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Objective Hearing loss (HL) is the most common sensory-neural defect and the most heterogeneous trait in humans, with the involvement of >100 genes, which make a molecular diagnosis problematic. Next-generation sequencing (NGS) is a new strategy that can overcome this problem. Study Design Descriptive experimental study. Setting Diagnostic laboratory. Subjects and Methods A comprehensive family history was obtained, and clinical evaluations and pedigree analysis were performed in a family with multiple individuals with HL. As the first tier, GJB2 was sequenced, and genetic linkage analysis of DFNB1A/B was performed to rule out the most common cause of the disease. Targeted NGS was used to unravel the molecular etiology of the disease in the HL-associated genes in the proband. Two homozygous variants remained in OTOF after proper filtration. Cosegregation and in silico analysis were done. Preimplantation genetic diagnosis (PGD) was accomplished via linkage analysis and direct sequencing of the pathogenic variant. Results Clinical evaluations suggested autosomal recessive nonsyndromic HL. Two homozygous variants, c.367G>A (p.Gly123Ser) and c.1392+1G>A, were identified in cis status. c.1392+1G>A met the criteria for being pathogenic according to the variant interpretation guideline of the American College of Medical Genetics and Genomics. PGD was successfully performed to prevent the recurrence of the disease in the related family. Conclusion A novel OTOF mutation causing HL was identified. Here, we report the effectiveness of the combined application of targeted NGS and PGD in diagnosis and prevention of hereditary HL.

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NGS is very promising to identify the molecular etiology of highly heterogeneous diseases such as HL. MARVELD2 might be important in the etiology of HL in this region of Iran.

Hearing loss is caused both by genetic and environmental factors. In this sense, more than half of the cases are genetic. Hereditary hearing loss is divided into syndromic and nonsyndromic cases. Main pattern of inheritance (80%) in non-syndromic cases is autosomal recessive, which is known as autosomal recessive non-syndromic hearing loss (ARNSHL). Although the disease is very genetically heterogeneous, the GJB2 gene has 838