Next-Generation Sequencing Identifies Pathogenic Variants in HGF, POU3F4, TECTA, and MYO7A in Consanguineous Pakistani Deaf Families

Investigating POU3F4 in cancer: Expression patterns, prognostic implications, and functional roles in tumor immunity

Research has demonstrated that POU3F4 is integral to various cancers, in addition to its significance in inner ear development, pancreatic differentiation, as well as neural stem cell differentiation. Nevertheless, comprehensive pan-cancer analyses focusing on POU3F4 remain limited. This study aims to assess the prognostic value of POU3F4 in thirty-three cancers and explore its immune-related functions. Based on data from The Cancer Genome Atlas (TCGA), Cancer Cell Line Encyclopedia (CCLE), Genotype-Tissue Expression (GTE), and Gene Set Cancer Analysis (GSCA), we employed various bioinformatics approaches to investigate the potential carcinogenic effects of POU3F4. Our study encompassed DNA methylation, RNA methylation, tumor mutation burden (TMB), mismatch repair (MMR) genes, microsatellite instability (MSI), the relationship between POU3F4 and prognosis, and immune cell infiltration (ICI) across different tumors. The analysis revealed that POU3F4 expression is typically low in most cancers but is elevated in breast invasive carcinoma, glioblastoma multiforme (GBM), liver hepatocellular carcinoma, and thyroid carcinoma, with the highest levels in GBM. Additionally, POU3F4 expression correlates with cancer prognosis, either positively or negatively. The expression of POU3F4 demonstrated significant associations with MSI in four cancers and TMB in six cancers. POU3F4 expression was significantly linked to DNA methylation in 13 cancer types and RNA methylation in most cancers. It also correlated with the tumor immune microenvironment, immune-related genes, immune checkpoint inhibitors, and drug resistance in various cancers. In vitro experiments demonstrated that POU3F4 enhances cell viability, proliferation, and migration in GBM. Our findings indicate that, given its critical role in carcinogenesis and tumor immunity, POU3F4 serves as a prognostic marker in diverse malignancies.

Syndromic Hearing Loss in Children

Pattern recognition of specific temporal bone radiological phenotypes, in association with abnormalities in other organ systems, is critical in the diagnosis and management of syndromic causes of hearing loss. Several recent publications have demonstrated the presence of specific radiological appearances, allowing precise genetic and/or syndromic diagnosis, in the right clinical context. This review article aims to provide an extensive but practical guide to the radiologist dealing with syndromic causes of hearing loss.

Clinical and Molecular Aspects Associated with Defects in the Transcription Factor POU3F4: A Review

X-linked deafness (DFNX) is estimated to account for up to 2% of cases of hereditary hearing loss and occurs in both syndromic and non-syndromic forms. POU3F4 is the gene most commonly associated with X-linked deafness (DFNX2, DFN3) and accounts for about 50% of the cases of X-linked non-syndromic hearing loss. This gene codes for a transcription factor of the POU family that plays a major role in the development of the middle and inner ear. The clinical features of POU3F4-related hearing loss include a pathognomonic malformation of the inner ear defined as incomplete partition of the cochlea type 3 (IP-III). Often, a perilymphatic gusher is observed upon stapedectomy during surgery, possibly as a consequence of an incomplete separation of the cochlea from the internal auditory canal. Here we present an overview of the pathogenic gene variants of POU3F4 reported in the literature and discuss the associated clinical features, including hearing loss combined with additional phenotypes such as cognitive and motor developmental delays. Research on the transcriptional targets of POU3F4 in the ear and brain is in its early stages and is expected to greatly advance our understanding of the pathophysiology of POU3F4-linked hearing loss.

Considering gene therapy to protect from X-linked deafness DFNX2 and associated neurodevelopmental disorders

Mutations and deletions in the gene or upstream of the gene encoding the POU3F4 transcription factor cause X-linked progressive deafness DFNX2 and additional neurodevelopmental disorders in humans. Hearing loss can be purely sensorineural or mixed, that is, with both conductive and sensorineural components. Affected males show anatomical abnormalities of the inner ear, which are jointly defined as incomplete partition type III. Current approaches to improve hearing and speech skills of DFNX2 patients do not seem to be fully effective. Owing to inner ear malformations, cochlear implantation is surgically difficult and may predispose towards severe complications. Even in cases where implantation is safely performed, hearing and speech outcomes remain highly variable among patients. Mouse models for DFNX2 deafness revealed that sensorineural loss could arise from a dysfunction of spiral ligament fibrocytes in the lateral wall of the cochlea, which leads to reduced endocochlear potential. Highly positive endocochlear potential is critical for sensory hair cell mechanotransduction and hearing. In this context, here, we propose to develop a therapeutic approach in male Pou3f4 -/y mice based on an adeno-associated viral (AAV) vector-mediated gene transfer in cochlear spiral ligament fibrocytes. Among a broad range of AAV vectors, AAV7 was found to show a strong tropism for the spiral ligament. Thus, we suggest that an AAV7-mediated delivery of Pou3f4 complementary DNA in the spiral ligament of Pou3f4 -/y mice could represent an attractive strategy to prevent fibrocyte degeneration and to restore normal cochlear functions and properties, including a positive endocochlear potential, before hearing loss progresses to profound deafness.

Molecular genetic landscape of hereditary hearing loss in Pakistan

Approximately 14.5 million Pakistani individuals have a hearing loss and half of these cases may be due to genetic causes. Though significant progress has been made in uncovering genetic variants for recessively inherited nonsyndromic deafness, Pendred syndrome, and Usher syndromes, the same is not true for dominantly inherited hearing loss, most syndromic cases and deafness with complex inheritance patterns. Variants of 57 genes have been reported to cause nonsyndromic recessive deafness in Pakistan, though most are rare. Variants of just five genes GJB2, HGF, MYO7A, SLC26A4, and TMC1 together explain 57% of profound deafness while those of GJB2, MYO15A, OTOF, SLC26A4, TMC1, and TMPRSS3 account for 47% of moderate to severe hearing loss. In contrast, although variants of at least 39 genes have been implicated in different deafness syndromes, their prevalence in the population and the spectrum of mutations have not been explored. Furthermore, research on genetics of deafness has mostly focused on individuals from the Punjab province and needs to be extended to other regions of Pakistan. Identifying the genes and their variants causing deafness in all ethnic groups is important as it will pinpoint rare as well as recurrent mutations. This information may ultimately help in offering genetic counseling and future treatments.