PKHD1L1 and hearing loss disorder: While we have identified individuals in four families with variants in PKHD1L1, this study highlights the necessity for an extended case series with longitudinal audiological follow-up and functional studies to assess variant effects of patient-specific perturbations on development, maturation, and function of the auditory system, as well as explore the potential of accelerated effects of age, noise, or trauma on progression of hearing loss, which remain as current major limitations.