The natural history and genotype-phenotype correlations of TMPRSS3 hearing loss: an international, multi-center, cohort analysis.

TMPRSS3-related hearing loss presents challenges in correlating genotypic variants with clinical phenotypes due to the small sample sizes of previous studies. We conducted a cross-sectional genomics study coupled with retrospective clinical phenotype analysis on 127 individuals. These individuals were from 16 academic medical centers across 6 countries. Key findings revealed 47 unique TMPRSS3 variants with significant differences in hearing thresholds between those with missense variants versus those with loss-of-function genotypes. The hearing loss progression rate for the DFNB8 subtype was 0.3 dB/year. Post-cochlear implantation, an average word recognition score of 76% was observed. Of the 51 individuals with two missense variants, 10 had DFNB10 with profound hearing loss. These 10 all had at least one of 4 TMPRSS3 variants predicted by computational modeling to be damaging to TMPRSS3 structure and function. To our knowledge, this is the largest study of TMPRSS3 genotype-phenotype correlations. We find significant differences in hearing thresholds, hearing loss progression, and age of presentation, by TMPRSS3 genotype and protein domain affected. Most individuals with TMPRSS3 variants perform well on speech recognition tests after cochlear implant, however increased age at implant is associated with worse outcomes. These findings provide insight for genetic counseling and the on-going design of novel therapeutic approaches.

Loss of RBBP4 results in defective inner cell mass, severe apoptosis, hyperacetylated histones and preimplantation lethality in mice†.

Retinoblastoma-binding protein 4 (RBBP4) (also known as chromatin-remodeling factor RBAP48) is an evolutionarily conserved protein that has been involved in various biological processes. Although a variety of functions have been attributed to RBBP4 in vitro, mammalian RBBP4 has not been studied in vivo. Here we report that RBBP4 is essential during early mouse embryo development. Although Rbbp4 mutant embryos exhibit normal morphology at E3.5 blastocyst stage, they cannot be recovered at E7.5 early post-gastrulation stage, suggesting an implantation failure. Outgrowth (OG) assays reveal that mutant blastocysts cannot hatch from the zona or can hatch but then arrest without further development. We find that while there is no change in proliferation or levels of reactive oxygen species, both apoptosis and histone acetylation are significantly increased in mutant blastocysts. Analysis of lineage specification reveals that while the trophoblast is properly specified, both epiblast and primitive endoderm lineages are compromised with severe reductions in cell number and/or specification. In summary, these findings demonstrate the essential role of RBBP4 during early mammalian embryogenesis.

Loss of POLR1D results in embryonic lethality prior to blastocyst formation in mice.

In eukaryotic cells, RNA polymerase (Pol) I and Pol III are dedicated to the synthesis of ribosomal RNA precursors and a variety of small RNAs, respectively. Although RNA Pol I and Pol III complexes are crucial for the regulation of cell growth and cell cycle in all cell types, many of the components of the Pol I and Pol III complexes have not been functionally characterized in mammals. Here, we provide the first in vivo functional characterization of POLR1D, a subunit shared by RNA Pol I and Pol III, during early mammalian embryo development. Our results show that Polr1d mutant embryos cannot be recovered at E7.5 early post-gastrulation stage, suggesting failed implantation. Although Polr1d mutants can be recovered at E3.5, they exhibit delayed/stalled development with morula morphology rather than differentiation into blastocysts. Even with extended time in culture, mutant embryos fail to form blastocysts and eventually die. Analysis of E3.0 embryos revealed severe DNA damage in Polr1d mutants. Additionally, lineage assessment reveals that trophectoderm specification is compromised in the absence of Polr1d. In summary, these findings demonstrate the essential role of POLR1D during early mammalian embryogenesis and highlight cell-lethal phenotype without Polr1d function.

Pediatric sporadic Burkitt lymphoma of the head and neck: A case series and analysis of national trends.

OBJECTIVE: Burkitt lymphoma (BL) is an aggressive form of non-Hodgkin lymphoma with the sporadic subtype being predominant in North America. The clinical presentations and outcomes of pediatric BL within the head and neck were assessed using both an institutional case series and the Surveillance, Epidemiology, and End Results (SEER) Cancer database. METHODS: The electronic medical record at our quaternary children's hospital was queried over a 22-year period (2000-2022) for BL patients with head and neck manifestations. Demographics, clinical presentation, staging, treatment, and outcomes data were collected and analyzed. A corresponding review of the SEER database from 1975 to 2022 was also performed. RESULTS: Our institutional case series identified 48 sporadic BL patients with a mean age of 8.7 years, the majority of whom were male (79 %) and white (74 %). The most common primary sites were the cervical lymph nodes (38 %) and (or) palatine tonsils (23 %). Thirty-five patients (73 %) were treated initially for a presumed inflammatory or infectious process before undergoing malignancy work-up, which did not significantly delay time to diagnosis (31.5 vs. 38.8 days, p = 0.27). The SEER database analysis identified 78 cases, 43.5 % of whom were 5-9 years of age, with a similar male (66 %) and Caucasian (76.9 %) predominance. Cervical lymph nodes were also the most common subsite (67 %), followed by the palatine tonsils (13 %). Remission rates were similar, 93.7 % and 94.8 %, respectively, in both the institutional and SEER database cohorts. CONCLUSION: Unilateral cervical lymphadenopathy and asymmetric tonsillar hypertrophy are the most common presentations in sporadic BL in the head and neck. Clinical presentation in patients with BL is often similar to common, insidious pediatric otolaryngology symptoms and a majority of patients initially undergo treatment for presumed infectious or inflammatory disease. Although overall BL disease-free survival is high even for disseminated BL, the prognosis is better for local/regional disease, and minimizing time to diagnosis and treatment should remain a priority.

Newborn Hearing Screening Results in Patients with Enlarged Vestibular Aqueduct.

OBJECTIVES: Enlarged vestibular aqueduct (EVA) is the most common anatomic abnormality contributing to permanent hearing loss (HL) in children. Although the association between EVA and HL is well-documented, the pass rate for the newborn hearing screening (NBHS) for patients with EVA-related HL is not. Our objective was to investigate the association between NBHS results and audiologic and clinical outcomes in a large cohort of pediatric patients with EVA. METHODS: This was a retrospective chart review of patients seen in the Boston Children's Hospital (BCH) Department of Otolaryngology and Communication Enhancement with confirmed HL, known NBHS results, and confirmed EVA. Demographic, clinical, audiologic, and imaging data were collected from the medical record. Frequency-specific data points from pure-tone audiograms and/or automated auditory brainstem response tests were recorded, and four-frequency pure tone average was calculated using air conduction thresholds at 500, 1000, 2000, and 4000 Hz. RESULTS: Of the 183 patients included in the study, 84 (45.9%) passed their NBHS, whereas 99 (54.1%) did not pass. Compared with patients who did not pass, patients who passed were more likely to have unilateral EVA and unilateral HL, whereas they were less likely to undergo cochlear implantation and to have causative SLC26A4 variants. CONCLUSIONS: EVA-associated HL may be identified at birth or during childhood, with nearly half the patients in this cohort passing their NBHS. Our results provide prognostic information for patients with EVA who pass their NBHS and highlight the importance of regular hearing monitoring for children not initially suspected of having HL. LEVEL OF EVIDENCE: 4 Laryngoscope, 133:2786-2791, 2023.