Hereditary deafness is clinically and genetically heterogeneous. We investigated deafness segregating as a recessive trait in two families. Audiological examinations revealed an asymmetric mild to profound hearing loss with childhood or adolescent onset. Exome sequencing of probands identified a homozygous c.475G>A;p.(Glu159Lys) variant of CLDN9 (NM_020982.4) in one family and a homozygous c.370_372dupATC;p.(Ile124dup) CLDN9 variant in an affected individual of a second family. Claudin 9 (CLDN9) is an integral membrane protein and constituent of epithelial bicellular tight junctions (TJs) that form semipermeable, paracellular barriers between inner ear perilymphatic and endolymphatic compartments. Computational structural modeling predicts that substitution of a lysine for glutamic acid p.(Glu159Lys) alters one of two cis‐interactions between CLDN9 protomers. The p.(Ile124dup) variant is predicted to locally misfold CLDN9 and mCherry tagged p.(Ile124dup) CLDN9 is not targeted to the HeLa cell membrane. In situ hybridization shows that mouse Cldn9 expression increases from embryonic to postnatal development and persists in adult inner ears coinciding with prominent CLDN9 immunoreactivity in TJs of epithelia outlining the scala media. Together with the Cldn9 deaf mouse and a homozygous frameshift of CLDN9 previously associated with deafness, the two bi‐allelic variants of CLDN9 described here point to CLDN9 as a bona fide human deafness gene.

Breast cancer is one of the main global priorities in terms of public health. It remains the most frequent cancer in women and is the leading cause of their death. The human microbiome plays various roles in maintaining health by ensuring a dynamic balance with the host or in the appearance of various pathologies including breast cancer. In this study, we performed an analysis of bacterial signature differences between tumor and adjacent tissues of breast cancer patients in Morocco. Using 16S rRNA gene sequencing, we observed that adjacent tissue contained a much higher percentage of the Gammaproteobacteria class (35.7%) while tumor tissue was characterized by a higher percentage of Bacilli and Actinobacteria classes, with about 18.8% and 17.2% average abundance, respectively. Analysis of tumor subtype revealed enrichment of genus Sphingomonodas in TNBC while Sphingomonodas was predominant in HER2. The LEfSe and the genus level heatmap analysis revealed a higher abundance of the Rothia genus in tumor tissues. The identified microbial communities can therefore serve as potential biomarkers for prognosis and diagnosis, while also helping to develop new strategies for the treatment of breast cancer patients.

The increasing commercialization of new gene panels based on next-generation sequencing for clinical research has significantly improved our understanding of breast cancer genetics and has led to the discovery of new mutation variants. The study included 16 unselected Moroccan breast cancer patients tested with multi-gene panel (HEVA screen panel) using Illumina Miseq, followed by Sanger sequencing to validate the most relevant mutation. Mutational analysis revealed the presence of 13 mutations (11 single-nucleotide polymorphisms [SNPs] and 2 indels), and 6 of 11 identified SNPs were predicted as pathogenic. One of the 6 pathogenic mutations was c.7874G>C, a heterozygous SNP in HD-OB domain of BRCA2 gene, which led to the arginine to threonine change at codon 2625 of the protein. This work describes the first case of a patient with breast cancer harboring this pathogenic variant and analyzes its functional impact using molecular docking and molecular dynamics simulation. Further experimental investigations are needed to validate its pathogenicity and to verify its association with breast cancer.