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Background: LHX3 is a gene encoding a LIM-homeodomain transcription factor important for the fetal development of several organs, such as the pituitary gland, spinal motor neurons and the inner ear. Pathogenic and likely pathogenic variants in the LHX3 gene are infrequent and result in a rare syndrome known as combined pituitary hormone deficiency-3, CPHD3.

Methods: We have studied hearing and vestibular functions in a group of eight individuals, aged 8–36 years, all of whom were homozygous for a specific variant in the LHX3 gene at chromosome 9q34. We reexamined the results of consecutive hearing tests from newborn until April 2024.

Results: Our data showed that all the tested patients had progressive sensorineural hearing deficiency ranging from moderately severe to complete loss. We have performed vestibular testing in six patients and, for the first time, demonstrated that a mutation in the LHX3 gene not only affects hearing, but is also associated with vestibular impairment.

onclusion: The human pathogenic variant c.455-2A > G in the LHX3 gene on chromosome 9q34, which present as a founder mutation in the population in northern Sweden, is responsible for phenotypes associated with progressive hearing loss and balance impairment. These findings prove that the LHX3 gene is crucial for the function of both the cochlear and vestibular organs.