Comprehensive genomic diagnosis of non-syndromic and syndromic hereditary hearing loss in Spanish patients.

BACKGROUND: Sensorineural hearing loss (SNHL) is the most common sensory impairment. Comprehensive next-generation sequencing (NGS) has become the standard for the etiological diagnosis of early-onset SNHL. However, accurate selection of target genomic regions (gene panel/exome/genome), analytical performance and variant interpretation remain relevant difficulties for its clinical implementation. METHODS: We developed a novel NGS panel with 199 genes associated with non-syndromic and/or syndromic SNHL. We evaluated the analytical sensitivity and specificity of the panel on 1624 known single nucleotide variants (SNVs) and indels on a mixture of genomic DNA from 10 previously characterized lymphoblastoid cell lines, and analyzed 50 Spanish patients with presumed hereditary SNHL not caused by GJB2/GJB6, OTOF nor MT-RNR1 mutations. RESULTS: The analytical sensitivity of the test to detect SNVs and indels on the DNA mixture from the cell lines was > 99.5%, with a specificity > 99.9%. The diagnostic yield on the SNHL patients was 42% (21/50): 47.6% (10/21) with autosomal recessive inheritance pattern (BSND, CDH23, MYO15A, STRC [n = 2], USH2A [n = 3], RDX, SLC26A4); 38.1% (8/21) autosomal dominant (ACTG1 [n = 3; 2 de novo], CHD7, GATA3 [de novo], MITF, P2RX2, SOX10), and 14.3% (3/21) X-linked (COL4A5 [de novo], POU3F4, PRPS1). 46.9% of causative variants (15/32) were not in the databases. 28.6% of genetically diagnosed cases (6/21) had previously undetected syndromes (Barakat, Usher type 2A [n = 3] and Waardenburg [n = 2]). 19% of genetic diagnoses (4/21) were attributable to large deletions/duplications (STRC deletion [n = 2]; partial CDH23 duplication; RDX exon 2 deletion). CONCLUSIONS: In the era of precision medicine, obtaining an etiologic diagnosis of SNHL is imperative. Here, we contribute to show that, with the right methodology, NGS can be transferred to the clinical practice, boosting the yield of SNHL genetic diagnosis to 50-60% (including GJB2/GJB6 alterations), improving diagnostic/prognostic accuracy, refining genetic and reproductive counseling and revealing clinically relevant undiagnosed syndromes.

Manifestaciones audiovestibulares en la malformación de Chiari tipo I. Serie de casos y revisión bibliográfica / Audio-vestibular signs and symptoms in Chiari malformation type I. Case series and literature review

Introducción: La malformación de Chiari es una alteración de la base del cráneo, en la que se produce herniación del cerebelo y del tronco cerebral a través del foramen magnum. Aunque su forma de presentación más frecuente es la cefalea occipitonucal, no es rara la asociación de síntomas audiovestibulares. El objetivo de nuestro estudio fue conocer las manifestaciones audiovestibulares en la malformación de Chiari tipo i (MCH-I). Material y métodos: Se realizó un estudio retrospectivo observacional de los pacientes remitidos a nuestra unidad en los últimos 5 años, así como una revisión bibliográfica de las manifestaciones audiovestibulares de esta enfermedad. Resultados: Se presentan 9 pacientes (2 varones y 7 mujeres) de 42,8 años de edad media. Cinco de los pacientes consultaron con un síndrome menieriforme, 2 casos como vértigo recurrente de características periféricas, otro como hipoacusia súbita y el último caso como hipoacusia neurosensorial de inicio en la infancia. La manifestación audiovestibular más frecuentemente descrita en la literatura en pacientes es la inestabilidad (49%), seguida de vértigo (18%), nistagmo (15%) e hipoacusia (15%). Dentro del nistagmo, el más frecuente es el nistagmo horizontal (74%) seguido del vertical hacia abajo (18%). Otras manifestaciones audiovestibulares son acúfenos (11%), plenitud ótica (10%) e hiperacusia (1%). La cefalea occipitonucal que aumenta con las maniobras de Valsalva y las parestesias en las manos son muy sugestivos de esta enfermedad. Conclusiones: La aparición de síntomas audiovestibulares en la MCH-I hace que sea relativamente frecuente su derivación al otoneurólogo. Estos pacientes presentan inestabilidad, síndrome vertiginoso e hipoacusia neurosensorial. No es rara la presencia de nistagmo, sobre todo horizonal y vertical hacia abajo. Es importante la familiarización de los otoneurólogos con la sintomatología de esta enfermedad de cara a su diagnóstico diferencial (AU)

Introduction: Chiari malformation is an alteration of the base of the skull with herniation through the foramen magnum of the brain stem and cerebellum. Although the most common presentation is occipital headache, the association of audio-vestibular symptoms is not rare. The aim of our study was to describe audio-vestibular signs and symptoms in Chiari malformation type i (CM-I). Materials and methods: We performed a retrospective observational study of patients referred to our unit during the last 5 years. We also carried out a literature review of audio-vestibular signs and symptoms in this disease. Results: There were 9 patients (2 males and 7 females), with an average age of 42.8 years. Five patients presented a Ménière-like syndrome; 2 cases, a recurrent vertigo with peripheral features; one patient showed a sudden hearing loss; and one case suffered a sensorineural hearing loss with early childhood onset. The most common audio-vestibular symptom indicated in the literature in patients with CM-I is unsteadiness (49%), followed by dizziness (18%), nystagmus (15%) and hearing loss (15%). Nystagmus is frequently horizontal (74%) or down-beating (18%). Other audio-vestibular signs and symptoms are tinnitus (11%), aural fullness (10%) and hyperacusis (1%). Occipital headache that increases with Valsalva manoeuvres and hand paresthesias are very suggestive symptoms. Conclusions: The appearance of audio-vestibular manifestations in CM-I makes it common to refer these patients to neurotologists. Unsteadiness, vertiginous syndromes and sensorineural hearing loss are frequent. Nystagmus, especially horizontal and down-beating, is not rare. It is important for neurotologists to familiarise themselves with CM-I symptoms to be able to consider it in differential diagnosis (AU)

Audio-vestibular signs and symptoms in Chiari malformation type i. Case series and literature review.

INTRODUCTION: Chiari malformation is an alteration of the base of the skull with herniation through the foramen magnum of the brain stem and cerebellum. Although the most common presentation is occipital headache, the association of audio-vestibular symptoms is not rare. The aim of our study was to describe audio-vestibular signs and symptoms in Chiari malformation type i (CM-I). MATERIALS AND METHODS: We performed a retrospective observational study of patients referred to our unit during the last 5 years. We also carried out a literature review of audio-vestibular signs and symptoms in this disease. RESULTS: There were 9 patients (2 males and 7 females), with an average age of 42.8 years. Five patients presented a Ménière-like syndrome; 2 cases, a recurrent vertigo with peripheral features; one patient showed a sudden hearing loss; and one case suffered a sensorineural hearing loss with early childhood onset. The most common audio-vestibular symptom indicated in the literature in patients with CM-I is unsteadiness (49%), followed by dizziness (18%), nystagmus (15%) and hearing loss (15%). Nystagmus is frequently horizontal (74%) or down-beating (18%). Other audio-vestibular signs and symptoms are tinnitus (11%), aural fullness (10%) and hyperacusis (1%). Occipital headache that increases with Valsalva manoeuvres and hand paresthesias are very suggestive symptoms. CONCLUSIONS: The appearance of audio-vestibular manifestations in CM-I makes it common to refer these patients to neurotologists. Unsteadiness, vertiginous syndromes and sensorineural hearing loss are frequent. Nystagmus, especially horizontal and down-beating, is not rare. It is important for neurotologists to familiarise themselves with CM-I symptoms to be able to consider it in differential diagnosis.