Anomalies of the auditory nerve in hereditary syndromes

Anomalies of the auditory nerve (AN) is a significant obstacle to the auditory and speech rehabilitation of the child. Hypoplasia/aplasia of the AN can cause both isolated hearing loss and be detected as part of hereditary syndromes. Objective: to assess the proportion of hereditary etiology in a group of children with hypo-/aplasia of the AN. Genetic counseling was carried out for 16 children with bilateral hypo-/aplasia of the AN, who underwent cochlear implantation (CI). Isolated forms of bilateral hypo-/aplasia of the AN were established in 6 children, 10 children have signs of syndromes, including CHARGE syndrome in 4 children, X-linked stapes fixation syndrome – 1, Noonan syndrome – 1, and 4 children with undifferentiated syndromic forms. Whole exome sequencing revealed pathogenic variants of the CHD7 gene in 3 children and confirmed CHARGE syndrome, one child had variant of unknown significance in the EFTUD2 gene (mandibular-facial dysostosis with microcephaly), another had a pathogenic variant in the POU3F4 gene, and the third had a variant of unknown significance in the GNAO1 gene (neurodevelopmental disorder with involuntary movements). No pathogenic or likely pathogenic variants were detected in 6 children with isolated hypo-/aplasia of the AN. In all cases, the detected variants were consistent with the clinical picture. No pathogenic or likely pathogenic variants were detected in the remaining patients, including 6 children with isolated hypo-/aplasia of АN. Genetic heterogeneity in hypoplasia/aplasia of AN is shown. Half of the children in the examined group had syndromic forms of hearing loss, which allows early detection of such children. According to our results, patients with CI received a significant advantage that allowed them to develop and optimally use new social communication skills.

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