REVIEW | doi:10.20944/preprints202007.0583.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: genetic association studies; extreme phenotype; genetic epidemiology; tinnitus
Online: 24 July 2020 (13:43:00 CEST)
Exome sequencing has been commonly used in rare diseases by selecting multiplex families or singletons with an extreme phenotype (EP) to search for rare variants in coding regions. The EP strategy covers both extreme ends of a disease spectrum and it has been also used to investigate the contribution of rare variants to heritability in complex clinical traits. We have conducted a systematic review to find evidence supporting the use of EP strategies to search for rare variants in genetic studies of complex diseases, to highlight the contribution of rare variation to the genetic structure of multiallelic conditions. After performing the quality assessment of the retrieved records, we selected 19 genetic studies considering EP to demonstrate genetic association. All the studies successfully identified several rare variants, de novo mutations and many novel candidate genes were also identified by selecting an EP. There is enough evidence to support that the EP approach in patients with an early onset of the disease can contribute to the identification of rare variants in candidate genes or pathways involved in complex diseases. EP patients may contribute to a better understanding of the underlying genetic architecture of common heterogeneous disorders such as tinnitus or age-related hearing loss.
REVIEW | doi:10.20944/preprints202302.0321.v1
Subject: Biology And Life Sciences, Cell And Developmental Biology Keywords: human induced pluripotent stem cells; inner ear disorders; disease modeling; sensorineural hearing loss; Meniere disease; biomedical applications
Online: 20 February 2023 (06:17:44 CET)
Genetic sensorineural hearing loss and Meniere disease have been associated with rare variations in the coding and non-coding region of the human genome. Most of these variants are classified as likely pathogenic or variants of unknown significance and require functional validation in cellular or animal models. Given the difficulties to obtain human samples and the raising concerns about animal experimentation, human induced pluripotent stem cells emerge as cellular models to investigate the interaction of genetic and environmental factors in the pathogenesis of inner ear disorders. The generation of human sensory epithelia and neuron-like cells carrying the variants of interest may facilitate a better understanding of their role during differentiation. These cellular models will allow us to explore new strategies for restoring hearing and vestibular sensory epithelia as well as neurons. This review summarizes the use of human induced pluripotent stem cells in sensorineural hearing loss and Meniere disease and proposes some strategies for its application in clinical practice.
ARTICLE | doi:10.20944/preprints202110.0030.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: Meniere Disease; cytokines; WGBS; Hearing Loss; DNA methylation
Online: 1 October 2021 (16:03:48 CEST)
Meniere Disease (MD) is a multifactorial disorder of the inner ear characterized by vertigo attacks associated with sensorineural hearing loss and tinnitus with a significant heritability. Although MD has been associated with several genes, no epigenetic studies have been performed in MD. Here we performed whole genome bisulfite sequencing in 14 MD patients and 6 healthy controls, with the aim of identifying a MD methylation signature and potential disease mechanisms. We observed a high number of differentially methylated CpGs (DMC) when comparing MD patients to controls (N= 9,545), several of them in hearing loss genes such as PCDH15, ADGRV1 and CDH23. Bioinformatic analyses of DMCs and cis-regulatory regions predicted phenotypes related to abnormal excitatory postsynaptic currents, abnormal NMDA-mediated receptor currents and abnormal glutamate-mediated receptor currents when comparing MD to controls. Moreover, we identified various DMCs in genes previously associated with cochleovestibular phenotypes in mice. We have also found 12 undermethylated regions (UMR) that were exclusive to MD, including 2 UMR in an inter CpG island in the PHB gene. We suggest that the DNA methylation signature allows to distinguish between MD patients and controls. The enrichment analysis confirms previous findings of a chronic inflammatory process underlying MD.