These findings provide new insight in clinical presentation of BB injuries: the identification of unique patterns of symptoms related to BB injuries is useful to perform an early diagnosis (and to guarantee a prompt medical reaction), also when the injury is un-witnessed.

Mutations in the GJB2 gene are responsible for more than half of all cases of recessive non-syndromic deafness. This article presents a mutation analysis of the GJB2, GJB6, OTOF and MTRNR1 genes in 252 patients with sensorineural non-syndromic hearing loss. Thirty-one different mutations were identified in GJB2 and GJB6 in 86 of the 252 (34%) patients. We describe for the first time two new mutations in GJB2: the missense mutation c.29 T>C (p.Leu10Pro) in the N terminal domain and c.326 G>T (p.Gly109Val) in the intracytoplasmic domain of connexin 26. This work shows the high prevalence of GJB2 mutations in the Argentinean population, with frequencies that are comparable to those of the Mediterranean area. Most important, it adds two novel GJB2 mutations to be taken into consideration in the genetic diagnosis of non-syndromic sensorineural hearing loss.

Genetic variants in GJB2 and GJB6 genes are the most frequent causes of hereditary hearing loss among several deaf populations worldwide. Molecular diagnosis enables proper genetic counseling and medical prognosis to patients. In this study, we present an update of testing results in a cohort of Argentinean non-syndromic hearing-impaired individuals. A total of 48 different sequence variants were detected in genomic DNA from patients referred to our laboratory. They were manually curated and classified based on the American College of Medical Genetics and Genomics/Association for Molecular Pathology ACMG/AMP standards and hearing-loss-gene-specific criteria of the ClinGen Hearing Loss Expert Panel. More than 50% of sequence variants were reclassified from their previous categorization in ClinVar. These results provide an accurately interpreted set of variants to be taken into account by clinicians and the scientific community, and hence, aid the precise genetic counseling to patients.

This paper presents a mutation as well as a genotype-phenotype analysis of the GJB2 and GJB6 genes in 476 samples from non-syndromic unrelated Argentinean deaf patients (104 familial and 372 sporadic cases). Most of them were of prelingual onset (82 %) and 27 % were cochlear implanted. Variation of sequences was detected in 171 of the 474 patients (36 %). Overall, 43 different sequence variations were identified in GJB2 and GJB6. Four of them are reported for the first time in GJB2: c.233dupG, p.Ala78Ser, p.Val190Asp and p.Cys211Tyr. Mutations in GJB6 were detected in 3 % of patients [nine del(GJB6-D13S1830) and three del(GJB6-D13S1854)]. Of the 43 different variations identified in GJB2, 6 were polymorphisms and of the others, 10 (27 %) were truncating and 27 (73 %) were nontruncating. Patients with two truncating mutations had significantly worse hearing impairment than all other groups. Moderate phenotypes were observed in a group of patients carrying biallelic mutations (23 %). This work shows the high prevalence of GJB2 mutations in the Argentinean population and presents an analysis of moderate phenotypes in our cohort.

Hearing loss is a heterogeneous disorder. Identification of causative mutations is demanding due to genetic heterogeneity. In this study, we investigated the genetic cause of sensorineural hearing loss in patients with severe/profound deafness. After the exclusion of GJB2-GJB6 mutations, we performed whole exome sequencing in 32 unrelated Argentinean families. Mutations were detected in 16 known deafness genes in 20 patients: ACTG1, ADGRV1 (GPR98), CDH23, COL4A3, COL4A5, DFNA5 (GSDDE), EYA4, LARS2, LOXHD1, MITF, MYO6, MYO7A, TECTA, TMPRSS3, USH2A and WSF1. Notably, 11 variants affecting 9 different non-GJB2 genes resulted novel: c.12829C > T, p.(Arg4277*) in ADGRV1; c.337del, p.(Asp109*) and c.3352del, p.(Gly1118Alafs*7) in CDH23; c.3500G > A, p.(Gly1167Glu) in COL4A3; c.1183C > T, p.(Pro395Ser) and c.1759C > T, p.(Pro587Ser) in COL4A5; c.580 + 2 T > C in EYA4; c.1481dup, p.(Leu495Profs*31) in LARS2; c.1939 T > C, p.(Phe647Leu), in MYO6; c.733C > T, p.(Gln245*) in MYO7A and c.242C > G, p.(Ser81*) in TMPRSS3 genes. To predict the effect of these variants, novel protein modeling and protein stability analysis were employed. These results highlight the value of whole exome sequencing to identify candidate variants, as well as bioinformatic strategies to infer their pathogenicity.