Mutations in potassium voltage‐gated channel subfamily Q member 4 (KCNQ4) are etiologically linked to nonsyndromic hearing loss (NSHL), deafness nonsyndromic autosomal dominant 2 (DFNA2). To identify causative mutations of hearing loss in 98 Korean families, we performed whole exome sequencing. In four independent families with NSHL, we identified a cosegregating heterozygous missense mutation, c.140T>C (p.Leu47Pro), in KCNQ4. Individuals with the c.140T>C KCNQ4 mutation shared a haplotype flanking the mutated nucleotide, suggesting that this mutation may have arisen from a common ancestor in Korea. The mutant KCNQ4 protein could reach the plasma membrane and interact with wild‐type (WT) KCNQ4, excluding a trafficking defect; however, it exhibited significantly decreased voltage‐gated potassium channel activity and fast deactivation kinetics compared with WT KCNQ4. In addition, when co‐expressed with WT KCNQ4, mutant KCNQ4 protein exerted a dominant‐negative effect. Interestingly, the channel activity of the p.Leu47Pro KCNQ4 protein was rescued by the KCNQ activators MaxiPost and zinc pyrithione. The c.140T>C (p.Leu47Pro) mutation in KCNQ4 causes progressive NSHL; however, the defective channel activity of the mutant protein can be rescued using channel activators. Hence, in individuals with the c.140T>C mutation, NSHL is potentially treatable, or its progression may be delayed by KCNQ activators.

In Type 1 retinopathy of prematurity in Zone I, intravitreal bevacizumab with concomitant or deferred laser therapy yielded a better anatomical outcome than conventional laser therapy alone. Moreover, intravitreal bevacizumab with deferred laser treatment resulted in less myopic refractive error.