NGS sequencing reveals the cause of hearing loss in a group of Polish patients with an isolated, non-DFNB1 hearing loss

The etiology of hearing loss (HL) is heterogeneous. It is estimated that 50-60% of the cases have a genetic background, with the other part being environmental. Isolated HL is responsible for nearly two-thirds of congenital cases, and the remaining part accounts for syndromic forms (SHL). The study aim was to examine the molecular basis of HL in 48 Polish patients with isolated, non-DFNB1 hearing loss using the targeted next-generation sequencing technique (NGS). The molecular cause of the HL was defined in 39.6% (19/48) of patients. In thirteen genes, we identified causative variants, including six novel ones: p.Gly1326Val (STRC), p.Pro104ThrfsTer2 (MYO6), p.Tyr186Ter (GATA3), p.Ile1584SerfsTer12 (MYO15A), p.Pro559Leu, and p.Glu542del (CDH23). The pathogenic status of novel variants was assessed by using bioinformatic tools and the ACMG recommendations. The most frequent genetic variants were the STRC gene deletions and point variants in Usher syndrome genes. For 36.8% of patients, the molecular diagnosis suggested SHL (Deafness-Infertility Syndrome (DIS), Hypoparathyroidism, Sensorineural Deafness and Renal Disease (HDR), Usher, Perrault and Waardenburg syndromes). The obtained results confirmed the heterogeneity of the molecular basis of HL in Polish patients and the usefulness of the NGS technique as a diagnostic tool.