Biotinidase Deficiency Induced Optic Neuropathy: A Case Report and Literature Review.

We report a case of a 19-year-old Somali American woman who presented with 6 months of progressive bilateral vision changes and ocular discharge, with systemic symptoms including angular cheilitis and dermatitis. The patient was evaluated with comprehensive ophthalmic examination, optical coherence tomography, corticospinal magnetic resonance imaging, and fundus imaging. Comprehensive ophthalmic examination revealed bilateral optic neuropathy. Laboratory testing showed a biotinidase level of <0.1 (normal, 5.5-10 nmol/min/ml). The patient was treated with oral biotin supplementation with improvement in her visual function. Furthermore, a review of the literature of reported cases of biotinidase deficiency optic neuropathy published between June 1987 and February 2024 revealed 40 cases. This entity presents more commonly in males (63%) (n = 27), with an average age of 11.7 ± 12.0 years (n = 35). Patients experienced symptoms for an average of 4.3 ± 8.3 years before they were correctly diagnosed (n = 25). Individuals had an average BCVA of 20/300 in the right eye and 20/250 in the left eye (n = 15) at the time of presentation. Additionally, 38.9% of patients had color vision deficits (n = 18), and 100% of patients had visual field deficits (n = 19). All patients were treated with oral biotin supplementation (n = 25). This case and review of the literature underscore that biotinidase deficiency should be considered in patients with bilateral and progressive optic neuropathy among young adults. Early diagnosis is important as biotin supplementation may halt and/or reverse the disease process.