Hearing loss is a common feature of symptomatic children with profound biotinidase deficiency.

Sensorineural hearing loss occurs in approximately 75% of symptomatic children with profound biotinidase deficiency, which is more common than originally thought. The hearing loss varies in severity and is usually irreversible. The biochemical, genotype, and clinical variations do not correlate with the development of hearing loss. Thus, it is very important to diagnose the disorder early, especially by newborn screening, to prevent the hearing loss.