Biotinidase deficiency and its impact on the auditory system in Iranian children

Biotinidase deficiency (BTD) is a rare autosomal recessive abnormality of biotin metabolism. If left untreated, it may lead to auditory symptoms. In this study, we examined the possible relationship between BTD and hearing impairment among Iranian children.

This descriptive cross-sectional study was performed on 9 children (8 boys, 1 girl) with BTD, who referred to Imam Hossein Hospital in Isfahan City, Iran, in 2018. After collecting their demographic data, including age, gender, weight, height, and history of diseases, we performed routine otolaryngologic and neurologic examination, audiological examinations, including otoscopic, acoustic immittance measurements, and auditory brainstem response (ABR). We recorded cochlear microphonic results in most cases, too.

The subjects’ mean ± SD age of BTD diagnosis was 4.33 ± 5.36 months. Of all participants, 11.1% had a positive family history of the disease, and 66.7% of families had the first-degree consanguineous marriage. About 44.5% of participants had a normal hearing; 22.2% had moderate sensorineural hearing loss, and 33.3% showed no response to ABR test. All subjects showed normal acoustic immittance results. However, children with profound hearing loss showed bilateral absence of acoustic reflexes.

BTD has a high impact on a child’s hearing system. The high prevalence of hearing loss among BTD patients suggests that parents of BTD children (diagnosed at birth) should pay special attention to auditory screening and follow-up programs, as early diagnosis is important for preventing hearing loss. Also, families with first-degree of consanguineous marriages should consider genetic counseling before having children.