Late onset biotinidase deficiency presenting with optic neuropathy and multifocal motor neuropathy phenotype: a case report and literature review
Rattachement africain : Égypte, om. Niveau de preuve : code pays fourni par la source.
Le résumé fourni par la source
Abstract Background Biotinidase deficiency (BTD) is a rare, autosomal recessive neurometabolic disorder that is highly treatable but frequently underdiagnosed, particularly in its late-onset form. It may present with atypical neurological manifestations mimicking inflammatory, hereditary, or neurodegenerative conditions. Case presentation We report a 15-year-old Omani male, born to consanguineous parents, who presented with progressive bilateral painless visual loss over 6 weeks. Neuro-ophthalmological evaluation revealed severe optic neuropathy with absent visual evoked potentials and ganglion cell complex thinning, despite preserved optic disc appearance. Magnetic resonance imaging was unremarkable except for an incidental cervical syrinx. Autoimmune and inflammatory workup, including AQP4 and MOG antibodies, was negative. Whole-exome sequencing identified double homozygous pathogenic variants in the BTD gene, and enzymatic testing confirmed profound biotinidase deficiency. During evaluation, the patient developed subacute distal limb weakness with electrophysiological findings fulfilling diagnostic criteria for multifocal motor neuropathy (MMN), including conduction block with preserved sensory responses. He was treated with high-dose oral biotin and intravenous immunoglobulin (IVIG), resulting in early visual and motor improvement. Conclusion This case highlights late-onset BTD as a diagnostic mimic of Leber hereditary optic neuropathy, neuromyelitis optica spectrum disorder, and MMN. The presence of conduction block neuropathy expands the phenotypic spectrum of BTD. Early recognition is critical, as prompt biotin therapy may lead to neurological improvement. BTD should be considered in unexplained optic neuropathy with multisystem involvement, particularly in consanguineous populations.
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Le contrôle bibliographique ouvert
DOI retrouvé dans Crossref DOI retrouvé ; titre concordant.
- Titre Crossref
- Late onset biotinidase deficiency presenting with optic neuropathy and multifocal motor neuropathy phenotype: a case report and literature review
- Date Crossref
- 17/09/2026
- Éditeur
- Springer Science and Business Media LLC
- Type
- journal-article
Ce recoupement confirme des métadonnées liées au DOI. Il ne confirme ni la méthode ni les conclusions de l’étude, et il ne compte pas comme une seconde source scientifique indépendante.
Où se fait cette recherche
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Cairo University Cairo University, Égypte (code pays fourni par la source)Université ou école supérieure
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University of Nizwa pays non établi dans la noticeUniversité ou école supérieure
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Khoula Hospital Neurology department pays non établi dans la noticeÉtablissement de santé
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Assiut University Assiut University, Égypte (code pays fourni par la source)Université ou école supérieure
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Ministry of Health and Population Égypte (code pays fourni par la source)Organisme public
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Faculty of Medicine Neurology department Cairo University, Égypte (pays nommé en fin d’affiliation)Université ou école supérieure
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Nizwa hospital Neurology unit pays non établi dans la noticeÉtablissement de santé
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Dar Al Salam Hospital Ophthalmology Department Cairo, Égypte (pays nommé en fin d’affiliation)Établissement de santé
Cairo University (Cairo University, Égypte), University of Nizwa et Neurology department — Khoula Hospital, avec 5 autres affiliations. Pays d’affiliation : Égypte.
Une affiliation ne permet pas de déduire la nationalité d’un auteur.