. Further knowledge on the genetic epidemiology of NSHI in Europe needs a standardization of the experimental approaches and a stratification of the results according to clinical features, familial history and patterns of inheritance, to facilitate comparison between studies.

Usher Syndrome

Usher syndrome (USH) is the most common genetic condition responsible for combined loss of hearing and vision. Balance disorders and bilateral vestibular areflexia are also observed in some cases. The syndrome was first described by Albrecht von Graefe in 1858, but later named by Charles Usher, who presented a large number of cases with hearing loss and retinopathy in 1914. USH has been grouped into three main clinical types: 1, 2, and 3, which are caused by mutations in different genes and are further divided into different subtypes. To date, nine causative genes have been identified and confirmed as responsible for the syndrome when mutated: MYO7A, USH1C, CDH23, PCDH15, and USH1G (SANS) for Usher type 1; USH2A, ADGRV1, and WHRN for Usher type 2; CLRN1 for Usher type 3. USH is inherited in an autosomal recessive pattern. Digenic, bi-allelic, and polygenic forms have also been reported, in addition to dominant or nonsyndromic forms of genetic mutations. This narrative review reports the causative forms, diagnosis, prognosis, epidemiology, rehabilitation, research, and new treatments of USH.