Identification of a novel truncation mutation of EYA4 in moderate degree hearing loss by targeted exome sequencing
The EYA4 gene encodes a 640 amino acid protein that serves as a transcription factor. This protein contains a highly conserved Eya domain (eya HR) and a variable domain (eya VR) Mutations of this gene are known to cause postlingual and progressive sensorineural hearing loss, either as non syndromic (DFNA10) or syndromic hearing loss, depending on the location of truncation of the mutant protein. Since our previous report, we have recruited 14 families segregating autosomal dominant moderate SNHL. A thorough medical history and physical examination including evaluation of heart problems ruled out any syndromic features in these families. Screening of EYA4 was performed by targeted exome sequencing of 134 known deafness genes (TES 134) from the probands. After basic filtering of the variants, we identified one proband who carried a novel truncation mutation, c.1194delT (p.Met401TrpfsX3) of EYA4, making the frequency of DFNA10 to be 7.14 (1/14) in Koreans. The variant co segregated perfectly with a slightly down sloping, moderate degree of SNHL in the family (SH117) and was not detected in any of the 592 normal control chromosomes. This variant is likely to generate protein products that are truncated just downstream of the eya VR domain. None of the three affected family members showed any syndromic features, including cardiac problems, which was compatible with a previous genotype phenotype correlation. The identification of a novel EYA4 truncation mutation associated with DFNA10, rather than syndromic hearing loss, supports a previously reported genotype phenotype correlation in this gene. Considering its detection rate, EYA4 mutations should be suspected in hereditary moderate hearing loss with a corresponding audiologic configuration, and a cardiac examination should be included in the initial evaluation.
European Archives of Oto Rhino Laryngology