Otopathology in Kleefstra Syndrome: A Case Report.

Kleefstra syndrome is a rare neurogenetic disorder caused by a subtelomeric 9q34.3 deletion or by an intragenic mutation of the euchromatin histone methyl transferase 1 gene (EHMT1). Approximately 20% to 30% of individuals have hearing loss. The left temporal bone of one subject with hearing loss was studied using light microscopy. There were several abnormalities including dysostosis of the stapes without fixation, enlarged vestibular aqueduct, anomalies of the organ of Corti in the basal turn, cyst formation in the stria vascularis, and dysmorphia of the cochlear modiolus and the vestibular labyrinth. This is the first published description of the otopathology in Kleefstra syndrome. Laryngoscope, 130:2028-2033, 2020.