Audiological evaluation in pediatric groups with biotinidase deficiency

Biotinidase is a vital enzyme that facilitates the reuse of biotin, a vitamin, in the body. A deficiency of this enzyme can lead to serious neurological and physical disorders, especially during infancy and childhood. One of the symptoms associated with biotinidase deficiency is hearing loss. The aim of this study is to analyze the frequency of hearing loss in individuals with biotinidase deficiency and to determine whether there is a statistically significant relationship between these two conditions. This study was conducted as a master's thesis by the Audiology Program of the Department of Otorhinolaryngology at Harran University. The study included individuals aged 0-48 months who were diagnosed with biotinidase deficiency at the Pediatric Metabolism Clinic of Harran University Hospital. The target population of the research consists of individuals who applied to Harran University Hospital, while the sample consists of individuals who presented to the Pediatric Metabolism Department of Harran University Hospital with complaints of biotinidase deficiency. In the tests conducted on individuals applying to the Pediatric Metabolism Department, those with a biotin level of "10% or below" are diagnosed with "severe" deficiency, while those with a biotin level of "45% or below" are diagnosed with "partial biotinidase deficiency." After the necessary tests and treatment, the families who agreed to participate in the study were referred to the Audiology unit and included in the research. A total of 90 individuals were included in the study: 50 diagnosed with biotinidase deficiency and 40 individuals without any disabilities or risk factors. After the diagnosis of biotinidase deficiency, participants underwent an otorhinolaryngology examination. Individuals requiring treatment were included after treatment, while those with normal ear examination underwent ABR, OAE, and tympanometry tests. This research is a prospective clinical study aimed at investigating whether biotinidase deficiency has a different effect on children, particularly in relation to hearing loss risk. In the case of significant results, the study aims to include individuals with this diagnosis in routine risk factor categories to ensure early diagnosis and timely treatment. After the participants' guardians were informed about the study, the individuals were included with the guardian's consent. Upon examining the Auditory Brainstem Responses (ABR) of the participants, hearing loss-related findings were observed in 5 individuals (10%) in the biotinidase deficiency group, while all normal individuals had ABR results within normal limits. The difference between the groups was analyzed using Fisher's Exact Test. The p-value obtained from the analysis was approximately 0.06, which is close to the statistical significance threshold. This suggests that there may be subclinical or mild auditory conduction impairment in individuals with biotinidase deficiency. The fact that 10% of individuals with biotinidase deficiency showed signs of hearing loss in the ABR test suggests that the neural transmission pathways or post-cochlear structures may be affected. The absence of such findings in the normal group indicates that this difference could be clinically significant.The results indicate that the rate of hearing loss is higher in individuals with biotinidase deficiency (10% vs. 0%). The p-value, which is near the statistical significance threshold, suggests that significant differences may emerge in studies with larger sample sizes. In the literature, there are studies that establish a relationship between biotinidase deficiency and sensorineural hearing loss. Biotinidase deficiency can affect myelin synthesis and energy metabolism at the cellular level, potentially leading to permanent damage to the cochlea. This, in turn, can result in hearing loss.