Auditory function at birth in infants with biotinidase deficiency

Biotinidase deficiency (BD) is a metabolic disorder associated with acquired sensorineural hearing loss when diagnosis and treatment are delayed. However, although it is known to be a cause of acquired sensorineural hearing loss, studies evaluating auditory function in the neonatal period are insufficient. This study aimed to evaluate newborn hearing screening outcomes in neonates diagnosed with BD and to investigate the relationship between biotinidase enzyme activity levels and auditory brainstem response (ABR) results.

This retrospective study included neonates diagnosed with BD between May 2023 and April 2024 in a tertiary hospital. Neonates without risk factors and with available ABR results were included. A control group of healthy neonates with matched birth dates was randomly selected. Newborn hearing screening was performed using automated ABR within the first two weeks of life. Neonates were categorized according to biotinidase enzyme activity as severe (<10%), partial (10-30%), or normal (>30%). ABR outcomes and demographic variables were compared between groups.

Newborn hearing screening outcomes did not differ significantly between neonates with BD and controls (p = 0.688). Within the BD group, ABR pass and refer rates were similar across enzyme activity subgroups (p = 0.949). No correlation was observed between biotinidase enzyme activity levels and ABR results in the neonatal period (p = 0.099).

Neonates with biotinidase deficiency demonstrate normal newborn hearing screening results comparable to healthy controls. These findings suggest that hearing loss in BD is not congenital but develops later if untreated. Long-term audiological follow-up remains essential despite normal neonatal screening results.