Purpose

Biotinidase deficiency (BD) is an autosomal recessively inherited metabolic disorder. Individuals with profound BD develop neurological symptoms. Biotin therapy if initiated early can prevent many of these symptoms. This study comprises the clinical profile and outcome of eight children with profound BD.

Methods

All children with proven profound BD based on assay of serum biotinidase activity using colorimetric method from 2012 to 2018 were included in the study.

Results

The study group comprised of eight children with profound BD with mean (SD) age at onset of symptoms of 8+5.37 months and the mean (SD) age at diagnosis of 22.12+16.47 months. All children presented with refractory seizures, GTCS being the most common semiology. Global developmental delay was present in six children. Dermatitis and alopecia were present in six children. The mean biotinidase level in study group was 0.33 nmol/min/ml. (normal: 29.46 + 9.11). EEG abnormalities were observed in 3 children. The predominant MRI abnormality was delayed myelination. The median (interquartile range) duration of follow-up was 16 (0.5-23.5) months. Cessation of seizures and developmental gains on follow-up were the important outcomes measured. In all children treated with biotin, seizure control was achieved in less than 2 weeks and significant developmental gains were observed on follow-up. Sensorineural hearing loss and pyramidal signs were the predominant residual deficits identified.

Conclusion

BD is a treatable inherited cause of refractory epilepsy in infancy, if unidentified, can lead to sensorineural hearing loss, optic atrophy and developmental delay.