Okayasu T, et al. - In Kleefstra syndrome is a rare neurogenetic disorder. This is caused by a subtelomeric 9q34.3 deletion or by an intragenic mutation of the euchromatin histone methyl transferase 1 gene (EHMT1). Hearing loss is reported in nearly 20% to 30% of individuals. Using light microscopy, researchers studied the left temporal bone of one individual with hearing loss. Several abnormalities were detected 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. They identified this work as the first with a published description of the otopathology in Kleefstra syndrome.