First reported North American calcium binding protein 2-related non-syndromic hearing loss

Pathogenic variants of the calcium binding protein 2 (CABP2) gene have been reported to cause a rare form of autosomal recessive non-syndromic hearing loss, otherwise known as DFNB93. To date, reports of DFNB93 have originated from Europe and Asia. We report the first known case of CABP2-related hearing loss in North America. The patient was diagnosed in infancy with sensorineural hearing loss (SNHL). Genetic panel testing identified the patient as homozygous for CABP2 variant NM_016366.3: c.637+1G>T, consistent with DFNB93. Audiological testing revealed a reverse-slope pattern of hearing loss, differing from the U-shaped pattern associated with previous reports of DFNB93. Hearing aids and multidisciplinary follow-up have led to a positive prognosis. This case highlights the first case of DFNB93 in North America, expands the phenotypical pattern of audiological hearing loss, and emphasises the importance of early detection of congenital SNHL.